Twyman-Green interferometer adjustment device

The device includes a measuring surface area of a Twyman interferometer which forms the first surface area of an optical system arranged in the beam direction. The optical system contains an adjustment system, which represents an interferometer, whereby the centres of curvature of the measuring surface area and the surface areas of the adjustment system are aligned with each other. The adjustment of the Twyman interferometer is correctly achieved, if the structure of the interferogram which results from the adjustment system is optimized with respect to any other adjustment. For example, the adjustment is correct if the system minimises intensity modulation or reaches an extreme of an evaluation function after a mathematical transformation.

Verfahren zur Kalibrierung eines Messgerätes

Verfahren zur Kalibrierung eines Messgeräts (10) mit den Schritten: Mit endlicher Genauigkeit und damit Positionierfehler-behaftet erfolgendes Anfahren von verschiedenen, in einem Prüfvolumen (24) des Messgerätes liegenden und durch Orts- und/oder Winkelkoordinaten auszeichnungsbaren Messpositionen, Erzeugen von Messsignalen in den jeweiligen Punkten und Bestimmen von Parametern eines Rechenmodells des Messgeräts aus den Messsignalen und den Orts- und/oder Winkelkoordinaten, dadurch gekennzeichnet, dass ein Koordinatensystem, auf welches sich die Koordinaten der Punkte des Prüfvolumens beziehen, aus fehlerbehaftet angefahrenen Messpositionen definiert wird, indem exakt sechs Koordinaten von mindestens drei Messpositionen vorbestimmte Koordinatenwerte zugewiesen werden.

Positionsmeßeinrichtung

The invention relates to a position measuring device which is used for determining the position of two mobile parts relatively to each other in a measurement direction. Said device allows for creating an absolute reference during measurement. For this purpose, it comprises a light source and a beam splitting member which splits the radiation beam from the light source in at least one first and one second partial radiation beam. Said beams are then oriented preferably parallel to each other at the outlet of the beam splitting member. In addition, the invention provides for a reference reflector and a measuring reflector which are impacted by the two partial beams. A reference mark and a scanning unit are provided on the measuring reflector for producing a reference pulsed signal at the location of the stationary reference reflector.

Apparatus for precise length measurement calibration

MEASUREMENT OF COMPLEX SURFACE FORMS USING A SPHERICAL WAVE FRONT

INTERFEROMETER

SYSTEM TO OPTICAL COHERENCY TOMOGRAPHY

INTERFEROMETER

INTERFEROMETER OPTICAL ELEMENT ALIGNMENT

AN ARTIFACT FOR IMPROVING VERTICAL RESOLUTION OF RADIATION-BASED IMAGING

An artifact (100) for improving the vertical resolution of radiation-based imaging is presented. The artifact has a stepped thickness profile with steps (106-110). Adjacent steps are arranged to interact differently with radiation used in the radiation-based imaging. Thus, it is possible to identify which step is, in each imaging situation, vertically closest to the imaging plane related to the radiation-based imaging. Thus, a pre-determined vertical position-value related to the closest one of the steps can be used as a vertical position-value related to a radiation-based imaging result obtained in the imaging situation.

INTERFEROMETRY TESTING OF LENSES, AND SYSTEMS AND DEVICES FOR SAME

Modified MZ (Mach-Zender) interferometers preferably are utilized to analyze the transmitted, aspherical wavefront of an ophthalmic lens by mounting the lens in a cuvette having a rotatable carousel that can hold multiple lenses. Fresh, temperature controlled, saline solution is circulated about the lenses, and the cuvette is positioned in a vertical test arm of the interferometer configuration. Reverse raytracing preferably is utilized to remove aberrations induced into the wavefront as it is imaged from immediately behind the lens to the detector of the interferometer.

INTERFEROMETRY

An interferometer utilises a short coherence length light source in such a way that the visibility of fringes produced varies as a function of the measurand. In order to provide a signal which represents the value of the measurand, the visibility of the fringes is calculated.

DEVICE OF OPTICAL MEASUREMENT Of a PHYSICAL PARAMETER

METHOD AND DEVICE FOR INSPECTING A SURFACE OF AN OBJECT HAVING DISSIMILAR MATERIALS

양측면 측정 성능을 갖는 스침-입사 간섭계

... 스침-입사 간섭계는 사이에 통상의 평면 대상이 있는 공간 이격된 제1 및 제2회절 광학소자를 포함한다. 제1회절 광학 소자는 스침-입사각으로 대상의 대향하는 제1 및 제2표면으로부터 반사되는 전단된 1차 회절 광 빔을 형성하고, 반면 0차 회절 광 빔은 반사되지 않는다. 제2회절 광학소자는 시준된 결합 광 빔을 형성하기 위해 비반사의 0차 회절 광 빔과 전단된 반사 광 빔을 결합한다. 1X 더블-텔레센트릭 릴레이 시스템은 이미지 평면에 위치된 확산 스크린 상에 제1 및 제2간섭 이미지를 형성하는 폴딩 광학 시스템에 결합된 광 빔을 릴레이한다. 제1 및 제2간섭 이미지의 디지털 이미지가 얻어지고 대상의 두께 변화를 특징화하도록 처리된다.

Device for measuring a substrate and method for correcting cyclic error components of an interferometer

The invention relates to a device (1) for measuring a substrate (3) for semiconductor lithography with a reference interferometer (20) for ascertaining the change in the ambient conditions, wherein the reference interferometer (20) comprises a means (18, 27) for changing the optical path length of a measurement section of the reference interferometer (20), wherein the means (18, 27) is configured to bring about a change in the refractive index. Furthermore, the invention relates to a method (1) for correcting cyclic error components of a reference interferometer (20), wherein the reference interferometer (20) comprises a means (18, 27) for changing the optical path length of a measurement section of the reference interferometer (20), comprising the following method steps: - starting up the reference interferometer (20), - continuously detecting measurement values of the reference interferometer (20), - changing the optical path length of the measurement section of the reference interferometer ...

APPARATUS AND METHOD FOR MEASURING CHARACTERISTICS OF SURFACE FEATURES

An apparatus is disclosed which includes an interferometry system configured to operate in a first mode to produce a first set of multiple interferometry signals corresponding to different illumination angles of a test object by test light and in a second mode produce a second set of multiple interferometry signals corresponding to different surface locations of a test object. An electronic processor coupled to the interferometry system is configured to receive the first set of interferometry signals and programmed to compare information derivable from the first set of multiple interferometry signals to information corresponding to multiple models of the test object to determine information related to one or features of the test object, and output the information. In some embodiments, the features include an under-resolved feature.

METHOD OF MEASURING A SHAPE OF AN OPTICAL SURFACE AND INTERFEROMETRIC MEASURING DEVICE

A method of measuring a shape of an optical surface (14) of a test object (12) is provided. The method comprises the steps of: providing an interferometric measuring device (16) generating a measurement wave (18), arranging the interferometric measuring device (16) and the test object (12) consecutively at different measurement positions relative to each other, such that different regions (20) of the optical surface (14) are illuminated by the measurement wave (18), measuring the positional coordinates of the measuring device (16) at the different measurement positions in relation to the test object (12), obtaining surface region measurements by interferometrically measuring the wavefront of the measurement wave (18) after interaction with the respective region (20) of the optica! surface (14) using the measuring device (16) in each of the measurement positions, and determining the actual shape of the optical surface (14) by computationally combining the sub-surface measurements based on ...

LATERAL DISTORTION CORRECTED OPTICAL COHERENCE TOMOGRAPHY SYSTEM

A lateral-distortion corrected optical coherence tomography system. The system can include an optical coherence tomography sensor, a light source, a fiber-optic system arranged to provide a reference beam and an observation beam, an optical detection system arranged to receive combined light from the reference beam and the observation beam and to provide detection signals, and a data processing system arranged to communicate with the optical detection system and receive the detection signals. The data processing system can be configured to assemble an image corresponding to a scanning path by constructing a plurality of A-scans from the detection signals, determining displacement information from the plurality of A-scans, and arranging the plurality of A-scans according to the displacement information.

Method for image calibration and apparatus for image acquiring

The present invention relates to a method for image calibration and an apparatus for image acquiring. In the method for image calibration, the image formation position for an image acquiring unit of the apparatus is calibrated according to the relative location of the image acquiring unit to a objective lens of the apparatus, wherein the relative location is determined by calculating the focus index of the image acquired by the image acquiring unit so that a clear and sharp interferogram can be obtained for three dimensional surface profile measuring. In addition, it is possible to obtain a clear and sharp image without any interference fringe outside the coherent range by adjusting the image formation position, which is capable of being utilized for two dimensional defect detection and dimension measurement.

Integrated interference scanning method

An integrated interference scanning method, mainly used to integrate the respective advantages of VSI and PSI measurements, hereby achieving the characteristic of high precision and limitless measurement range. In particular, the slope correction factor and the displacement correction factor between the VSI measurement and PSI measurement may be utilized to execute the integration calculation of the height data arrays of the VSI and PSI, so that the scanning procedure may be achieved through merely using the wideband light source of the interference scanning system, as such reducing the errors and complexity of the interference scanning system.

System for optical coherence tomography

System and method for optical coherence tomography

Die Erfindung betrifft ein System sowie ein entsprechendes Verfahren zur optischen Kohärenztomographie mit einem Interferometer (10, 20) zur Ausgabe von Licht, mit dem eine Probe (1) bestrahlt wird, wobei das Interferometer (10, 20) einen Strahlteiler (13, 24) und mindestens einen Reflektor (11, 12, 25) umfasst, und einem Detektor (30) mit einer ersten Anzahl von in einer ersten Fläche angeordneten Detektorelementen zur Erfassung von Licht, welches von der Probe (1) reflektiert wird. Um auf einfachere und schnellere Weise, insbesondere in Echtzeit, Bilder einer Probe (1) aufnehmen zu können, ist das System in einem ersten Modus, insbesondere einem ersten Echtzeitmodus, betreibbar, in welchem von der Probe (1) reflektiertes Licht nur von einer zweiten Anzahl von Detektorelementen des Detektors (30) erfasst und in entsprechende Detektorsignale umgewandelt wird, wobei die zweite Anzahl der Detektorelemente kleiner ist als die erste Anzahl der Detektorelemente. Darüber hinaus ist das System ...

MEASURING METHOD

System und Verfahren zur optischen Kohärenztomographie

Optisches Interferometer zur Messung von Dickenänderungen

Interferometric method for measuring spaces uses an interferometer to separate a source beam for a source of light emitting short-coherent or incoherent light into reference and measuring beams

Reference and measured beams of light split into two sub-beams. One reference and one measured sub-beam trace a first beam path (FBP) (12) to be reflected on a stepped body (SB) (16). Optical distance in the FBP depends on point of reflection on the SB. Second reference and measured sub-beams trace a second beam path (11) in a second interferometer. All sub-beams are fed to a detector (15). An independent claim is also included for a device for interferometric measurement.

Computer-generiertes Hologramm (CGH), sowie Verfahren zur Charakterisierung der Oberflächenform eines optischen Elements

Die Erfindung betrifft ein Computer-generiertes Hologramm (CGH) sowie ein Verfahren zur Charakterisierung der Oberflächenform eines optischen Elements. Gemäß einem Aspekt weist ein CGH einen wenigstens eine Nutzstruktur (A) aufweisenden ersten Bereich (121, 321, 421) und einen von diesem ersten Bereich (121, 321, 421) räumlich separierten zweiten Bereich (122, 322, 422) auf, wobei dieser zweite Bereich einen Kontrollbereich zur Detektion einer sich auf dem CGH (120, 320, 420, 520) ausbildenden Kontamination bildet.

Polarisationsunabhängiges optisches Kohärenzbereichsreflektometer.

SENSOR SYSTEM

EQUIPMENT AND PROCEDURE FOR THE EXECUTION OF POLARIZATION-BASED QUADRATURE DEMODULATION WITH OPTICAL COHERENCY TOMOGRAPHY

SYSTEM AND PROCEDURE FOR OPTICAL COHERENCY TOMOGRAPHY

VERFAHREN UND VORRICHTUNG ZUR BESTIMMUNG EINES ATHEROSKLEROTISCHEN PLAQUETYPS DURCH MESSUNG VON OPTISCHEN EIGENSCHAFTEN VON GEWEBE

VORRICHTUNG ZUR BESTIMMUNG VON ATHEROSKLEROTISCHEM BELAG DURCH MESSUNG VON OPTISCHEN GEWEBEEIGENSCHAFTEN

Methods for diagnosing vulnerable atherosclerotic plaque using optical coherence tomography to measure tissue optical properties, including backreflectance of heterogeneous layers, such as plaque cap, lipid pool composition and macrophage presence. Methods also include measurement of spatially and temporally dependent reflectance, measurement of multiple wavelength reflectance, low coherence interferometry, polarization and quantification of macrophage content.

PROCEDURE AND DEVICE WITH A TWO-RADIATION INTERFERENCE MICROSCOPE FOR THE INVESTIGATION OF INTEGRATED CIRCUITS AND SUCH A THING.

Apparatus for precise length measurement calibration

Doppler flow imaging using optical coherence tomography

POLARIZATION INDEPENDENT OPTICAL COHERENCE-DOMAIN REFLECTOMETRY

A peristaltic pump providing a mechanism for varying tubing occlusion in combination with a camming mechanism which facilitates opening and closing of the pump and including adjustable screw bearing means for effecting fine adjustments in the position of the occlusion bed to thereby vary the occlusion of the tubing.

Method and apparatus for optimizing optical performance of an interferometer

Image pickup apparatus and image pickup method using optical coherence tomography

Method and system for determining the position of an optical element, machine for laser processing, method for determining pressure and method for determining the temperature of an optical element

A method and a system are described for determining and controlling the separation distance between a processing head of a machine tool and the surface of a material, comprising: - generating a measurement low coherence optical radiation beam, leading the measurement beam towards the material and leading the reflected or diffused measurement beam from the surface of the material towards an optical interferometric sensor arrangement in a first direction of incidence, - generating a reference low coherence optical radiation beam, and leading the reference beam towards the optical interferometric sensor arrangement in a second direction of incidence at a preset angle of incidence with respect to the first direction of incidence of the measurement beam; - superimposing the measurement beam and the reference beam on a common region of incidence of the sensor arrangement; - detecting the position of a pattern of interference fringes between the measurement beam and the reference beam on the region ...

APPARATUS AND METHOD TO PROVE A LEN YOU

Un aparato y método para probar una lente. El aparato comprende una fuente de luz coherente configurada para proporcionar un haz de luz coherente expandido colimado; un primer divisor de haz configurado para dividir el haz de luz coherente expandido colimado que incide sobre este en un primer haz de luz coherente colimado y un segundo haz de luz coherente colimado, donde el primer haz de luz coherente colimado forma un brazo de referencia para medición que prácticamente está ópticamente inalterado desde el primer haz de luz coherente colimado; y el segundo haz de luz coherente colimado forma un brazo de prueba; la longitud del trayecto óptico del brazo de prueba es prácticamente igual a la longitud del trayecto óptico del brazo de referencia; y el brazo de prueba está orientado verticalmente para que la luz lo atraviese en dirección descendente; una cubeta que está ubicada dentro del brazo de prueba y configurada para contener una lente sumergida en una solución de forma tal que mitigue ...

OPTICAL IMAGING SYSTEM BASED ON COHERENCE FREQUENCY DOMAIN REFLECTOMETRY

Provided is an optical imaging system based on a coherence frequency domain reflectometry, including: a light source generating an electromagnetic wave; a splitting unit splitting the electromagnetic wave into first and second beams; a reflecting unit reflecting the first beam and re-transmitting the reflected first beam to the splitter; an objective lens projecting the second beam onto an object to be recorded; a photodetector transforming an interference pattern into a current signal, wherein the first beam reflected from the reflector interferes with the second beam reflected from the object to generate the interference pattern; and an electronic processing unit processing the current signal to generate an image of the object from the interference pattern. Therefore, a lateral resolution can be improved, and Rayleigh limits can be overcome.

METHOD AND APPARATUS FOR PERFORMING OPTICAL MEASUREMENTS USING A RAPIDLY FREQUENCY-TUNED LASER

An external-cavity frequency-tuned laser having a tunable longitudinal cavity mode and a center tunable wavelength includes an optical gain medium positioned within the optical cavity, and a rapid tuning wavelength selecting device positioned to receive light from the optical gain medium and adapted to return selected wavelengths of light to the optical gain medium. The external-cavity frequency-tuned laser is substantially continuously tunable and the tunable wavelength selecting device tunes the center wavelength of the external-cavity frequency-tuned laser at the same rate as the longitudinal cavity mode of the external-cavity frequency-tuned laser is tuned. In another embodiment the optical system includes an interferometer in optical communication with the external-cavity frequency-tuned laser. The interferometer is adapted to project a portion of light from the external-cavity frequency-tuned laser onto a sample and to combine light reflected from the sample and the light from the ...

Interferometry method and system including spectral decomposition

In general, in one aspect, the disclosure features a method that includes directing measurement light to reflect from a measurement surface and combining the reflected measurement light with reference light, where the measurement light and reference light are derived from a common source, and there is a non-zero optical path length difference between the measurement light and reference light that is greater than a coherence length of the measurement light. The method further includes spectrally dispersing the combined light onto a multi-element detector to detect a spatially-varying intensity pattern, determining spatial information about the measurement surface based on the spatially-varying intensity pattern, and outputting the spatial information.

Interferometer that measures aspherical surfaces

A method of manufacturing a projection optical system (37) for projecting a pattern from a reticle to a photosensitive substrate, comprising a surface-shape-measuring step wherein the shape of an optical test surface (38) of an optical element (36) which is a component in the projection optical system is measured by causing interference between light from the optical surface (38) and light from an aspheric reference surface (70) while the optical test surface (38) and said reference surface (70) are held in integral fashion in close mutual proximity. A wavefront-aberration-measuring step is included, wherein the optical element is assembled in the projection optical system and the wavefront aberration of the projection optical system is measured. A surface correction calculation step is also included wherein the amount by which the shape of the optical test surface should be corrected is calculated based on wavefront aberration data obtained at the wavefront-aberration-measuring step and ...

SENSORSYSTEM

Interferometer optical element alignment

Interferometric measuring device

Metrological apparatus and a method of determining a surface characteristic or characteristics

COHERENT TRACKING SENSOR

Interferometric measuring device

INTERFEROMETRIE

PROCEDURE AND DEVICE FOR THE ERROR CORRECTION OF AN HETERODYN INTERFEROMETER

INTERFEROMETER

INTERFEROMETRIC SYSTEM WITH REDUCED VIBRATION SENSITIVITY AND RELATED METHOD

METHOD AND APPARATUS FOR DETERMINATION OF ATHEROSCLEROTIC PLAQUE TYPE BY MEASUREMENT OF TISSUE OPTICAL PROPERTIES

Methods for diagnosing vulnerable atherosclerotic plaque using optical coherence tomography to measure tissue optical properties, including backreflectance of heterogeneous layers, such as plaque cap, lipid pool composition and macrophage presence. Methods also include measurement of spatially and temporally dependent reflectance, measurement of multiple wavelength reflectance, low coherence interferometry, polarization and quantification of macrophage content.

CUVETTE FOR OPHTHALMIC LENS

Modified MZ (Mach-Zender) interferometers are utilized to analyze the tra nsmitted, aspherical wavefront of an ophthalmic lens by mounting the lens in a cuvette having a rotatable carousel that can hold multiple lenses. Fresh, temperature controlled, saline solution is circulated about the lenses, and the cuvette is positioned in a vertical test arm of the interferometer conf iguration. Reverse raytracing is utilized to remove aberrations induced into the wavefront as it is imaged from immediately behind the lens to the detec tor of the interferometer.

SENSOR SYSTEM

A sensor system (10) in an interferometric arrangement has a sensor arm (24) and a reference arm (28). The reference arm (28) is in a stable environment and the sensor arm (24) is arranged to be subject to variations in strain and/or temperature. Radiation from a broadband source (12) propagates through the arrangement and a broadband interferogram is generated as an air gap (114) is scanned. The grammeter is recorded on an oscilloscope (126) and analysed using signal processing software on a computer (128). From the analysis the changes in group delay and optical dispersion of the light in the sensor arm (24) due to strain and temperature changes is measured, and values for the strain and/or temperature changes calculated. A narrowband light source (86) may be used for accurate calibration of path length differences during scanning. The strain and temperature on the sensor arm (24) may be calculated or tested using clamps (30, 32) and a thermal enclosure (34). The system may also be configured ...

Interferometer

METHOD OF COMPENSATING FRINGE ORDER ERROR IN WHITE-LIGHT PHASE-SHIFTING INTERFEROMETRY

The present invention relates to a method of compensating a fringe order error in white-light phase-shifting interferometry, including: an interference signal acquisition step, an index determination step, and a real position calculation step. The interference signal acquisition step includes acquiring at least two color interference signals, using a color camera, from among a red interference signal, a green interference signal, and a blue interference signal. The index determination step includes determining a position where a phase difference between the at least two interference signals reaches a minimum value as an index of the zero order interference signal position. The real position calculation step includes determining, as a zero order interference signal measured position, a position corresponding to the index of the zero order interference signal position from among positions where interference signals are measured from black-and-white interference signals acquired through a ...

THIN FILMS AND SURFACE TOPOGRAPHY MEASUREMENT USING REDUCED LIBRARY

The properties of a surface of an object in presence of thin transparent films are determined by generating a library of model signals and processing a measurement signal via searching the library to evaluate films properties and topography. The library may be reduced with principal component analysis to enhance computation speed. Computation enhancement may also be achieved by removal of the height contributions from the signal leaving only the film contribution in the signal. The film measurement signal is compared to a library of film signals to determine the film parameters of the sample. The library of film signals is produced by processing each full signal in a library to similarly remove the height contributions leaving only the film contributions. Additionally, a post-analysis process may be applied to properly evaluate local topography.

DIFFRACTIVE OPTICAL ELEMENT AND INTERFEROMETRIC MEASURING METHOD

A diffractive optical element (50) with a substrate (52) and a diffractive structure pattern (54) arranged thereon is provided. The diffractive structure pattern is configured to convert a plane or spherical input wave (42) radiated thereon into: 1) at least four separate output waves, wherein at least one of the output waves is a non-spherical wave, at least a further one of the output waves is a spherical wave (58; 70) and at least two further ones of the output waves respectively are a plane wave (60) or a spherical wave (72, 74); 2) at least three separate waves of which at least one is a non-spherical wave and the other two are spherical or planar waves; 3) at least three spherical waves. The diffractive optical element is used in an interferometric method and device for determining the deviations of an actual shape from an intended shape of an optical surface of an optical element. An optical element is fabricated having an optical surface whose deviations from an intended shape, ...

METHOD FOR CALIBRATING AND CORRECTING THE SCANNING DISTORTION OF AN OPTICAL COHERENCE TOMOGRAPHY SYSTEM

Method for calibrating and correcting the scanning distortion of an optical coherence tomography system. Method for calibrating and correcting the scanning distortion of any optical coherence tomography system by using reference patterns and obtaining mathematical relationships between the positions of the reference points in a reference pattern and the local coordinates of said reference points, which coordinates are obtained by means of said optical coherence tomography system.

Interferometry method for ellipsometry, reflectometry, and scatterometry measurements, including characterization of thin film structures

A method including: imaging test light emerging from a test object over a range of angles to interfere with reference light on a detector, wherein the test and reference light are derived from a common source; for each of the angles, simultaneously varying an optical path length difference from the source to the detector between interfering portions of the test and reference light at a rate that depends on the angle at which the test light emerges from the test object; and determining an angle-dependence of an optical property of the test object based on the interference between the test and reference light as the optical path length difference is varied for each of the angles.

Multilayered phantom tissue test structure and fabrication process

A multilayered optical tissue phantom fabrication approach and inherently produced test target structure which address the issues of of optical conformity known in the art by controlling the formation of micrometer scale monolayers embedded with light-scattering microspheres.

Systems and methods for semiconductor chip surface topography metrology

Embodiments of systems and methods for measuring a surface topography of a semiconductor structure are disclosed. In certain examples, a plurality of interference signals, each corresponding to a respective one of a plurality of positions on a surface of the semiconductor structure, are measured. Calibration signals, associated with a baseline region corresponding to a first category of a plurality of categories and a calibrated region corresponding to a second category of the plurality of categories, are measured. A surface height offset, associated with the baseline region and the calibrated region, is determined based on original surface heights and the calibration signals. The original surface heights are determined based on the plurality of interference signals corresponding to the baseline region and the calibrated region. The surface topography of the semiconductor structure is characterized based, at least in part, on the surface height offset and the original surface heights.

System and method for optical coherence tomography

Die Erfindung betrifft ein System sowie ein entsprechendes Verfahren zur optischen Kohärenztomographie mit mindestens einem Interferometer (20) zur Ausgabe von, insbesondere räumlich kurz- oder inkohärentem, Licht, mit dem eine Probe (1) bestrahlt wird, einem Probenarm mit einem Probenobjektiv (41), durch welches vom Interferometer (20) ausgegebenes Licht in einem in der Probe (1) liegenden Fokus fokussiert wird, und einem, vorzugsweise eine Vielzahl von in einer Fläche angeordneten Detektorelementen umfassenden, Detektor zur Erfassung von Licht, welches von der Probe (1) reflektiert wird. Zur zuverlässigen Aufnahme von möglichst scharfen Bildern der Probe (1) ist vorgesehen, während der Erfassung von in unterschiedlichen Tiefen der Probe (1) jeweils reflektiertem Licht die Abbildungseigenschaften des Probenobjektivs (41) zu verändern.

Vorrichtung zur optischen Kohärenztomographie

Vorrichtung (10) zur optischen Kohärenztomographie (OCT), umfassend: eine Signalerfassungseinrichtung (34), die dazu eingerichtet ist, ein Interferenzsignal (G()) für ein abzubildendes Objekt (12) in einem optischen Frequenzbereich () zu erfassen, und eine Rechneranordnung (30), die dazu eingerichtet ist, eine Mehrzahl von Zwischensignalen (G1(k), G2(k)) in einem räumlichen Frequenzbereich (k) aus dem Interferenzsignal (G()) zu ermitteln, wobei jedes der Zwischensignale (G1(k), G2(k)) für eine unterschiedliche Tiefe (z1, z2) des Objekts (12) dispersionskompensiert ist, ein ortsaufgelöstes Abbildungssignal (FFT1, FFT2) für jedes der Zwischensignale (G1(k), G2(k)) durch Anwenden einer Fourier-Transformation auf das jeweilige Zwischensignal (G1(k), G2(k)) zu ermitteln, und ein Tomographiesignal (G(z)) aus den Abbildungssignalen (FFT1, FFT2) zu ermitteln.

Verfahren für die schnelle Datenerfassung bei der Köhärenz-Scanning-Interferometrie

Messeinrichtung zur Durchführung eines Kalibrierverfahrens

Messeinrichtung (10), mit einer Positioniereinheit (20) zum Verfahren eines Messobjekts oder Referenzobjekts (22) in einem Prüfvolumen (24), wobei die Messeinrichtung (10) dazu eingerichtet ist, das folgende Verfahren auszuführen: mit endlicher Genauigkeit und damit Positionierfehler-behaftet erfolgendes Anfahren von verschiedenen, in einem Prüfvolumen (24) der Messeinrichtung (10) liegenden und durch Orts- und/oder Winkelkoordinaten auszeichnungsbaren Kalibrierpositionen, Erzeugen von zur Kalibrierung verwendeten Messsignalen in den jeweiligen Kalibrierpositionen und Bestimmen von Parametern eines Rechenmodells der Messeinrichtung aus den zur Kalibrierung verwendeten Messsignalen und den Orts- und/oder Winkelkoordinaten, wobei ein Koordinatensystem, auf welches sich die Koordinaten aller Positionen innerhalb des Prüfvolumens beziehen, aus fehlerbehaftet angefahrenen Kalibrierpositionen definiert wird, indem exakt sechs Koordinaten von mindestens drei Kalibrierpositionen vorbestimmte Koordinatenwerte ...

VERFAHREN UND VORRICHTUNG ZUR FEHLERKORREKTUR EINES HETERODYN-INTERFEROMETERS

Method for calibrating position measuring system of wafer used for manufacturing semiconductor device, involves applying calibration regulation in position determination during generation of first, second and third measuring signals

The method involves arranging measuring chamber sample stage in movable direction for supporting a sample (4). The structure of a salary linearized is repeatedly measured with the sample table at different pressures of the gaseous medium. The pressure dependence in the performed is determined using the evaluation unit position determination. The calibration regulation is established based on the detected pressure dependency. The calibration regulation is applied in position determination during generation of the first, second and third measuring signals. An independent claim is included for position measuring system.

Surface profiling system

A surface profiler apparatus comprises a light source 4 which is split into two beams by a prism 5: the first beam is directed along a reference path to a reference mirror 6; the second beam passes along a measurement path to a measurement surface 7 of a sample 8. The two paths are then combined and a resulting interference pattern is imaged by detector 10. Moving means (17) allows the measured surface to be moved relative to the reference surface. A set of intensity measurements are taken at intervals along a measurement path and data processing means 32 process the data to determine the position along the measurement path at which predetermined features such as maximum amplitudes occur. This data is used to generate a surface profile of the measured surface which may be used to generate an image upon display 36a. Image enhancement means may be operated by a user. Said means may comprise means for modifying the image in response to intensity gradient data. Different profile heights may ...

INTERFEROMETER FOR THE REGULATION OF CHARACTERISTICS OF AN OBJECT SURFACE

VORRICHTUNG ZUR BESTIMMUNG VON ATHEROSKLEROTISCHEM BELAG DURCH MESSUNG VON OPTISCHEN GEWEBEEIGENSCHAFTEN

Methods for diagnosing vulnerable atherosclerotic plaque using optical coherence tomography to measure tissue optical properties, including backreflectance of heterogeneous layers, such as plaque cap, lipid pool composition and macrophage presence. Methods also include measurement of spatially and temporally dependent reflectance, measurement of multiple wavelength reflectance, low coherence interferometry, polarization and quantification of macrophage content.

MANUAL CALIBRATION OF IMAGING SYSTEM

The invention generally relates to methods for manually calibrating imaging systems such as optical coherence tomography systems. In certain aspects, an imaging system displays an image showing a target and a reference item. A user looks at the image and indicates a point within the image near the reference item. A processer detects an actual location of the reference item within an area around the indicated point. The processer can use an expected location of the reference item with the detected actual location to calculate a calibration value and provide a calibrated image. In this way, a user can identify the actual location of the reference point and a processing algorithm can give precision to the actual location.

COMPENSATION FOR IMPERFECTIONS IN A MEASUREMENT OBJECT AND FOR BEAM MISALIGNMENTS IN PLANE MIRROR INTERFEROMETERS

In one aspect, the invention features a method, including using an interferometer in an interferometry system to produce an output beam comprising a phase related to an optical path difference between a path of a first beam and a path of a second beam, wherein the first beam contacts a measurement object at a first location and the first or second beam contacts the measurement object at a second location, and wherein the first and second locations are different, providing precalibrated information that accounts for contributions to the optical path difference caused by a deviation of the path of the first or second beam from a nominal beam path due to an imperfection of the measurement object at the first location and due to an imperfection of the measurement object at the second location, and determining a position of the measurement object with respect to at least one degree of freedom based on information derived from the output beam and the precalibrated information.

Interferometric measurement of toric surfaces at grazing incidence

Toric surfaces are mounted on a transparent support plate and measured at grazing incidence using a pair of leading and following diffractive optics for diffracting a test beam with respect to a reference beam. The leading diffractive optic diffracts rays of the test beam through various diffraction angles so that after passing through the transparent support plate, the rays strike the toric surface at a constant grazing angle. The following diffractive optic further diffracts the rays of the test beam through other diffraction angles into realignment with the reference beam.

Method for calibrating an interferometer apparatus, for qualifying an optical surface, and for manufacturing a substrate having an optical surface

A method for qualifying and/or manufacturing an optical surface includes: arranging a first substrate having a first surface and a second surface opposite the first surface in a beam path of a first incident beam with the first surface facing towards the first incident beam, and taking an interferometric measurement of the second surface; arranging the first substrate in the beam path of the first incident beam with the second surface facing towards the first incident beam, and taking an interferometric measurement of the second surface; arranging a third surface of a second substrate in a beam path of a second incident beam, and taking an interferometric measurement of the third surface; arranging the third surface of the second substrate and the first substrate in the beam path of the second incident beam, and taking an interferometric measurement of the third surface.

Optical-axis deflection type laser interferometer, calibration method thereof, correction method thereof, and measuring method thereof

An optical-axis deflection type laser interferometer includes a reference ball serving as a measurement reference, a retroreflectingmeans disposed at an object to be measured, a laser interferometer length measuring apparatus that outputs a measurement value according to an increase or a decrease in distance between the apparatus and the retroreflecting means, and a rotational mechanism that rotates a beam projected from the laser interferometer length measuring apparatus around the reference ball. The thus structured laser interferometer measures a distance between the laser interferometer and the retroreflecting means that makes an optical axis of an outgoingbeamproj ected from the laser interferometer length measuring apparatus mounted on the rotational mechanism and an optical axis of a return beam returned to the laser interferometer length measuring apparatus parallel to each other, based on center coordinates of the reference ball. The laser interferometer is characterized by additionally ...

УСТРОЙСТВО ДЛЯ ИЗМЕРЕНИЯ ПАРАМЕТРОВ ФАЗОВЫХ ЭЛЕМЕНТОВ И ДИСПЕРСИИ ОПТИЧЕСКОГО ВОЛОКНА И СПОСОБ ИЗМЕРЕНИЯ ПАРАМЕТРОВ ФАЗОВЫХ ЭЛЕМЕНТОВ И ДИСПЕРСИИ ОПТИЧЕСКОГО ВОЛОКНА

FIELD: physics. SUBSTANCE: group of inventions relates to a device and a method for measuring parameters of phase elements. Device for measuring optical properties of a test element selected from a group comprising phase elements and optical fibres, and the method performed by said device comprises a low-coherent light source connected to an input optical fibre connector which separates light from the low-coherence light source onto the reference arm and the measuring arm, detector configured to receive light from a support arm and a measuring arm, wherein at least one of the support and measuring arms comprises an optical element located on the linear translator, wherein said optical element is selected from a group comprising first and second collimators and a mirror. Device further has a transversely connected second optical fibre connector, a second light source delivering light for the support arm and the measuring arm, and a second detector receiving light from the support arm and the measuring arm, wherein the linear translator is a motorized linear translator, and the second light source is a coherent light source having a coherence length greater than or equal to the motorized linear translator movement range. EFFECT: technical result is measurement of parameters of phase elements and dispersion of phase velocity of optical fibres. 10 cl, 9 dwg РОССИЙСКАЯ ФЕДЕРАЦИЯ (19) RU (11) (13) 2 713 038 C2 (51) МПК G01B 9/02 (2006.01) ФЕДЕРАЛЬНАЯ СЛУЖБА ПО ИНТЕЛЛЕКТУАЛЬНОЙ СОБСТВЕННОСТИ (12) ОПИСАНИЕ ИЗОБРЕТЕНИЯ К ПАТЕНТУ (52) СПК G01B 9/02018 (2019.08); G01M 11/02 (2019.08) (21)(22) Заявка: 2018114296, 30.11.2015 (24) Дата начала отсчета срока действия патента: Дата регистрации: 03.02.2020 18.09.2015 PL P.414064 (43) Дата публикации заявки: 18.10.2019 Бюл. № 29 (73) Патентообладатель(и): ПОЛЬСКИЕ ЦЕНТРУМ ФОТОНИКИ И СВИАТЛОВОДОВ (PL) (45) Опубликовано: 03.02.2020 Бюл. № 4 (85) Дата начала рассмотрения заявки PCT на национальной фазе: 18.04.2018 C 2 PL 2015/050065 (30. ...

Metrological apparatus and a method of determining a surface characteristic or characteristics

A metrological apparatus comprises an optical measurement system (1) such as a coherence scanning interferometer to obtain measurement data representative of a surface of a workpiece and a rotation device (15) to effect relative rotation between the optical measurement system and the workpiece about a measurement axis to enable a plurality of measurement data sets to be obtained with each measurement data set being obtained by the optical measurement system at a respective one of a number of different relative rotational orientations of the optical measurement system and the workpiece. A data corrector (323) is provided to obtain correction data to enable correction of a measurement data set. The correction data may be an average of the plurality of measurement data sets. The measurement data sets may comprise roundness / surface height measurement data. A corresponding method of determining a surface characteristic of a surface of a workpiece is also claimed.

Metrological apparatus and a method of determining a surface characteristic or characteristics

A metrological apparatus comprises an optical measurement system (1) such as a coherence scanning interferometer to obtain measurement data representative of a surface of a workpiece and a rotation device (15) to effect relative rotation between the optical measurement system and the workpiece about a measurement axis to enable a plurality of measurement data sets to be obtained with each measurement data set being obtained by the optical measurement system at a respective one of a number of different relative rotational orientations of the optical measurement system and the workpiece. A data corrector (323) is provided to obtain correction data to enable correction of a measurement data set. The correction data may be an average of the plurality of measurement data sets. The measurement data sets may comprise roundness / surface height measurement data. A corresponding method of determining a surface characteristic of a surface of a workpiece is also claimed. Further claimed is a method ...

Interferometer with air turbulence compensation

AN ARTIFACT FOR DETERMINING RESOLUTION OF IMAGING BASED ON ELECTROMAGNETIC RADIATION AND/OR MECHANICAL WAVES

An artifact (101) for determining resolution of imaging based on electromagnetic radiation, mechanical waves, or both is presented. The artifact comprises a substrate (102) and layers (103, 104) on top of the substrate. The layers comprise organic material and are stacked on each other in a partially overlapping way so that an edge (107) of a first one of the layers is arranged to intersect with an edge (108) of a second one of the layers. The layers constitute a three-dimensional surface topography where a groove (111) defined by the edges of the first and second ones of the layers is tapering towards a point of intersection (112) between the edges. The resolution is a minimum width of the tapering groove which is revealed by the imaging so that a pre-determined criterion is fulfilled.

INTERFEROMETRY TESTING OF LENSES, AND SYSTEMS AND DEVICES FOR SAME

Modified MZ (Mach-Zender) interferometers preferably are utilized to anal yze the transmitted, aspherical wavefront of an ophthalmic lens by mounting the lens in a cuvette having a rotatable carousel that can hold multiple len ses. Fresh, temperature controlled, saline solution is circulated about the lenses, and the cuvette is positioned in a vertical test arm of the interfer ometer configuration. Reverse raytracing preferably is utilized to remove ab errations induced into the wavefront as it is imaged from immediately behind the lens to the detector of the interferometer.

Generating model signals for interferometry

A method is disclosed which includes, for each of multiple areas of a test surface on a test object having different reflectivities, using an interferometry system to measure each area in a first mode of operation that measures information about the reflectivity of the area over a range of angles and wavelengths; using the same interferometry system to measure the test surface in a second mode ofoperation that interferometrically profiles a topography of the test surface over a range including at least some of the multiple areas; and correcting the profile based on the information about the reflectivity of the multiple areas to reduce errors.

MEASUREMENT OF LIGHT RETRO-REFLECTED BY AN OPTICAL INSTRUMENT

Calibration of scanning interferometers

Calibrating a scanning interferometry imaging system includes: configuring the scanning interferometry imaging system for operation with an interference objective using light having a narrowband wavelength spectrum; using the scanning interferometry imaging system to direct measurement light and reference light along different paths and to overlap the measurement and reference light on a detector, the measurement and reference light having the narrowband wavelength spectrum; scanning an optical path length difference between the measurement light and the reference light at the detector while acquiring intensity data using the detector, the detector acquiring the intensity data at a frame rate and the scanning being performed at a scan speed; determining information about the scan speed based on the acquired intensity data, geometric information about the scanning interferometry imaging system, and the narrowband wavelength spectrum; and calibrating the scanning interferometry imaging system ...

ELECTRONICALLY MODULATED DYNAMIC OPTICAL PHANTOMS FOR BIOMEDICAL IMAGING

A method and system for calibrating an optical tomographic imaging system that is configured to execute time-series optical measurements of a target's response to incident optical energy is presented. An electro-active device that is configured to be electronically modulated to control the electro-active device's opacity is embedded in a dense scattering medium. A known hemodynamic response pattern is selected and at least one wavelength of optical energy that produces the known hemodynamic response pattern is determined. A wavelength-dependent driving voltage function is then computed. A voltage is then applied to the electro-active device according to the wavelength-dependent driving voltage function. Optical energy is then transmitted to the scattering medium at the at least one wavelength and a hemodynamic response for the target is determined. The known hemodynamic response pattern and the determined hemodynamic response pattern are then compared.

Two beam interference objective device

Width and direction of interference fringes of a two beam interference objective device can be adjusted with a single hand, thereby improving operability and work efficiency. The two beam interference objective device includes an objective lens (1), a prism (12) provided between the objective lens (1) and a sample (4), a reference mirror (13) provided to one of light-paths divided by the prism (12), and a tilting device (14) for tilting the reference mirror (13) to adjust the width and direction of the interference fringes. The tilting device (14) includes a width adjuster (41) for pivotally moving the reference mirror (13) centering an axis parallel to an optical axis of the objective lens (1) while keeping a distance from the optical axis of the objective lens (1) to the reference mirror (13), and a direction adjuster (51) for turning the reference mirror (13) centering the one of divided optical paths.

Positioning stage device

A high speed, wide-range, high-accuracy positioning stage device for eliminating errors due to deterministic elements such as variation of surface machining accuracy of a bar mirror and for preventing error accumulation due to indeterminate elements such as air fluctuations when switching between laser interferometers. When an X1 laser interferometer as a first position measurement device and an X2 laser interferometer as a second position measurement device are switched, at a place at which at least two position measurement devices are activated, when a value is handed over from the X1 laser interferometer, which was activated, to the X2 laser interferometer, which is to be activated, errors due to the effect of X-bar mirror flatness and air fluctuations are found by a correction function for the X-bar mirror and/or a table and the average of the measured values, and the value of the X2 laser interferometer is corrected by a correction device such as a calculation device.

Surface profiling apparatus

Light is directed along a sample path towards the sample surface and along a reference path towards a reference surface such that light reflected by the sample surface and light reflected by the reference surface interfere. Relative movement is effected between the sample surface and the reference surface along a measurement path and the light intensity resulting from interference between light reflected from the reference surface and regions of the sample surface is sensed at intervals along the measurement path to provide a number of sets of light intensity data values with each light intensity data value representing the sensed light intensity associated with a corresponding one of said regions. The sets of light intensity data are processed to determine a position along the measurement path at which a predetermined feature occurs in the light intensity data for each sensed region and to enhance image data representing the intensity data to facilitate the detection by a user of the interference ...

Method for absolute calibration of an interferometer

In the case of a method for absolute calibration of an interferometer with the aid of a spherical output wave, comprising an optical element which retroflects the incident spherical wave itself or via a mirror, at least four measuring procedures are undertaken to determine a wave aberration W. The optical element is measured in the at least four measuring positions intrafocally and extrafocally in at least two different rotational angle positions. It is also possible, in addition, to undertake a measurement via a mirror in the cat's eye position (focus 3).

Method and apparatus for optically analyzing a surface

A method and apparatus for analyzing a surface of a test object employs apparatus with a scanning interferometry system which generates a windowed interferometric signal from the surface of a test object to characterize the surface of the test object.

In situ calibration of interferometers

In-situ calibration of an interferometer includes making a sequence of phase measurements of a test object using the interferometer, each of the measurements having a same carrier fringe frequency, where at least some of the measurements are made at three or more different orientations of carrier fringes, and determining information about the test object based on at least some of the phase measurements, in which determining the information includes reducing errors in the measurements arising from imperfections in the interferometer based on the measurements made at the three or more different orientations.

CALIBRATION JIG FOR OPTICAL TOMOGRAPHIC IMAGING APPARATUS AND METHOD FOR GENERATING A CALIBRATION CONVERSION TABLE

A calibration jig allowing simple and repeatable calibration of a probe optical tomographic apparatus is disclosed. The jig includes a holding member removably attachable to an attachment section of the apparatus and a reflective surface held by the holding member. The reflective surface reflects measurement light emitted from an emitting section of the attachment section and directs reflected light back to the emitting section. If a probe of the apparatus is covered with a sheath, the jig may include a light transmitting member, which generates the same dispersion as dispersion at the sheath, between the emitting section and the reflective surface. The reflective surface may be a single reflective surface disposed within an area corresponding to twice a coherence length of the laser light with a zero path position of the reflective surface being the center of the area. 1. A method for generating a calibration conversion table using a calibration jig for calibrating an optical tomographic imaging apparatus ,the calibration jig including a holding member removably attachable to an attachment section of the optical tomographic imaging apparatus, and a reflective surface held by the holding member, the reflective surface reflecting measurement light emitted from an emitting section of the attachment section and directing reflected light back to the emitting section,the calibration conversion table representing a relationship between wavenumber and time and being used for converting a first interference signal plotted along a time axis with constant time intervals into a second interference signal plotted along a wavenumber axis with constant wavenumber intervals,the first interference signal being obtained by: attaching the calibration jig to the attachment section to optically couple the calibration jig to the apparatus in a removable manner; emitting laser light from a frequency-swept laser light source with temporally swept optical frequency; dividing the laser ...

Method of measuring a shape of an optical surface based on computationally combined surface region measurements and interferometric measuring device

Measuring a shape of an optical surface ( 14 ) of a test object ( 12 ) includes: providing an interferometric measuring device ( 16 ) generating a measurement wave ( 18 ); arranging the measuring device ( 16 ) and the test object ( 12 ) consecutively at different measurement positions relative to each other, such that different regions ( 20 ) of the optical surface ( 14 ) are illuminated by the measurement wave ( 18 ); measuring positional coordinates of the measuring device ( 16 ) at the different measurement positions in relation to the test object ( 12 ); obtaining surface region measurements by interferometrically measuring the wavefront of the measurement wave ( 18 ) after interaction with the respective region ( 20 ) of the optical surface ( 14 ) using the measuring device ( 16 ) in each of the measurement positions; and determining the actual shape of the optical surface ( 14 ) by computationally combining the sub-surface measurements based on the measured positional coordinates of the measuring device ( 16 ) at each of the measurement positions.

Position monitoring system with reduced noise

An interferometry system for monitoring changes in the position of an object, the system includes a spectrally broadband light source, a sensor module having an interferometer that direct portions of the light received from the source along separate paths. The system includes an intensity monitor having a detector configured to measure the intensity of additional light derived from the source and to produce a monitor output signal. The system includes an electronic processing module to process a sensor output signal based on the monitor output signal to account for intensity fluctuations in light output by the source, and determine information about the changes in the position of the object. The intensity monitor is configured to characterize the intensity fluctuations as a function of wavelength or intensity fluctuations that are spectrally correlated.

FREQUENCY-DOMAIN INTERFEROMETRIC BASED IMAGING SYSTEMS AND METHODS

Systems and methods for improved interferometric imaging are presented. One embodiment is a partial field frequency-domain interferometric imaging system in which a light beam is scanned in two directions across a sample and the light scattered from the object is collected using a spatially resolved detector. The light beam could illuminate a spot, a line or a two-dimensional area on the sample. Additional embodiments with applicability to partial field as well as other types of interferometric systems are also presented. 144-. (canceled)45. A frequency-domain interferometric imaging system for imaging a light scattering object comprising:a light source for generating a light beam;a beam divider for separating the light beam into reference and sample arms, wherein the sample arm contains the light scattering object to be imaged;sample optics for delivering the light beam in the sample arm to the light scattering object to be imaged, the light beam in the sample arm defining a line beam illuminating a linear area spanning a plurality of A-scan locations on the light scattering object at the same time, the linear area defining a first linear field of view (FOV), the sample optics including a beam scanner for scanning the line beam in a direction parallel to, and along, the line beam in the sample arm, so that the linear area is moved to illuminate the object at a plurality of locations defining a scan line having a second linear FOV longer than the first linear FOV;a detector having a plurality of photosensitive elements defining a light-capturing region including a plurality of spatially resolvable A-scan capturing locations arranged to simultaneously capture the plurality of A-scan locations spanned by the linear area, allowing the plurality of A-scan locations to be captured at the same time in parallel with the plurality of photosensitive elements;return optics for combining light scattered from the object and light from the reference arm and directing the ...

Calibration apparatus, calibration method, and measurement apparatus

The present invention provides a calibration apparatus for calibrating an optical apparatus, which has a scanning member and scans light on an object by rotating the scanning member, including a target member including a region irradiated with light from the scanning member, an obtaining unit configured to obtain a light amount of light reflected by the region, and a processing unit configured to execute processing for calculating a calibration value required to calibrate a rotation angle of the scanning member, wherein the region is configured to be nonplanar so that a light amount obtained by the obtaining unit changes according to a light irradiation position.

CALIBRATION METHOD

A calibration method includes the steps of placing a structure to be measured at a first position, measuring a first distance from a laser interferometer to a reflector, and measuring first coordinates of a body to be measured, moving the structure to be measured to a second position, measuring a second distance from the laser interferometer to the reflector and measuring second coordinates of the structure to be measured with the coordinate measuring apparats, while the structure to be measured is at the second position, determining a scale error of the reference instrument, mounting the reference instrument, measuring the interval between objects to be measured, and calculating a calibration value of the interval between the objects to be measured. 1. A calibration method for calibrating , with a coordinate measuring apparatus , an interval between a plurality of objects to be measured in a reference instrument , the method comprising the steps of:placing a structure to be measured used for measuring a scale error of the coordinate measuring apparatus at a first position in a measurement direction of the scale error, the structure to be measured including a body to be measured and a reflector connected to the body to be measured;measuring a first distance from a laser interferometer to the reflector by having the laser interferometer irradiate the reflector with a laser beam in the measurement direction, and measuring first coordinates in the measurement direction of the body to be measured with the coordinate measuring apparatus, while the structure to be measured is at the first position;moving the structure to be measured in the measurement direction to a second position different from the first position;measuring a second distance from the laser interferometer to the reflector by having the laser interferometer irradiate the reflector with the laser beam in the measurement direction, and measuring second coordinates in the measurement direction of the body to ...

SYSTEMS AND METHODS FOR SEMICONDUCTOR CHIP SURFACE TOPOGRAPHY METROLOGY

Embodiments of systems and methods for measuring a surface topography of a semiconductor structure are disclosed. In certain examples, a plurality of interference signals, each corresponding to a respective one of a plurality of positions on a surface of the semiconductor structure, are measured. Calibration signals, associated with a baseline region corresponding to a first category of a plurality of categories and a calibrated region corresponding to a second category of the plurality of categories, are measured. A surface height offset, associated with the baseline region and the calibrated region, is determined based on original surface heights and the calibration signals. The original surface heights are determined based on the plurality of interference signals corresponding to the baseline region and the calibrated region. The surface topography of the semiconductor structure is characterized based, at least in part, on the surface height offset and the original surface heights. 1. A method for measuring a surface topography of a semiconductor structure , comprising:measuring, by an interferometer, a plurality of interference signals each corresponding to a respective one of a plurality of positions on a surface of the semiconductor structure;measuring calibration signals associated with a baseline region corresponding to a first category of a plurality of categories and a calibrated region corresponding to a second category of the plurality of categories, the plurality of categories being obtained according to classification of a plurality of spectrum signals each corresponding to the respective one of the plurality of positions on the surface of the semiconductor structure or classification of the plurality of interference signals, and each of the plurality of categories corresponding to a region having a same material on the surface of the semiconductor structure;determining, by at least one processor, a surface height offset, associated with the baseline ...

OPTICAL SYSTEM, OPTICAL DEVICE, AND PROGRAM

An optical system includes a polarized light phase shift optical circuit that includes a polarizing beam splitter that splits light having a coherence length shorter than a difference in optical path length between a normal optical path and a delay optical path having an optical path length longer than the normal optical path, the light being split into normal light, which travels along the normal optical path, and delay light, which travels along the delay optical path; a separator where the normal light and the delay light are individually emitted at a reference flat and the separator divides the reflected light that reflects off the reference flat into a plurality of light beams; and a plurality of image capture elements that respectively detect the intensities of the plurality of divided light beams, and the optical system also includes an information processor that includes a calibrator. 1. An optical system comprising:a polarized light phase shift optical circuit; andan information processor that processes data detected by the polarized light phase shift optical circuit, wherein: a polarizing beam splitter that splits light having a coherence length shorter than a difference in optical path length between a normal optical path and a delay optical path having an optical path length longer than the normal optical path, the light being split into normal light, which travels along the normal optical path, and delay light, which travels along the delay optical path;', 'a separator where the normal light and the delay light are individually emitted at a reference flat and the separator divides the reflected light that reflects off the reference flat into a plurality of light beams; and', 'a plurality of image capture elements that respectively detect the intensities of the plurality of divided light beams,, 'the polarized light phase shift optical circuit comprises 'a calibrator that individually identifies calibration parameters for calibrating optical ...

CALIBRATION OF SCANNING INTERFEROMETERS

Calibrating a scanning interferometry imaging system includes: configuring the scanning interferometry imaging system for operation with an interference objective using light having a narrowband wavelength spectrum; using the scanning interferometry imaging system to direct measurement light and reference light along different paths and to overlap the measurement and reference light on a detector, the measurement and reference light having the narrowband wavelength spectrum; scanning an optical path length difference between the measurement light and the reference light at the detector while acquiring intensity data using the detector, the detector acquiring the intensity data at a frame rate and the scanning being performed at a scan speed; determining information about the scan speed based on the acquired intensity data, geometric information about the scanning interferometry imaging system, and the narrowband wavelength spectrum; and calibrating the scanning interferometry imaging system based on the information about the scan speed. 1. A method of calibrating a scanning interferometry imaging system , comprising:configuring the scanning interferometry imaging system for operation with an interference objective using light having a narrowband wavelength spectrum;using the scanning interferometry imaging system to direct measurement light and reference light along different paths and to overlap the measurement and reference light on a detector, the measurement and reference light having the narrowband wavelength spectrum;scanning an optical path length difference between the measurement light and the reference light at the detector while acquiring intensity data using the detector, the detector acquiring the intensity data at a frame rate and the scanning being performed at a scan speed;determining information about the scan speed based on the acquired intensity data, geometric information about the scanning interferometry imaging system, and the narrowband ...

IN SITU CALIBRATION OF INTERFEROMETERS

In-situ calibration of an interferometer includes making a sequence of phase measurements of a test object using the interferometer, each of the measurements having a same carrier fringe frequency, where at least some of the measurements are made at three or more different orientations of carrier fringes, and determining information about the test object based on at least some of the phase measurements, in which determining the information includes reducing errors in the measurements arising from imperfections in the interferometer based on the measurements made at the three or more different orientations. 1. An interferometer system comprising:a detector configured to obtain interferometry data from a test object surface; obtain a sequence of phase map measurements of the test object from the detector, each of the measurements having a same carrier fringe frequency, where at least some of the measurements are made at three or more different orientations of carrier fringes; and', 'determine information about the test object based on at least some of the phase map measurements, wherein determining the information comprises reducing errors in the measurements arising from imperfections in the interferometer system based on the measurements made at the three or more different orientations., 'a data processing apparatus coupled to the detector, the data processing apparatus being configured to2. The interferometer system of claim 1 , further comprising an adjustable aperture stop claim 1 , wherein the data processing apparatus is further configured to control a position of the adjustable aperture stop to provide the different orientations of the carrier fringes.3. The interferometer of claim 2 , wherein the adjustable aperture stop comprises a first opening for passing a first beam reflected from the test object and a second opening for passing a second beam reflected from a reference surface.4. The interferometer of claim 3 , further comprising an alignment detector ...

Calibration jig for optical tomographic imaging apparatus and method for generating a calibration conversion table

A calibration jig allowing simple and repeatable calibration of a probe optical tomographic apparatus is disclosed. The jig includes a holding member removably attachable to an attachment section of the apparatus and a reflective surface held by the holding member. The reflective surface reflects measurement light emitted from an emitting section of the attachment section and directs reflected light back to the emitting section. If a probe of the apparatus is covered with a sheath, the jig may include a light transmitting member, which generates the same dispersion as dispersion at the sheath, between the emitting section and the reflective surface. The reflective surface may be a single reflective surface disposed within an area corresponding to twice a coherence length of the laser light with a zero path position of the reflective surface being the center of the area.

METHOD AND APPARATUS FOR MOTION COMPENSATION IN INTERFEROMETRIC SENSING SYSTEMS

An optical interrogation system, e.g., an OFDR-based system, measures local changes of index of refraction of a sensing light guide subjected to a time-varying disturbance. Interferometric measurement signals detected for a length of the sensing light guide are transformed into the spectral domain. A time varying signal is determined from the transformed interferometric measurement data set. A compensating signal is determined from the time varying signal which is used to compensate the interferometric measurement data set for the time-varying disturbance. The compensation technique may be applied along the length of the light guide. 1. An optical interrogation system for measuring a parameter of a sensing light guide subjected to a time-varying disturbance , the optical interrogation system comprising:an optical interferometric interrogator;optical detection circuitry coupled to the optical interferometric interrogator, the optical detection circuitry for detecting interferometric measurement signals for a length of the sensing light guide, where the sensing light guide includes a series of segments with corresponding segment locations along the length of the sensing light guide; and receiving the interferometric measurement signals from the optical detection circuitry,', 'generating a measurement data set based on the interferometric measurement signals, the measurement data set including a plurality of data segments corresponding to the series of segments;', 'transforming one or more data segments of the plurality of data segments into a spectral domain to produce one or more transformed data segments;', 'extracting a phase signal from the one or more transformed data segments;', 'determining a compensating signal from the phase signal; and', 'using the compensating signal to compensate at least some portion of the measurement data set for the time-varying disturbance., 'data processing circuitry configured to perform operations comprising2. The optical ...

Thickness evaluation method of cell sheet

A thickness evaluation method of the cell sheet according to the invention includes tomographically imaging a cell sheet by optical coherence tomography and obtaining a thickness distribution of the cell sheet based on a result of the tomography imaging. A tomographic image corresponding to one cross section of the cell sheet is obtained by tomography imaging while scanning the light in a main scanning direction. The tomography imaging is performed in every time while moving an incident position of the light at a predetermined feed pitch in a sub-scanning direction, thereby a plurality of the tomographic images corresponding to a plurality of cross-sections are obtained. One-dimensional thickness distributions of the cell sheet in the corresponding cross-sections are obtained based on each of the plurality of tomographic images, and a two-dimensional thickness distribution of the cell sheet is obtained by interpolating the one-dimensional thickness distributions.

METHOD FOR CALIBRATING A MEASURING DEVICE

The invention relates to a method for calibrating a measuring device, comprising the following steps: moving, with finite accuracy and thus with positioning error, to various points that lie in a testing volume of the measuring device and that can be characterized by spatial and/or angular coordinates, generating measurement signals at the respective points, and determining parameters of a computing model of the measuring device from the measurement signals and the spatial and/or angular coordinates. The method is characterized in that a coordinate system to which the coordinates of the points of the testing volume relate is defined from points moved to with error, by associating predetermined coordinate values with exactly six coordinates of three points. 110. Method for calibrating a measuring device () , the method comprising:{'b': '24', 'moving, with finite accuracy and thus with positioning error, to various measuring positions located in a testing volume () of the measuring device and distinguishable by spatial and/or angular coordinates,'}generating measurement signals at the respective measuring positions, anddetermining parameters of a mathematical model of the measuring device from the measurement signals and the spatial and/or angular coordinates, including deriving a coordinate system, to which coordinates of points of the testing volume relate, from the measuring positions moved to with error by associating predetermined coordinate values with exactly six coordinates of at least three of the measuring positions.210. Method for calibrating a measuring device () , the method comprising:{'b': '24', 'moving, with finite accuracy and thus with positioning error, to various measuring positions located in a testing volume () of the measuring device and distinguishable by spatial and/or angular coordinates,'}generating measurement signals at the respective measuring positions, anddetermining parameters of a mathematical model of the measuring device from the ...

OCT system calibration method for improved image resolution and reduced image artifacts

Methods and systems for increasing resolution and mitigating sidelobe artifacts on point spread functions in optical coherence tomography systems by addressing (1) the swept source's power variation across the scan band, (2) errors in sampling instances, and (3) window function selection. 1. A method for calibrating and processing A-lines in an optical coherence tomography system , the method comprising:measuring a response of the system of a calibration fixture; andperforming spectral flattening of subsequent A-lines taken from a sample in response to the measured response of the calibration fixture.2. A method as claimed in claim 1 , wherein the calibration fixture includes a mirror.3. A method as claimed in claim 1 , further comprising resampling the A-lines.4. A method as claimed in claim 3 , wherein resampling comprises performing fractional sample correction of A-lines.5. A method as claimed in claim 3 , further comprising performing band-limited interpolation prior to resampling.6. A method as claimed in claim 3 , wherein the resampling is based on measuring the response of the system to the calibration fixture.7. A method as claimed in claim 1 , further comprising performing multi window processing of the A-lines.8. A method as claimed in claim 7 , wherein multi window processing includes employing parameterized windows.9. A method as claimed in claim 7 , wherein the windows include Kaiser-Bessel claim 7 , Dolph-Chebyshev claim 7 , or adjustable windows.10. A method for processing A-lines in an optical coherence tomography system claim 7 , comprising:obtaining A-lines from a sample; andperforming multi window processing of the A-lines.11. An optical coherence tomography system claim 7 , comprising:a sample interferometer;a digital acquisition system for digitizing A-lines from the sample interferometer;a calibration fixture for the sample interferometer; andan image processing computer for performing spectral flattening of A-lines taken from a sample in ...

Automated re-focusing of interferometric reference mirror

A reference surface is used to develop an empirical plot between a parameter of interest, such as roughness or modulation, and the position of the reference mirror in an interferometer by repeating measurements of the reference surface at different positions of the reference mirror so as to identify the in-focus position of the reference mirror. Serial quality-control measurements of samples of interest are carried out with the reference mirror in such in-focus position until a predetermined quality-control event triggers an automated system re-calibration by re-measuring the reference surface and, if the result does not correspond to the in-focus position of the reference mirror according to the plot, by finding a new in-focus position for the reference mirror using the same plot or, alternatively, a new similarly produced plot. Sample measurements are then resumed with the mirror placed at that new position.

METHOD AND APPARATUS FOR OPTIMIZING THE OPTICAL PERFORMANCE OF INTERFEROMETERS

A method for measuring a property of a test object with an interferometer includes: a) providing calibration information relating a focus setting for the interferometer to a position of the test object relative to a reference surface of the interferometer; b) determining the position of the test object relative to the reference surface; and c) using the interferometer to collect interferometric images of the test object for use in measuring the property of the test object. 1. A method for measuring a property of a test object with an interferometer , the method comprising:a. providing calibration information relating a focus setting for the interferometer to a position of the test object relative to a reference surface of the interferometer;b. determining the position of the test object relative to the reference surface; andc. using the interferometer to collect interferometric images of the test object for use in measuring the property of the test object; i. prior to collecting at least some of the interferometric images, adjusting a focus of the interferometer in hardware based on the calibration information and the determined position of the test object relative to the reference surface to improve a degree of focus of the interferometric images; and', 'ii. using one or more electronic processors to mathematically propagate at least one wavefront derived from the interferometric images based on the calibration information and the determined position of the test object relative to the reference surface to improve a degree of focus of the wavefront derived from the interferometric images., 'd. wherein the method further comprises at least one of the following2. The method of claim 1 , wherein the interferometer comprises a ruled stage for supporting the test object and wherein determining the position of the test object relative to the reference surface comprises manually or automatically reading the ruled stage.3. The method of claim 1 , wherein the interferometer ...

Microscope

A microscope is provided which includes an optical module, an OCT module, and a control device. The optical module is configured to generate optical image representations. The OCT module is configured to generate tomographic recordings. The control device is configured to determine the relative spatial position of a marking element, in each case from an optical image representation of the marking element and from a tomographic recording of the same marking element.

OPTICAL PHASE MEASUREMENT METHOD AND SYSTEM

A measurement system for use in measuring parameters of a patterned sample, the system including a broadband light source, an optical system configured as an interferometric system, a detection unit, and a control unit, where the interferometric system defines illumination and detection channels having a sample arm and a reference arm having a reference reflector, and is configured for inducing an optical path difference between the sample and reference arms, the detection unit for detecting a combined light beam formed by a light beam reflected from the reflector and a light beam propagating from a sample's support, and generating measured data indicative of spectral interference pattern formed by spectral interference signatures, and the control unit for receiving the measured data and applying a model-based processing to the spectral interference pattern for determining one or more parameters of the pattern in the sample. 1. A measurement system for use in measuring parameters of a patterned sample , the system comprising:a broadband light source;an optical system configured as an interferometric system;a detection unit; anda control unit, the interferometric system defines illumination and detection channels having a sample arm and a reference arm comprising a reference reflector, and is configured for inducing an optical path difference between the sample and reference arms,', "the detection unit is configured and operable for detecting a combined light beam formed by a light beam reflected from said reflector and a light beam propagating from a sample's support, and generating measured data indicative of spectral interference pattern formed by at least two spectral interference signatures, and", 'said control unit is configured and operable for receiving the measured data and applying a model-based processing to the spectral interference pattern for determining one or more parameters of the pattern in the sample., 'wherein'}2. An optical system for use in ...

DYNAMICAL MODELING OF CMMS FOR NUMERICALLY CORRECTING MEASUREMENT RESULTS

A computer program product for numerically correcting an endpoint position of a Coordinate Measuring Machine (CMM) implemented on a computing unit, receiving as input temporally resolved information from a set of sensors attached to or integrated into the CMM, and to a method for numerically correcting an endpoint position of a CMM, wherein errors between a targeted endpoint position and an actual endpoint position reached during a measurement process are numerically compensated through the use of the computer program product. 1. A computer program product for numerically correcting an endpoint position of a Coordinate Measuring Machine (CMM) implemented on a computing unit configured to perform a series of operations when the computer program product is executed on the computing unit , the operations comprising: temporally resolved information from a set of sensors attached to or integrated into the CMM,', 'temporally resolved information about component parts physically constituting the CMM as well as their mechanical properties,', 'a set of possible models, each with a potentially different set of free parameters, for modelling the constituting component parts of the CMM,', 'set of possible models, each with a potentially different set of free parameters, for fusing the constituting component models into a model for the whole CMM, and', 'alibration information for adapting the free parameters of the constituting component models and the fusion models from some initially known nominal values of the free parameters,, 'receiving as inputperforming a simulation of the behavior of the CMM, the simulation being based on the temporally resolved information from the sensors attached to the CMM and the temporally resolved knowledge of the physical components constituting the CMM as well as their mechanical properties, the simulating including time-adaptive physical modelling of the CMM, such that the models for the constituting component parts of the CMM and the fusion ...

MANUAL CALIBRATION OF IMAGING SYSTEM

The invention generally relates to methods for manually calibrating imaging systems such as optical coherence tomography systems. In certain aspects, an imaging system displays an image showing a target and a reference item. A user looks at the image and indicates a point within the image near the reference item. A processer detects an actual location of the reference item within an area around the indicated point. The processer can use an expected location of the reference item with the detected actual location to calculate a calibration value and provide a calibrated image. In this way, a user can identify the actual location of the reference point and a processing algorithm can give precision to the actual location. 1. An imaging system , comprising:an intravascular imaging catheter configured to be positioned within a vessel of a patient; and receive, from the intravascular imaging catheter, a first image including the vessel and a reference item;', 'output, to a display in communication with the processor, the first image including the vessel and the reference item;', 'receive a user input to move the displayed reference item from a first position to a second position;', 'determine a calibration value based on a difference between the first position and the second position;', 'generate, based on the calibration value, a second image of the vessel; and', 'output, to the display, the second image of the vessel., 'a processor configured for communication with the intravascular imaging catheter, wherein the processor is configured to2. The system of claim 1 , wherein the reference item comprises a structure of the intravascular imaging catheter disposed within the vessel.3. The system of claim 2 , wherein the reference item comprises a catheter sheath.4. The system of claim 1 , wherein the calibration value comprises a z-offset associated with an interferometric device.5. The system of claim 1 ,wherein the user input comprises a start and an end, andwherein the ...

DISTANCE MEASURING DEVICE AND METHOD FOR MEASURING DISTANCES

A distance measuring device for measuring a distance to an object to be measured comprises a beam splitter for splitting broadband coherent light emitted by a light source in measuring light which is guided through an object arm to the object to be measured and in reference light which is guided to a reference arm. A focusing optics with a focus being movable along an optical axis of the object arm is provided in the object arm, wherein the focusing optics comprises a movable optical element and is configured such that a movement of the movable optical element along the optical axis causes a higher movement of the focus of the focusing optics along the optical axis and wherein the movable optical element of the focusing optics is coupled to the reference arm such that the optical path length of the reference arm can be tracked synchronously with and dependent on the movement of the focus of the focusing optics. 1. A distance measuring device for measuring a distance to an object to be measured , comprising:a beam splitter for splitting broadband coherent light emitted by a light source in measuring light being guided through an object arm to the object to be measured and in reference light being guided to a reference arm,wherein a focusing optics with a focus being movable along an optical axis of the object arm is provided in the object arm and wherein the focusing optics comprises a movable optical element and is configured such that a movement of the movable optical element along the optical axis causes a higher movement of the focus of the focusing optics along the optical axis andwherein the movable optical element of the focusing optics is coupled to the reference arm such that the optical path length of the reference arm can be tracked synchronously with and dependent on the movement of the focus of the focusing optics.2. The distance measuring device according to claim 1 , wherein the movable optical element is configured as a lens being movable along the ...

CALIBRATION OF AN INTERFEROMETER

In a method for calibrating an interferometer () having a beam path for a measuring beam (), wherein at least one plane () that at least partially reflects the measuring beam () has been introduced into the beam path, and wherein a normal to a first plane () is inclined at a first angle to a measuring beam () incident on the first plane (), the following steps are carried out: interferometric measurement of a first axial spacing of a first point on the first plane () with the measuring beam (), and interferometric measurement of a second axial spacing of a second point on one of the at least one plane () with the measuring beam (), wherein the second point is spaced apart from the first point. 121-. (canceled)22. A method for calibrating an interferometer having a beam path for a measuring beam , wherein at least one plane that at least partially reflects the measuring beam has been introduced into the beam path , and wherein a normal to a first plane is inclined at a first angle to a measuring beam incident on the first plane and wherein the following steps are carried out:a. interferometric measurement of a first axial spacing of a first point on the first plane with the measuring beam;b. interferometric measurement of a second axial spacing of a second point on one of the at least one plane with the measuring beam, wherein the second point is spaced apart from the first point.23. The method according to claim 22 , wherein the first plane has a planarity which is below the measurement accuracy of the interferometer.24. The method according to claim 22 , wherein a measuring lens is positioned from a first position claim 22 , for measuring an object in the measuring position claim 22 , to a second position for calibrating the interferometer claim 22 , such that the measuring lens is directed at the first plane.25. The method according to claim 22 , wherein claim 22 , in order to measure the second spacing claim 22 , the measuring beam is displaced laterally by a ...

REDUCING REGISTRATION ERROR OF FRONT AND BACK WAFER SURFACES UTILIZING A SEE-THROUGH CALIBRATION WAFER

A calibration wafer and a method for calibrating an interferometer system are disclosed. The calibration method includes: determining locations of the holes defined in the calibration wafer based on two opposite intensity frame; comparing the locations of the holes against the locations measured utilizing an external measurement device; adjusting a first optical magnification or a second optical magnification at least partially based on the comparison result; defining a first distortion map for each of the first and second intensity frames based on the comparison of the locations of the holes; generating an extended distortion map for each of the first and second intensity frames by map fitting the first distortion map; and utilizing the extended distortion map for each of the first and second intensity frames to reduce at least one of: a registration error or an optical distortion in a subsequent measurement process. 1. An interferometer system , comprising:first and second spaced apart reference flats having corresponding first and second parallel reference surfaces forming a cavity therebetween;first and second interferometer devices located on diametrically opposite sides of the cavity;first and second interferogram detectors; and, a) determining first locations of a plurality of holes based on the first intensity frame;', 'b) determining second locations of the plurality of holes based on the second intensity frame;', 'c) comparing the first locations of the plurality of holes determined based on the first intensity frame and the second locations of the plurality of holes determined based on the second intensity frame against first measured locations of the plurality of holes measured utilizing an external measurement device;', 'd) adjusting at least one of: a first optical magnification of a first interferometer channel or a second optical magnification of a second interferometer channel at least partially based on said comparison;', 'e) defining a first ...

LARGE NUMERICAL APERTURE PHASE-SHIFTING DUAL PINHOLE DIFFRACTION INTERFEROMETER AND ITS TEST METHOD

The present invention relates to a large numerical aperture phase-shifting dual pinhole diffraction interferometer and its test method, the diffraction interferometer comprises: reference light passage, test light passage and pinhole substrate; wherein, said pinhole substrate comprises test pinhole and reference pinhole; the diffracted wavefront emitted from the test pinhole would be reflected by the optical component to be tested near the pinhole substrate and converge near the reference pinhole, and said diffracted wavefront comprising surface shape information of optical component to be tested, would be reflected by the pinhole substrate and interference with the diffracted wavefront emitted by reference pinhole, forming interference fringes. The large numerical aperture phase-shifting dual pinhole diffraction interferometer of present invention adopts a dual pinhole substrate and a illumination manner with two converged light paths, enabling the separation of the reference light and test light, to prevent the disturbance between the two light paths, which would induce the change of interferogram status during phase-shifting. By using small field interferogram optical imaging system, the present invention avoids the influence of the test light passage, and achieves a large numerical aperture test in a phase-shifting manner 1. A large numerical aperture phase-shifting dual pinhole diffraction interferometer , comprising:reference light passage, test light passage and pinhole substrate;wherein, there are test pinhole and reference pinhole on said pinhole substrate;via said test light passage, light emitted by laser sources can sequentially approach test beam expanding system and test beam convergent system, then illuminate the test pinhole on the pinhole substrate;via said reference light passage, light emitted by the laser sources can sequentially approach reference beam expanding system, wedge phase-shifting mechanism and reference beam convergent system, then ...

Measuring Topography of Aspheric and Other Non-Flat Surfaces

Generating a composite image of a non-flat surface includes: acquiring, using a microscope, multiple images of different areas of the non-flat surface, where each image includes a region of overlap with at least one adjacent image, the microscope having sufficient resolution to image in three dimensions a microstructure on the non-flat surface having a lateral dimension of 10 microns or less and a height of 10 nm or less; determining, for each of the images, a set of rigid body parameters relating a position and orientation of the test object in the image to a common coordinate system, where the set of rigid body parameters is determined by fitting the resolved microstructure in the overlap region in the image with the corresponding microstructure in the overlap region of the adjacent image; and combining the images based on the sets of rigid body parameters to generate a composite image.

METHOD AND APPARATUS FOR OPTIMIZING THE OPTICAL PERFORMANCE OF INTERFEROMETERS

Method include using an apparatus to measure a first surface field, at a first surface of the apparatus, of an artifact having one or more surface features with known topography. The method includes determining a first focus metric at the first surface based on at least a portion of a first surface profile containing the one or more surface features. Methods include digitally transforming, the first surface field into a second surface field at a second surface of the apparatus, deriving, a second surface profile from the second surface field and computing a second focus metric for the second surface profile, and determining, based on two or more focus metric values, an optimum surface for evaluating the instrument transfer function. Method include determining the instrument transfer function of the apparatus based on at least a portion of the surface profile derived from the surface field of the optimum surface. 1. A method of determining an instrument transfer function of an apparatus , the method comprising:using the apparatus to measure a first surface field, at a first surface of the apparatus, of an artifact having one or more surface features with known topography, the first surface field being a complex electromagnetic field;deriving, using an electronic processor, a first surface profile from the first surface field;identifying, using the electronic processor, the one or more surface features from the first surface profile;determining, using the electronic processor, a first focus metric at the first surface based on at least a portion of the first surface profile containing the surface feature;digitally transforming, using the electronic processor, the first surface field into a second surface field at a second surface of the apparatus, the second surface field being a complex electromagnetic field;deriving, using the electronic processor, a second surface profile from the second surface field and computing a second focus metric for the second surface ...

SPATIAL ACCURACY CORRECTION METHOD AND APPARATUS

A spatial accuracy correction apparatus performs a spatial accuracy correction of a positioner displacing a displacer to a predetermined set of spatial coordinates using a measurable length value measured by an interferometer and a measurable value of the set of spatial coordinates of the displacement body that is measured by the positioner. The measured length value and the measured value for each measurement point are acquired by displacing the displacement body to a plurality of measurement points in order, one or more repeated measurements are conducted for at least one of the plurality of measurement points being measured after conducting measurement of the measured length value and the measured value for each of the plurality of measurement points, and the plurality of points are measured again when a repeat error of the measured length value is equal to or greater than a threshold value. 1. A spatial accuracy correction method having a positioning mechanism displacing a displacement body to a predetermined set of spatial coordinates , the positioning mechanism also having a retroreflector mounted to the displacement body , and a laser interferometer having a reference point and measuring a distance from the reference point to the retroreflector , the method performing spatial accuracy correction of the positioning mechanism using a measured length value measured by the laser interferometer and a measured value for spatial coordinates of the retroreflector measured by the positioning mechanism , the method comprising: displacing the retroreflector to a plurality of measurement points in order, and', conducting at least one or more repeated measurement for at least one of the plurality of measured measurement points, and', 'when an error in the repeated measurement of the measured length value for the measurement point that undergoes the repeated measurement is equal to or greater than a predetermined threshold value, again measuring the plurality of ...

SPATIAL ACCURACY CORRECTION METHOD AND APPARATUS

A method that corrects an error in positioning in a positioning mechanism by using a measurable length value measured by a laser interferometer and a measured value for spatial coordinates measured by the positioning mechanism. The method includes a measurement step in which a retroreflector affixed to a displacer is displaced to a plurality of measurement points, and the measured length value and the measured value at each of the measurement points is acquired; and a parameter calculation step in which a correction parameter is calculated based on the measured value, the measured length value, and the coordinates of a rotation center of the tracking-type laser interferometer. A first correction constant is applied to the measured length value for each measurement line, and a second correction constant different from the first correction constant is applied to the coordinates of the rotation center of the interferometer for each measurement line. 1. A spatial accuracy correction method having a positioning mechanism displacing a displacement body to a predetermined set of spatial coordinates , the positioning mechanism also having a retroreflector mounted to the displacement body , and a laser interferometer having a reference point and measuring a distance from the reference point to the retroreflector , the method performing spatial accuracy correction of the positioning mechanism using a measured length value measured by the laser interferometer and a measured value for spatial coordinates of the retroreflector measured by the positioning mechanism , the method comprising:dividing a plurality of measurement points into a plurality of measurement lines, displacing the displacement body to the plurality of measurement points, and acquiring the measured length value and the measured value at each of the measurement points for each measurement line; and applying a first correction constant to the measured length value for each measurement line; and', 'applying a ...

DEVICE FOR MEASURING THE PARAMETERS OF PHASE ELEMENTS AND OPTICAL FIBER DISPERSION AND A METHOD OF MEASURING THE PARAMETERS OF PHASE ELEMENTS AND OPTICAL FIBER DISPERSION

A device for measuring the parameters of phase elements and dispersion of optical fibers, characterized in that it contains: a light source, serially connected to fiber optic coupler, one of whose arms constitutes a part of the reference arm, and whose second arm constitutes a part of the measurement arm of the device, and a motorized linear stage is mounted on the arm of the device. One of the arms of the device is connected to at least one detector, and at least one collimator is placed in at least of the arms of the device, at least before the phase element. A method of measuring the parameters of the phase element and the dispersion of optical fibers is conducted in two stages, wherein the first stage assumes the calibration of the device and the second stage is the proper measurement. 12111216227172313241425152535411. A device for measuring the parameters , especially thickness or refractive index or dispersion of phase elements , characterized in that the device contains: at least one fiber optic coupler (.) , at least one low-coherence light source (.) , serially connected to at least one input fiber optic coupler (.) , one of whose arms constitutes a part of a reference arm , and whose second arm constitutes a part of a measurement arm of the device , and at least one motorized linear stage () is mounted on at least one arm of the device , and at least one of the arms of the device is connected , either directly , or through an additional output fiber optic coupler (.) , to at least one detector (.; .) , and at least one collimator (.; .; .; .) is placed in at least one of the arms of the device , at least before the measured phase element (.; .; .; .; ).2. (canceled)352. The device according to claim 1 , characterized in that a model phase element (.) selected from among lenses claim 1 , plane-parallel plates claim 1 , optical fibers or other claim 1 , is mounted in the measurement arm.47172. The device according to claim 1 , characterized in that a ...

Reducing Registration Error of Front and Back Wafer Surfaces Utilizing a See-Through Calibration Wafer

A calibration wafer and a method for calibrating an interferometer system are disclosed. The calibration method includes: determining locations of the holes defined in the calibration wafer based on two opposite intensity frame; comparing the locations of the holes against the locations measured utilizing an external measurement device; adjusting a first optical magnification or a second optical magnification at least partially based on the comparison result; defining a distortion map for each of the first and second intensity frames based on the comparison of the locations of the holes; generating an extended distortion map for each of the first and second intensity frames by map fitting the distortion map; and utilizing the extended distortion map for each of the first and second intensity frames to reduce at least one of: a registration error or an optical distortion in a subsequent measurement process. 1. A method for calibrating an interferometer system , the interferometer system including a cavity formed between reference flats in a first interferometer channel and a second interferometer channel , the method comprising:a) placing a calibration wafer in the cavity, the calibration wafer defining a plurality of holes therein;b) acquiring a first intensity frame from the first interferometer channel;c) acquiring a second intensity frame from the second interferometer channel;d) determining locations of the plurality of holes based on the first intensity frame;e) determining locations of the plurality of holes based on the second intensity frame;f) calculating a first distance between a pair of holes of the plurality of holes based on the first intensity frame;g) calculating a second distance between the same pair of holes based on the second intensity frame;h) comparing the first calculated distance and the second calculated distance against a measured distance between the same pair of holes;i) adjusting at least one of: a first optical magnification of the ...

COMPENSATION OPTICAL SYSTEM FOR AN INTERFEROMETRIC MEASURING SYSTEM

A compensation optical unit () for a measurement system () for determining a shape of an optical surface () of a test object () by interferometry generates a measuring wave (), directed at the test object, with a wavefront that is at least partly adapted to a target shape of the optical surface from an input wave (). The unit includes first () and second () optical elements disposed in a beam path of the input wave. The second optical element is a diffractive optical element configured to split the input wave into the measuring wave and a reference wave () following an interaction with the first optical element. At least 20% of a refractive power of the entire compensation optical unit is allotted to the first optical element, and this allotted refractive power has the same sign as the refractive power of the entire compensation optical unit. 1. A compensation optical unit for a measurement system for determining a shape of an optical surface of a test object by interferometry , said compensation optical unit being configured to generate a measuring wave , directed at the test object , with a wavefront that is at least partly adapted to a target shape of the optical surface from an input wave and said compensation optical unit comprising:a first optical element anda second optical element disposed downstream of the first optical element in a beam path of the input wave,wherein a refractive power of the first optical element and a refractive power of the second optical element have mutually same signs,wherein an entirety of the compensation optical unit has a refractive power,wherein the second optical element is a diffractive optical element, which comprises a complex coded phase grating with at least two different phase functions and which is configured to split the input wave into the measuring wave and a reference wave following an interaction of the input wave with the first optical element, andwherein at least 20% of the refractive power of the entire ...

Systems having light source with extended spectrum for semiconductor chip surface topography metrology

Embodiments of systems for classifying interference signals are disclosed. In an example, a system for classifying interference signals includes an interferometer including a light source and a detector, and at least one processor. The interferometer is configured to provide a plurality of interference signals each corresponding to a respective one of a plurality of positions on a surface of a semiconductor chip. A spectrum of the light source is greater than a spectrum of white light. The at least one processor is configured to classify the interference signals into a plurality of categories using a model. Each of the categories corresponds to a region having a same material on the surface of the semiconductor chip.

SYSTEMS AND METHODS FOR SEMICONDUCTOR CHIP SURFACE TOPOGRAPHY METROLOGY

Embodiments of systems and methods for measuring a surface topography of a semiconductor chip are disclosed. In an example, a method for measuring a surface topography of a semiconductor chip is disclosed. A plurality of interference signals each corresponding to a respective one of a plurality of positions on a surface of the semiconductor chip are received by at least one processor. The plurality of interference signals are transformed by the at least one processor into a plurality of spectrum signals each corresponding to the respective one of the positions on the surface of the semiconductor chip. The spectrum signals are classified by the at least one processor into a plurality of categories using a model. Each of the categories corresponds to a region having a same material on the surface of the semiconductor chip. A surface height offset between a surface baseline and at least one of the categories is determined by the at least one processor based, at least in part, on a calibration signal associated with the region corresponding to the at least one of the categories. The surface topography of the semiconductor chip is characterized by the at least one processor based, at least in part, on the surface height offset and the interference signals. 1. A method for measuring a surface topography of a semiconductor chip , comprising:receiving, by at least one processor, a plurality of interference signals each corresponding to a respective one of a plurality of positions on a surface of the semiconductor chip;transforming, by the at least one processor, the plurality of interference signals into a plurality of spectrum signals each corresponding to the respective one of the positions on the surface of the semiconductor chip;classifying, by the at least one processor, the plurality of spectrum signals into a plurality of categories using a model, wherein each of the categories corresponds to a region having a same material on the surface of the semiconductor chip; ...

METHOD FOR MEASURING COMPLEX DEGREE OF COHERENCE OF RANDOM OPTICAL FIELD BY USING MUTUAL INTENSITY-INTENSITY CORRELATION

The invention discloses a method for measuring a complex degree of coherence of a random optical field by using a mutual intensity-intensity correlation, including the steps of: building a test optical path; rotating a quarter-wave plate to enable the fast axis of the quarter-wave plate to be consistent with a polarization direction of reference light, to obtain light intensity distribution information of a first combined light; rotating the quarter-wave plate to enable the slow axis of the quarter-wave plate to be consistent with the polarization direction of the reference light, to obtain light intensity distribution information of a second combined light; blocking the reference light to obtain light intensity distribution information of to-be-tested light; blocking the to-be-tested light to obtain light intensity distribution information of the reference light; and calculating the amplitude and phase of a complex degree of coherence of the to-be-tested light. 1. A method for measuring a complex degree of coherence of a random optical field by using a mutual intensity-intensity correlation , comprising steps of:building a test optical path comprising a quarter-wave plate, a beam splitter, a condensing element, and a light detector, using a laser as reference light, wherein the reference light is modulated by the quarter-wave plate and then enters the beam splitter, and to-be-tested light enters the beam splitter at the same time, the beam splitter combines the modulated reference light and the to-be-tested light to obtain combined light, and the combined light passes through the condensing element to be imaged on the light detector;{'sub': 'S', 'sup': '(1)', 'rotating the quarter-wave plate to enable the fast axis of the quarter-wave plate to be consistent with a polarization direction of the reference light to obtain first combined light, and photographing and recording light intensity distribution information I(r) of the first combined light by using the light ...

METHOD FOR CALIBRATING 3D IMAGING AND SYSTEM FOR 3D IMAGING

A method for calibrating electromagnetic radiation-based three-dimensional imaging includes: obtaining () a calibration imaging result at least partly on the basis of electromagnetic waves received from a calibration artifact, forming () calibration data on the basis of the calibration imaging result and a known thickness profile of the calibration artifact, and correcting (), with the aid of the calibration data, an imaging result obtained at least partly on the basis of electromagnetic waves received from a sample to be imaged. The calibration artifact includes layers, for example Langmuir-Blodgett films, having pre-determined thicknesses and stacked on each other so as to achieve the pre-determined thickness profile of the calibration artifact. A three-dimensional imaging system configured to carry out the method. 122-. (canceled)23. A method for calibrating electromagnetic radiation-based three-dimensional imaging , the method comprising:obtaining a calibration imaging result at least partly on the basis of first electromagnetic waves received from a calibration artifact having a predetermined thickness profile;forming calibration data on the basis of the calibration imaging result and the pre-determined thickness profile of the calibration artifact; andcorrecting, with the aid of the calibration data, an imaging result obtained at least partly on the basis of second electromagnetic waves received from a sample to be imaged,wherein a thickness of the calibration artifact is in a depth direction in which the first electromagnetic waves depart from the calibration artifact, wherein the calibration artifact comprises layers having pre-determined thicknesses and stacked on each other so as to achieve the pre-determined thickness profile of the calibration artifact.24. The method according to claim 23 , wherein the layers of the calibration artifact comprise first layers each being a Langmuir-Blodgett film.25. The method according to claim 24 , wherein each layer ...

OPTICAL PHASE LOCKED LOOPS FOR GENERATING HIGHLY-LINEAR FREQUENCY CHIRPS

Various disclosed embodiments provide illustrative interferometers, optical phase locked loops, laser systems, interferometry methods, and phase locked loop methods. In illustrative embodiments, light from a laser is split into a first arm and a second arm. Light in an arm chosen from the first arm and the second arm is time delayed. The light in the first arm is split into third, fourth, and fifth arms. The light in the second arm is split into sixth, seventh, and eighth arms. Light in the seventh and eighth arms is phase shifted relative to light in the sixth arm. Light in the third, fourth, and fifth arms is combined with light in the sixth arm and phase shifted light in the seventh and eighth arms, respectively. A frequency correction signal for the laser is generated. 14-. (canceled)5. An optical phase locked loop comprising:a first optical splitter configured to split light from a laser into a first arm and a second arm;a delay line configured to time delay light in an arm chosen from the first arm and the second arm;a second optical splitter configured to split the light in the first arm into third, fourth, and fifth arms;a third optical splitter configured to split the light in the second arm into sixth, seventh, and eighth arms;a first phase shifter configured to phase shift light in the seventh arm relative to light in the sixth arm;a second phase shifter configured to phase shift light in the eighth arm relative to light in the sixth arm;a first combiner configured to combine light in the third arm with light in the sixth arm;a second combiner configured to combine light in the fourth arm with phase shifted light in the seventh arm;a third combiner configured to combine light in the fifth arm with phase shifted light in the eighth arm;a first detector configured to detect a first analog electrical signal from light from the first combiner;a second detector configured to detect a second analog electrical signal from light from the second combiner;a third ...

Interferometer

An interferometer includes a first interferometer arm and a second interferometer arm. A first central beam, originating from a central image point of an image, passes through the first interferometer arm. A second central beam, originating from the central image point, passes through the second interferometer arm. The first central beam and the second central beam are superimposed and generate a k=0 interference at a superposition point. A first light beam perpendicular to the first central beam, originating from an image point of the image, passes through the first interferometer arm. A second light beam perpendicular to the second central beam, originating from the image point, passes through the second interferometer arm. The first light beam and the second light beam overlap at the superposition point. At the superposition point, a wave vector component of the first light beam opposes a wave vector component of the second light beam.

CYCLIC ERROR MEASUREMENTS AND CALIBRATION PROCEDURES IN INTERFEROMETERS

An interferometer system, including a heterodyne interferometer and a processing system. The heterodyne interferometer is arranged to provide a reference signal and a measurement signal. The reference signal has a reference phase. The measurement signal has a measurement phase and an amplitude. The processing system is arranged to determine a cyclic error of the heterodyne interferometer based on the reference phase, the measurement phase and the amplitude. 111.-. (canceled)12. A method for calibration of an optical measurement system , the method comprising:measuring, along a measuring direction, a first position or first angular orientation of a target;determining a first cyclic error of the optical measurement system for when the target is at the first position or in the first angular orientation;measuring, along the measuring direction, a second position or second angular orientation of the target;determining a second cyclic error of the optical measurement system for when the target is at the second position or in the second angular orientation, wherein the second position is at a distance from the first position in a direction other than the measuring direction;storing a first corrective value based on the first cyclic error; andstoring a second corrective value based on the second cyclic error.13. The method of claim 12 , comprising:correcting a measurement value of the optical measurement system with the first corrective value for when the target is at or near the first position, andcorrecting a further measurement value of the optical measurement system with the second corrective value for when the target is at or near the second position.1415.-. (canceled)16. The method of claim 13 , comprising correcting a measurement value of the optical measurement system with a part of the first corrective value and a part of the second corrective value for when the target is between the first position and the second position.17. The method of claim 12 , comprising ...

METROLOGY OF MULTI-LAYER STACKS

Techniques for removing interferometry signal phase variations caused by distortion and other effects in a multi-layer stack include: providing an electronic processor sample interferometry data acquired for the stack using a low coherence imaging interferometry system; transforming, by the electronic processor, the sample interferometry data to a frequency domain; identifying a non-linear phase variation from the sample interferometry data in the frequency domain, in which the non-linear phase variation is a result of dispersion introduced into a measurement beam by the test sample; and removing the non-linear phase variation from the sample interferometry data thereby producing compensated interferometry data. 1. A method comprising:providing to an electronic processor sample interferometry data acquired for a test sample using a low coherence imaging interferometry system, wherein the test sample comprises a plurality of layers arranged in a stack;transforming, by the electronic processor, the sample interferometry data to a frequency domain;identifying a non-linear phase variation from the sample interferometry data in the frequency domain, wherein the identified non-linear phase variation is a result of dispersion introduced into a measurement beam by the test sample; andremoving the identified non-linear phase variation from the sample interferometry data in the frequency domain thereby producing compensated interferometry data.2. The method of claim 1 , comprising:directing the measurement beam along a measurement beam path so as to be incident on the test sample;directing a reference beam along a reference beam path so as to contact a reference surface, wherein the measurement beam and the reference beam are derived from light emitted by a common source, the light comprising a plurality of wavelengths, wherein the test sample is at least partially transparent to the plurality of wavelengths;combining the reference beam and the measurement beam to form an ...

CALIBRATION OF AN INTERFEROMETER

In a method for calibrating an interferometer () having a beam path for a measuring beam (), wherein at least one plane () that at least partially reflects the measuring beam () has been introduced into the beam path, and wherein a normal to a first plane () is inclined at a first angle to a measuring beam () incident on the first plane (), the following steps are carried out: interferometric measurement of a first axial spacing of a first point on the first plane () with the measuring beam (), and interferometric measurement of a second axial spacing of a second point on one of the at least one plane () with the measuring beam (), wherein the second point is spaced apart from the first point. 1. An OCT-Scanner comprising an interferometer having a beam path and a test specimen for calibrating the interferometer , wherein the test specimen is arranged in the beam path and has at least one first plane for at least partially reflecting a measuring beam of the interferometer , wherein a normal to the first plane is inclined at a first angle to a beam path incident on the plane.2. The OCT-Scanner according to claim 1 , wherein the first plane is inclinable in a motor-driven manner.3. The OCT-Scanner according to claim 1 , wherein the test specimen comprises a second plane for reflecting the measuring beam claim 1 , said second plane being inclined with respect to the first plane.4. The OCT-Scanner according to claim 1 , comprising a test specimen for calibrating an interferometer for introduction into a beam path of the interferometer claim 1 , having a beam path axis for a measuring beam of the interferometer claim 1 , wherein the test specimen successively comprises at least one first plane and a second plane claim 1 , with which a measuring beam of the interferometer is at least partially reflectable claim 1 , and wherein the first plane is partially transmissible to the measuring beam on both sides claim 1 , and wherein a normal to at least one of the planes is ...

AN ARTIFACT FOR DETERMINING RESOLUTION OF IMAGING BASED ON ELECTROMAGNETIC RADIATION AND/OR MECHANICAL WAVES

An artifact for determining resolution of imaging based on electromagnetic radiation, mechanical waves, or both is presented. The artifact includes a substrate and layers on top of the substrate. The layers include organic material and are stacked on each other in a partially overlapping way so that an edge of a first one of the layers is arranged to intersect with an edge of a second one of the layers. The layers constitute a three-dimensional surface topography where a groove defined by the edges of the first and second ones of the layers is tapering towards a point of intersection between the edges. The resolution is a minimum width of the tapering groove which is revealed by the imaging so that a pre-determined criterion is fulfilled. 125-. (canceled)26. An artifact for determining resolution of imaging based on electromagnetic radiation , mechanical waves , or both electromagnetic radiation and mechanical waves , the artifact comprising:a substrate, andlayers on top of the substrate, the layers comprising organic material,wherein at least two of the layers are stacked on each other in a partially overlapping way so that an edge of a first one of the layers is arranged to intersect with an edge of a second one of the layers, the layers constituting a three-dimensional surface topography where, when the artifact is seen along a direction perpendicular to the layers, a groove defined by the edges of the first and second ones of the layers is tapering towards a point of intersection between the edges.27. An artifact according to claim 26 , wherein each of the layers is a Langmuir-Blodgett film.28. An artifact according to claim 26 , wherein the substrate is made of highly ordered pyrolytic graphite substrate.29. An artifact according to claim 26 , wherein the first one of the layers is on the substrate in contact with substrate claim 26 , the second one of the layers is partially on the substrate in contact with the substrate and partially on the first one of the ...

AN ARTIFACT FOR IMPROVING VERTICAL RESOLUTION OF RADIATION-BASED IMAGING

An artifact for improving the vertical resolution of radiation-based imaging is presented. The artifact has a stepped thickness profile with steps. Adjacent steps are arranged to interact differently with radiation used in the radiation-based imaging. Thus, it is possible to identify which step is, in each imaging situation, vertically closest to the imaging plane related to the radiation-based imaging. Thus, a pre-determined vertical position-value related to the closest one of the steps can be used as a vertical position-value related to a radiation-based imaging result obtained in the imaging situation. 119-. (canceled)20. An artifact for improving vertical resolution of radiation-based imaging , the artifact having a stepped thickness profile with steps , wherein adjacent ones of the steps are arranged to interact differently with radiation used in the radiation-based imaging so that each step is arranged to interact differently with the radiation than any step adjacent to the first-mentioned step.21. An artifact according to claim 20 , wherein surfaces of the adjacent ones of the steps have different reflective properties.22. An artifact according to claim 20 , wherein the adjacent ones of the steps have different radiation-transmission properties.23. An artifact according to claim 20 , wherein surfaces of the adjacent ones of the steps have different scattering properties.24. An artifact according to claim 20 , wherein the artifact comprises substances having wavelength-dependent interacting properties with the radiation used in the radiation-based imaging so that the interacting properties of the adjacent ones of the steps have different wavelength dependencies.25. An artifact according to claim 20 , wherein surfaces of the steps have geometric patterns of areas having different interacting properties with the radiation used in the radiation-based imaging so that the adjacent ones of the steps have different geometric patterns.26. An artifact according to ...

INTERFEROMETER SYSTEM AND USE THEREOF

Interferometer system, including optical means () arranged for directing light along a first interferometer path and (separate) second interferometer path, and for combining the light for allowing interferometry, characterized in that the first interferometer path (PI) is provided with a first light transmitting structure () having a rotational position that is adjustable with respect to an optical axis of the first path. 1. An interferometer system , including optical means arranged for directing light along a first interferometer path and separate second interferometer path , and for combining the light for allowing interferometry ,wherein the first interferometer path is provided with a first light transmitting structure having a rotational position that is adjustable with respect to an optical axis of the first path.2. The interferometer system according to claim 1 , including displacement means for automatically removing the first light transmitting structure from the first path.3. The interferometer system according to claim 1 , wherein the system includes a first translational support structure claim 1 , configured for removably holding the light transmitting structure.4. The interferometer system according to claim 1 , including a drive means for adjusting the rotational position of the first light transmitting structure claim 1 , the drive means for example including a rotational support structure for rotationally holding the light transmitting structure.5. The interferometer system according to claim 3 , wherein the first translational support structure is integrated with a rotational support structure of the drive means.6. The interferometer system according to claim 3 , wherein the first translational support structure is configured for removably holding the light transmitting structure by removably holding the respective rotational support structure of the drive means.7. The interferometer system according to claim 3 , wherein first translational ...

METHOD OF CALIBRATING INTERFEROMETER AND INTERFEROMETER USING THE SAME

A calibration method capable of improving distortion of a waveform of a point-spread-function without constantly executing feedback control to a wavelength-swept light source is provided. According to the present invention, an interference signal (S(t)) is generated by varying voltage (V) to be applied to a light source () within one period T, the interference signal (S(t)) is sampled at equal time intervals on a time axis, the point-spread-function is obtained through Fourier transform by multiplying by a first window function, and a complex analysis signal including frequency information of light is obtained through inverse Fourier transform by multiplying the point-spread-function by a second window function. After a variation in a frequency of the light relative to a time within one period is obtained at equal time intervals by unwrapping phase information of the complex analysis signal, a correspondence relationship between the variation in the frequency of the light within one period, which is sampled at the equal time intervals, and a variation in voltage within one period, which is sampled at the equal time intervals, is obtained. Correspondence voltage (CV) is obtained by subdividing the variation in the frequency of the light within one period into equal intervals based on the correspondence relationship, and the voltage (V) to be applied to the light source () is substituted into the correspondence voltage (CV). 1. A method of calibrating an interferometer , comprising:a first step of generating a spectrum interference signal through sweep of a wavelength of light of a wavelength-swept light source by varying, relative to a time, voltage to be applied to the wavelength-swept light source within one period;a second step of obtaining a point-spread-function by sampling the spectrum interference signal at equal time intervals on a time axis, and Fourier transforming the sampled spectrum interference signal by multiplying by a first window function;a third ...

METHOD AND APPARATUS FOR OPTIMIZING THE OPTICAL PERFORMANCE OF INTERFEROMETERS

A method for measuring a property of a test object with an interferometer includes: a) providing calibration information relating a focus setting for the interferometer to a position of the test object relative to a reference surface of the interferometer; b) determining the position of the test object relative to the reference surface; and c) using the interferometer to collect interferometric images of the test object for use in measuring the property of the test object. 1. A method for measuring a property of a test object with an interferometer , the method comprising:a. providing calibration information relating a focus setting for the interferometer to a position of the test object relative to a reference surface of the interferometer;b. determining the position of the test object relative to the reference surface; andc. using the interferometer to collect interferometric images of the test object for use in measuring the property of the test object;d. wherein the method further comprises using one or more electronic processors to mathematically propagate at least one wavefront derived from the interferometric images based on the calibration information and the determined position of the test object relative to the reference surface to improve a degree of focus of the wavefront derived from the interferometric images.2. The method of claim 1 , wherein the interferometer comprises a ruled stage for supporting the test object and wherein determining the position of the test object relative to the reference surface comprises manually or automatically reading the ruled stage.3. The method of claim 1 , wherein the interferometer comprises a light source having a variable wavelength claim 1 , wherein the interferometric images are collected while adjusting the wavelength of the light source claim 1 , and wherein the position of the test object relative to the reference is determined based on the interferometric images collected while adjusting the wavelength of the ...

METHOD AND APPARATUS FOR MOTION COMPENSATION IN INTERFEROMETRIC SENSING SYSTEMS

Interferometric measurement signals are detected by a single optical interferometric interrogator for a length of a sensing light guide and an interferometric measurement data set corresponding to the interferometric measurement signals is generated. The interferometric measurement data set is transformed into a spectral domain to produce a transformed interferometric measurement data set. The transformed interferometric measurement data set is compared to a baseline interferometric data set to identify a time-varying signal corresponding to a time-varying disturbance. The baseline interferometric data set is representative of the sensing light guide not being subjected to the time-varying disturbance. A compensating signal is determined from the time-varying signal and used to compensate at least a portion of the interferometric measurement data set for the time-varying disturbance as part of producing a measurement of the parameter. 1. An optical interrogation system for measuring a parameter of a sensing light guide , the optical interrogation system comprising:an optical interferometric interrogator configured to couple to the sensing light guide;optical detection circuitry configured to detect interferometric measurement signals for a length of the sensing light guide, wherein the interferometric measurement signals are from the optical interferometric interrogator and not from any other optical interferometric interrogator; and receive the interferometric measurement signals from the optical detection circuitry;', 'generate an interferometric measurement data set corresponding to the interferometric measurement signals;', 'transform the interferometric measurement data set into a spectral domain to produce a transformed interferometric measurement data set;', 'compare the transformed interferometric measurement data set to a baseline interferometric data set to identify a time-varying signal corresponding to a time-varying disturbance, the baseline ...

Manual calibration of imaging system

The invention generally relates to methods for manually calibrating imaging systems such as optical coherence tomography systems. In certain aspects, an imaging system displays an image showing a target and a reference item. A user looks at the image and indicates a point within the image near the reference item. A processor detects an actual location of the reference item within an area around the indicated point. The processor can use an expected location of the reference item with the detected actual location to calculate a calibration value and provide a calibrated image. In this way, a user can identify the actual location of the reference point and a processing algorithm can give precision to the actual location.

METHOD AND SYSTEM FOR DETERMINING THE LOCAL POSITION OF AT LEAST ONE OPTICAL ELEMENT IN A MACHINE FOR LASER PROCESSING OF A MATERIAL, USING LOW-COHERENCE OPTICAL INTERFEROMETRY TECHNIQUES

A method for determining local position of an optical element associated with an optical path for transporting a laser beam in a working head of a machine for laser processing a material, includes generating a measurement beam of low coherence optical radiation traveling a measurement optical path, leading the measurement beam towards the optical element and the reflected or diffused measurement beam towards an optical interferometric sensor arrangement, generating a reference beam of low coherence optical radiation traveling a reference optical path and leading the reference beam towards the interferometric optical sensor arrangement, superimposing the measurement and reference beams on a common region of incidence, detecting a position of a pattern of interference fringes between the measurement and reference beams, and determining a difference in optical length between the measurement and reference optical paths as a function of the position of the interference pattern along an illumination axis, or of the frequency of the interference pattern in the frequency domain. 1. A method for determining a local position of at least one optical element associated with an optical transport path for a laser beam in a working head of a machine for laser processing of a material , the method comprising:generating a respective measurement beam of low coherence optical radiation, leading said measurement beam towards said at least one optical element, and leading the measurement beam reflected or diffused by at least one back-reflective surface of said at least one optical element, on which said measurement beam impinges with at least a partial back-reflection, towards an optical interferometric sensor arrangement, wherein the measurement beam travels a measurement optical path from a respective source to said optical interferometric sensor arrangement including a first section between said source and said at least one back-reflective surface of said at least one optical ...

执行光学相干层析术中的基于偏振的正交解调的设备、方法和存储介质

设备、方法和存储介质，其可向样品130提供至少一个第一电磁辐射并且向参考提供至少一个第二电磁辐射，使得第一和/或第二电磁辐射具有随时间变化的谱。此外，第一辐射所关联的至少一个第三辐射405的第一偏振分量可与第二辐射所关联的至少一个第四辐射400的第二偏振分量彼此相组合。第一和第二偏振可被特定控制为彼此至少近似正交。设备和方法用于扫掠源傅立叶域光学相干层析术的正交检测。

Scanning white-light interferometry system for characterization of patterned semiconductor features

A white light interferometric metrology device operates in the image plane and objective pupil plane. The interferometric metrology device extracts the electric field with complex parameters and that is a function of azimuth angle, angle of incidence and wavelength from interferometric data obtained from the pupil plane. Characteristics of the sample are determined using the electric field based on an electric field model of the azimuth angle, the angle of incidence and the wavelength that is specific for a zero diffraction order. A center of the pupil in the pupil plane may be determined based on a Fourier transform of the interferometric data at each new measurement and used to convert each pixel from the camera imaging the objective pupil plane into a unique set of angle of incidence and azimuth angle of light incident on the sample.

Systems and methods for phase measurements

Preferred embodiments of the present invention are directed to systems for phase measurement which address the problem of phase noise using combinations of a number of strategies including, but not limited to, common-path interferometry, phase referencing, active stabilization and differential measurement. Embodiment are directed to optical devices for imaging small biological objects with light. These embodiments can be applied to the fields of, for example, cellular physiology and neuroscience. These preferred embodiments are based on principles of phase measurements and imaging technologies. The scientific motivation for using phase measurements and imaging technologies is derived from, for example, cellular biology at the sub-micron level which can include, without limitation, imaging origins of dysplasia, cellular communication, neuronal transmission and implementation of the genetic code. The structure and dynamics of sub-cellular constituents cannot be currently studied in their native state using the existing methods and technologies including, for example, x-ray and neutron scattering. In contrast, light based techniques with nanometer resolution enable the cellular machinery to be studied in its native state. Thus, preferred embodiments of the present invention include systems based on principles of interferometry and/or phase measurements and are used to study cellular physiology. These systems include principles of low coherence interferometry (LCI) using optical interferometers to measure phase, or light scattering spectroscopy (LSS) wherein interference within the cellular components themselves is used, or in the alternative the principles of LCI and LSS can be combined to result in systems of the present invention.

Multiple-angle multiple-wavelength interferometer using high-NA imaging and spectral analysis

A method is disclosed including: generating a scanning interferometry signal at each of multiple wavelengths for each of at least one location on a test object; obtaining the scanning interferometry signals at each of the multiple wavelengths for each of at least one location on the test object; analyzing the scanning interferometry signals to determine information about the test object; and outputting the information about the test object. Each scanning interferometry signal corresponds to interference between test light and reference light as an optical path length difference between the test and reference light is varied. The test and reference light are derived from a common source, and the test light emerges from the test object over a range of angles corresponding to a numerical aperture of greater than 0.7.

Interferometry method for ellipsometry, reflectometry, and scatterometry measurements, including characterization of thin film structures

A method including: imaging test light emerging from a test object over a range of angles to interfere with reference light on a detector, wherein the test and reference light are derived from a common source; for each of the angles, simultaneously varying an optical path length difference from the source to the detector between interfering portions of the test and reference light at a rate that depends on the angle at which the test light emerges from the test object; and determining an angle-dependence of an optical property of the test object based on the interference between the test and reference light as the optical path length difference is varied for each of the angles.

The method and device of motion compensation in interference-type sensor-based system

光学解调系统例如基于OFDR的系统测量经受时变干扰的传感光波导的折射率的局部变化。为一定长度的传感光波导检测的干涉测量信号被变换到谱域。从变换的干涉测量数据集确定时变信号。从时变信号确定补偿信号，该补偿信号用于为干涉测量数据集补偿时变干扰。通过使用求平均和应变补偿实现进一步的鲁棒性。该补偿技术可以沿光波导的长度被应用。

Interferometer and measurement method adopting said interferometer

提供了高精度快速初步与主要测量的干涉仪和方法。激光与白光连续导入同一个干涉仪室。激光从激光源导入,利用CCD与个人机检测以基准镜作为基准的干涉条纹。把干涉条纹置成预置值,调节工件位置。然后导入白光,移动直角移动架,检测以基准镜作为基准的干涉条纹,执行工件的初步测量。再导入激光,检测以基准镜作为基准的干涉条纹,作工件的主要测量。

Systems and methods for phase measurements

Preferred embodiments of the present invention are directed to systems for phase measurement which address the problem of phase noise using combinations of a number of strategies including, but not limited to, common-path interferometry, phase referencing, active stabilization and differential measurement. Embodiment are directed to optical devices for imaging small biological objects with light. These embodiments can be applied to the fields of, for example, cellular physiology and neuroscience. These preferred embodiments are based on principles of phase measurements and imaging technologies. The scientific motivation for using phase measurements and imaging technologies is derived from, for example, cellular biology at the sub-micron level which can include, without limitation, imaging origins of dysplasia, cellular communication, neuronal transmission and implementation of the genetic code. The structure and dynamics of sub-cellular constituents cannot be currently studied in their native state using the existing methods and technologies including, for example, x-ray and neutron scattering. In contrast, light based techniques with nanometer resolution enable the cellular machinery to be studied in its native state. Thus, preferred embodiments of the present invention include systems based on principles of interferometry and/or phase measurements and are used to study cellular physiology. These systems include principles of low coherence interferometry (LCI) using optical interferometers to measure phase, or light scattering spectroscopy (LSS) wherein interference within the cellular components themselves is used, or in the alternative the principles of LCI and LSS can be combined to result in systems of the present invention.

A kind of grating interferometer alignment error real-time correction method

本发明公开了一种光栅干涉仪对准误差实时校正方法，包括光栅干涉仪位移测量光路、位姿偏转检测光路、光电检测模块、干涉仪信号处理与误差补偿模块。光栅干涉仪位移测量光路主要由激光光源、光栅、非偏振分光镜、偏振分光镜、四分之一波片组成；位姿偏转检测光路主要由半透半反镜和聚焦透镜组成；干涉仪信号处理与误差补偿处理光栅干涉仪信号位移解调与光栅测量误差补偿。本发明利用对称光路以及四象限探测器来测量光学读数头相对于光栅尺空间位姿绕x轴、y轴和z轴偏转量，通过误差补偿模型对位移测值实时进行实时校正，最终达到提高光栅干涉仪测量精度的目的，测量简单，误差小。

Thin films and surface topography measurement using reduced library

The properties of a surface of an object in presence of thin transparent films are determined by generating a library of model signals and processing a measurement signal via searching the library to evaluate films properties and topography. The library may be reduced with principal component analysis to enhance computation speed. Computation enhancement may also be achieved by removal of the height contributions from the signal leaving only the film contribution in the signal. The film measurement signal is compared to a library of film signals to determine the film parameters of the sample. The library of film signals is produced by processing each full signal in a library to similarly remove the height contributions leaving only the film contributions. Additionally, a post-analysis process may be applied to properly evaluate local topography.

Method and an apparatus for measuring a deviation of an optical test surface from a target shape

A method of measuring a deviation of an optical test surface from a target shape is provided. The method includes directing an incoming beam of electromagnetic radiation onto the test surface to generate a measuring beam that has interacted with the test surface, causing the ray that has interacted with the test surface to pass through an interferometer on a deviated path, performing an interferometric measurement by superimposing a reference beam with the measuring beam to determine a wave front deviation of the measuring beam from the reference beam, determining a retrace error in the wave front deviation, and correcting the measured wave front deviation by eliminating the retrace error therefrom. The differences in aberrations accumulated by the ray having traveled on the deviated path from fictitious aberrations that would have been accumulated by a ray that had traveled on an undeviated path cause the retrace error.

A kind of phase demodulating device and demodulation method for inhibiting light-intensity variation noise

本发明公开了一种抑制光强波动噪声的相位解调装置及解调方法。包括光纤干涉仪和数字解调装置；本发明对传统的相位生成载波算法进行改进，将被测相位的基频分量与倍频分量做乘积，同时将基频分量的微分值与倍频分量的微分值做乘积，将这两个乘积相除从而去掉光强抖动引起的噪声，再通过积分的方法求解被测相位；同时，本发明将降噪解调算法集成于FPGA与DSP大规模高速信号处理器中，根据FPGA并行处理能力强以及DSP浮点运算性能优越的特点，分别将微分以及相位求解部分实现于两个处理器内，保证实时性；本发明有效抑制了光强波动引起的噪声，提高了长期稳定性，可广泛用于高精度光纤测量和光纤传感等领域。

Method and device for heterodyne interferometer error correction

본 발명은 헤테로다인 간섭계의 주기적 오차를 정정하는 방법에 관한 것이다. 이를 위해서는 두 부분구간으로 나뉜 고정불변의 캘리브레이션 구간에 대하여 캘리브레이션 측정을 반복하는데, 한 부분구간은 간섭계로 측정하며, 다른 부분구간은 측정구간을 따라 주기적 오차를 보이지 않는 거리측정 추가 시스템으로 측정한다. 캘리브레이션 측정을 할 때마다 측정에 앞서 간섭계에 의해 측정되는 부분구간이 조금씩 변경된다. 그러면 제2 부분구간도 반대방향으로 변경된다. 한 부분구간의 거리 변경의 합은 적어도 한 측정광 파장 크기의 간섭계 광로 길이 변화와 일치해야 한다. 고정불변의 캘리브레이션 구간에 대한 상이한 캘리브레이션 측정결과들에서 주기적 오차 부분이 분리되고, 임의의 간섭계 측정을 정정하기 위하여 파장에 따른 오차 곡선이 결정된다. The present invention relates to a method for correcting a periodic error of a heterodyne interferometer. To this end, the calibration measurement is repeated for a fixed-invariant calibration section divided into two subsections, one with the interferometer and the other with the distance measurement additional system, which shows no periodic error along the measurement interval. Each time a calibration measurement is made, the subsection measured by the interferometer changes slightly before the measurement. Then, the second partial section is also changed in the opposite direction. The sum of the distance change of one subdivision shall coincide with the change of the interferometer optical path length of at least one measurement light wavelength. The periodic error portion is separated from the different calibration measurement results for the fixed invariant calibration interval, and the error curve according to the wavelength is determined to correct any interferometer measurement.

System, method, apparatus and computer-accessible medium for providing polarization mode dispersion compensation in optical coherence tomography

少なくとも１つのサンプルに関する情報を生成するための例示的なシステム、装置、方法およびコンピュータアクセス可能媒体が提供され得る。例えば、サンプルに提供される少なくとも１つの第１の放射線および第１の放射線に関連するサンプルから提供される少なくとも１つの第２の放射線に基づいて第１のデータを受信することが可能である。サンプルに到達する前に第１の放射線上で誘導される第１の光学的効果、およびサンプルから出て行った後に第２の放射線上で誘導される第２の光学的効果の影響を減少させることによって第２のデータを生成することも可能である。 【選択図】図１

Interferometer i.e. spectral interferometer, for layer thickness measurement, has light cable arranged in optical path for complete controlling of wave length- and/or polarization-dependent effects on thickness measurement result

The interferometer (10) has a light source (12) e.g. LED, producing measuring light, and a spectrometer (14) provided with a detector (44) for detecting spectral light intensity distribution. The spectrometer is coupled to the light source by an optical path. A beam-splitting device provides detection light at a diffraction grating (42) arranged at the spectrometer. A light cable (24) is arranged in the optical path for complete controlling of wave length- and/or polarization-dependent effects on a thickness measurement result determined by the spectrometer. An independent claim is also included for a method for operating an interferometer.

Distance measuring device and method for measuring distances

A device for measuring a distance to an object comprises a beam splitter for splitting broadband coherent light emitted by a light source in measuring light which is guided through an object arm to the object to be measured and in reference light which is guided to a reference arm. The object arm includes a focusing optics with a focus movable along an optical axis of the object arm. The focusing optics comprises a movable optical element and is configured such that a movement of the movable optical element along the optical axis causes a higher movement of the focus of the focusing optics along the optical axis. The movable optical element of the focusing optics is coupled to the reference arm such that the optical path length of the reference arm can be tracked synchronously with and dependent on the movement of the focus of the focusing optics.

Interferometry method and system including spectral decomposition

In general, in one aspect, the disclosure features a method that includes directing measurement light to reflect from a measurement surface and combining the reflected measurement light with reference light, where the measurement light and reference light are derived from a common source, and there is a non-zero optical path length difference between the measurement light and reference light that is greater than a coherence length of the measurement light. The method further includes spectrally dispersing the combined light onto a multi-element detector to detect a spatially-varying intensity pattern, determining spatial information about the measurement surface based on the spatially-varying intensity pattern, and outputting the spatial information.

Refractive prescription using optical coherence tomography

An optical coherence tomography apparatus and method for measuring refractive power of the human cornea is disclosed. The apparatus collects both the specularly reflected light from the anterior surface of the cornea and diffusely reflected light from the interior of the cornea. The combined refractive power of both surfaces of the cornea is determined.

Interferometer and method for operating an interferometer

Spektrales Interferometer zur Schichtdickenmessung mit einer Lichtquelle (12) zur Bereitstellung von Messlicht, von dem an wenigstens zwei optischen Grenzflächen eines Messobjekts wenigstens zwei Detektionslicht bildende Anteile teilweise zurückreflektiert werden, die wellenlängenabhängig miteinander interferieren, sowie mit einem Spektrometer (14), das zur Ermittlung einer spektralen Lichtintensitätsverteilung, die durch die Interferenz der beiden Anteile festgelegt wird, mit einer Detektoranordnung (44) ausgerüstet ist, die über einen optischen Pfad mit der Lichtquelle (12) gekoppelt ist, wobei der optische Pfad eine Faseranordnung (18, 20, 24; 18, 20, 124; 18, 20, 224) zur Lichtübertragung, einen mit der Faseranordnung (18, 20, 24; 18, 20, 124; 18, 20, 224) verbundenen Messkopf (32; 132) mit einem optischen System (34; 134) zur Auskopplung des Messlichts aus der Faseranordnung (18, 20, 24; 18, 20, 124; 18, 20, 224) und zur Einkopplung des Detektionslichts in die Faseranordnung (18, 20, 24; 18, 20, 124; 18, 20, 224) und eine der Faseranordnung (18, 20,... Spectral interferometer for measuring layer thickness with a light source (12) for providing measurement light from which at least two optical boundary surfaces of a measurement object at least two detection light forming portions are partially reflected back, which interfere with one another wavelength dependent, as well as with a spectrometer (14) for determining a spectral light intensity distribution determined by the interference of the two components is equipped with a detector arrangement (44) which is coupled via an optical path to the light source (12), the optical path comprising a fiber arrangement (18, 20, 24, 18 , 20, 124, 18, 20, 224) for transmitting light, a measuring head (32, 132) connected to the fiber arrangement (18, 20, 24, 18, 20, 124, 18, 20, 224) having an optical system (34 134) for coupling the measuring light out of the fiber arrangement (18, 20, 24, 18, 20, 124, 18, 20, 224) and for ...

Surface shape measuring apparatus, exposure apparatus, and device manufacturing method

Method of manufacturing an optical system

A method of manufacturing a projection optical system ( 37 ) for projecting a pattern from a reticle to a photosensitive substrate, comprising a surface-shape-measuring step wherein the shape of an optical test surface ( 38 ) of an optical element ( 36 ) which is a component in the projection optical system is measured by causing interference between light from the optical surface ( 38 ) and light from an aspheric reference surface ( 70 ) while the optical test surface ( 38 ) and said reference surface ( 70 ) are held in integral fashion in close mutual proximity. A wavefront-aberration-measuring step is included, wherein the optical element is assembled in the projection optical system and the wavefront aberration of the projection optical system is measured. A surface correction calculation step is also included wherein the amount by which the shape of the optical test surface should be corrected is calculated based on wavefront aberration data obtained at the wavefront-aberration-measuring step and surface shape data obtained from the surface-shape-measuring step. The method also includes a surface shape correction step wherein the shape of the optical test surface is corrected based on calculation performed at the surface correction calculation step. Surface shape measuring interferometer systems and wavefront-aberration-measuring interferometer systems ( 22 J- 22 Q) used in performing the manufacturing method are also disclosed.

Interferometric apparatus and methods for measuring surface topography of a test surface

Apparatus and methods are disclosed for measuring the surface topography of a test surface, such as a spherical or aspherical surface of a refractive or reflective optical element. The test surface is measured by detecting the state of interference fringes generated by interference of a reference light beam and a measurement light beam that interacts (e.g., reflects from) the test surface. The reference and measurement beams are produced by a point light source having a reflective surface. The point light source is disposed between a source of input light and the test surface. The measurement beam (after interacting with the test surface) and the reference beam are caused to interfere with each other to produce a first interference-fringe state. The distance between the point light source and the test surface can be changed between production of the first interference-fringe state and production of a second interference-fringe state. The profile of the test surface is determined by analyzing the resulting interference fringes. A null element can be used to convert a spherical wavefront of the measurement beam into an aspherical wavefront corresponding to the aspherical test surface, or to convert an aspherical wavefront generated by reflection of a spherical wavefront from an aspherical test surface into a spherical or planar wavefront.

Polarization independent optical coherence-domain reflectometry

An optical coherence-domain reflectometry system provides an interferometer driven by a broadband incoherent light source with the device under test connected to one arm of the interferometer and a movable scanning mirror in the other arm providing a reference signal. The mirror moves at a controlled velocity to produce a Doppler shift in the reference signal frequency. The reference signal arm also includes a piezoelectric transducer which modulates the phase of the reference signal at a given frequency, causing a further shift in the reference signal frequency. The interference signal is detected and measured by a polarization diversity receiver. A linear polarizer in the reference signal arm is adjusted to produce equal reference signal powers in each arm of the polarization diversity receiver in the absence of a reflection signal from the test arm. The measured reflectometry signal is substantially independent of the state of polarization of the reflected signal from the device under test.

Method and apparatus for performing optical measurements using a rapidly frequency-tuned laser

An optical system, in one embodiment including an external-cavity frequency-tuned laser having a tunable longitudinal cavity mode and a center tunable wavelength. The external-cavity frequency-tuned laser includes an optical cavity, an optical gain medium positioned within the optical cavity, and a rapid tuning wavelength selecting device positioned to receive light from the optical gain medium and adapted to return selected wavelengths of light to the optical gain medium. The external-cavity frequency-tuned laser is substantially continuously tunable and the tunable wavelength selecting device tunes the center wavelength of the external-cavity frequency-tuned laser at the same rate as the longitudinal cavity mode of the external-cavity frequency-tuned laser is tuned. In another embodiment the optical system includes an interferometer in optical communication with the external-cavity frequency-tuned laser. The interferometer is adapted to project a portion of light from the external-cavity frequency-tuned laser onto a sample, to receive light altered by the sample, and to combine light reflected from the sample and the light from the external-cavity frequency-tuned laser. A detector positioned to receive the combined light from the interferometer and to generate a signal in response thereto. A processing unit in communication with the detector performs digital signal processing to extract spatial information related to the sample in response to the signal from the detector.

Method and apparatus for calibrating a polarization independent optical coherence domain reflectometer

An optical coherence-domain reflectometry system provides an interferometer driven by a broadband incoherent light source with the device under test connected to one arm of the interferometer and a movable scanning mirror in the other arm providing a reference signal. The mirror moves at a controlled velocity to produce a Doppler shift in the reference signal frequency. The interference signal is detected and measured by a receiver. In the case where the receiver is a polarization diversity receiver, an intensity modulator and a polarization controller are incorporated into the reflectometer for use in calibrating the receiver. Calibration is also provided for a single photodetector receiver.

Image enhancement in optical coherence tomography using deconvolution

The present invention provides an improved optical coherence tomography system and involves estimating the impulse response (which is indicative of the actual reflecting and scattering sites within a tissue sample) from the output interferometric signal of an interferometer according to the following steps: (a) acquiring auto-correlation data from the interferometer system; (b) acquiring cross-correlation data from the interferometer system having the biological tissue sample in the sample arm; and (c) processing the auto-correlation data and the cross correlation data to produce an optical impulse response of the tissue. The impulse response may be obtained from the cross-correlation and auto-correlation data by: (d) obtaining an auto-power spectrum from the auto-correlation data by performing a Fourier transform on the auto-correlation data; (e) obtaining a cross-power spectrum from the cross-correlation data by performing a Fourier transform on the cross-correlation data; (f) obtaining a transfer function of the LSI system by taking a ratio of the cross-power spectrum to the auto-power spectrum; and (g) obtaining the optical impulse response of the LSI system by performing an inverse-Fourier transform on the transfer function. Preferably, coherent demodulation is used in combination with the above deconvolution technique to resolve closely-spaced reflecting sites in the sample. By utilizing both the magnitude and phase data of the demodulated interferometric signals, the OCT system of the present invention is able to distinguish between closely spaced reflecting sites within the sample.

Depth-resolved spectroscopic optical coherence tomography

A method is described for determining depth-resolved backscatter characteristics of scatterers within a sample, comprising the steps of: acquiring a plurality of sets of cross-correlation interferogram data using an interferometer having a sample arm with the sample in the sample arm, wherein the sample includes a distribution of scatterers therein, and wherein the acquiring step includes the step of altering the distribution of scatterers within the sample with respect to the sample arm for substantially each acquisition; and averaging, in the Fourier domain, the cross-correlation interferogram data, thereby revealing backscattering characteristics of the scatterers within the sample.

RETRO-REFLECTED LIGHT MEASUREMENT BY AN OPTICAL INSTRUMENT

Un procédé pour mesurer une quantité de lumière qui est rétro-réfléchie par un instrument d’optique (1) comprend d’utiliser l’instrument d’optique en tant que réflecteur pour un interféromètre (10). Des variations sont appliquées à une position instantanée de l’instrument d’optique pour provoquer des variations d’un éclairement d’interférence. Un rotateur de Faraday (17) est disposé devant l’instrument d’optique pour varier une direction de polarisation linéaire d’illumination, et/ou une direction de polarisation linéaire d’analyse, afin de permettre d’analyser une dépendance de la quantité de lumière rétro-réfléchie en fonction des directions de polarisation linéaire d’illumination et/ou d’analyse. Une détection synchrone peut en outre être utilisée pour mesurer précisément des quantités de lumière rétro-réfléchie qui peuvent être très faibles. Figure d’abrégé : Figure 1 A method for measuring an amount of light that is retro-reflected by an optical instrument (1) includes using the optical instrument as a reflector for an interferometer (10). Variations are applied to an instantaneous position of the optical instrument to cause variations in interference illumination. A Faraday rotator (17) is disposed in front of the optical instrument to vary a direction of linear polarization of illumination, and / or a direction of linear polarization of analysis, to allow analysis of a quantity dependence. of retro-reflected light as a function of the directions of linear polarization of illumination and / or analysis. Synchronous detection can further be used to accurately measure amounts of back-reflected light which may be very small. Abstract figure: Figure 1

Optical phase measurement method and system

패턴화된 샘플의 파라미터를 측정하는데 사용하기 위한 측정 시스템이 제시된다. 상기 시스템은, 광역 광 소스, 간섭 시스템으로서 구성된 광학 시스템, 검출 유닛 및 제어 유닛을 포함하되, 상기 간섭 시스템은 기준 반사기를 포함하는 기준 암 및 샘플 암을 가진 조명 및 검출 채널을 형성하고, 샘플 암과 기준 암 사이의 광학 경로 차이를 유도하도록 구성되며, 상기 검출 유닛은 상기 반사기로부터 반사된 광선 및 샘플의 지지부로부터 전파되는 광선에 의해 형성된 결합된 광선을 검출하고, 적어도 두 개의 스펙트럴 간섭 특징에 의해 형성된 스펙트럴 간섭 패턴을 나타내는 측정된 데이터를 생성하도록 구성되고 작동되며, 상기 제어 유닛은 샘플 내의 패턴의 하나 이상의 파라미터를 결정하기 위해, 측정된 데이터를 수신하고, 모델-기반의 프로세싱을 스펙트럴 간섭 패턴에 적용하도록 구성되고 작동된다.

Cuvette for Ophthalmic Lens

변형된 마흐젠더(MZ) 간섭계는 다중 렌즈들을 유지할 수 있는 회전가능한 캐러셀을 구비한 큐벳에 렌즈를 설치함으로써 안과용 렌즈의 투과된 비구형 파면을 분석하기 위하여 사용된다. 신선한 온도 제어된 식염수 용액은 렌즈 주위에서 순환하고, 큐벳은 간섭계 구성의 수직 시험 아암에 위치한다. 역광선 추적(reverse raytracing)은 렌즈 바로 뒤에서 간섭계의 검출기로 결상될 때 파면 안으로 유도되는 수차를 제거하는데 사용될 수 있다. 간섭계, 캐러셀, 큐벳, 안과용 렌즈, 식염수 용액, 역광선 추적 A modified Machzendor (MZ) interferometer is used to analyze the transmitted non-spherical wavefront of the ophthalmic lens by placing the lens in a cuvette with a rotatable carousel capable of holding multiple lenses. Fresh temperature-controlled saline solution circulates around the lens, and the cuvette is placed in the vertical test arm of the interferometer configuration. Reverse raytracing can be used to eliminate aberrations introduced into the wavefront when imaged with the detector of the interferometer directly behind the lens. Interferometer, carousel, cuvette, ophthalmic lens, saline solution, backlight tracking

High-speed in-situ acquisition of aspheric Fizeau

球面および波面の正確な測定で不確定性を低減する追加可能な較正を用いる方法である。透過球面は、干渉計に取り付けられ、この透過球面から現れる波面が案内面上に取り付けられた実質的に「完璧な」球面のように機能させるように所定の態様で移動およびサンプリングされる光学球面と透過球面とを比較することによって較正される。透過非球面は、干渉計に取り付けられ透過非球面から生じる波面が案内面に取り付けられた較正された球面アーティファクトとこの透過非球面とを比較することによって較正される。干渉計によって較正された非球面波面は、決定するために案内面に取り付けられた非球面アーティファクトを測定するために用いられる。透過非球面から生じる波面の較正は品質改善および保証の基礎として用いられる履歴データを提供するために周期的に更新される。

A kind of efficiently accurate calibration method of the laser interferometer light path based on PSD

本发明公开了一种基于PSD的激光干涉仪光路高效精确校准方法，首先建立系统光路，然后粗调整激光干涉仪光路，最后根据PSD二维光敏位置传感器获取各校准点的坐标值并计算测量光相对于参考反射光的偏移量，并根据偏移量对激光干涉仪光路进行精确调整。本发明通过PSD二维光敏位置传感器中测量的坐标实现自动校准激光干涉仪光路，本发明利用PSD二维光敏位置传感器获取校准光束的偏移量，从而间接的得到测量光的偏移量，可以实现自动调节光路，从而实现高精度的光路校准，提高了校准的效率和精度，具有较好的实用性。

Apparatus and method for measuring characteristics of surface features

An apparatus is disclosed which includes an interferometry system configured to operate in a first mode to produce a first set of multiple interferometry signals corresponding to different illumination angles of a test object by test light and in a second mode produce a second set of multiple interferometry signals corresponding to different surface locations of a test object. An electronic processor coupled to the interferometry system is configured to receive the first set of interferometry signals and programmed to compare information derivable from the first set of multiple interferometry signals to information corresponding to multiple models of the test object to determine information related to one or features of the test object, and output the information. In some embodiments, the features include an under-resolved feature.

Apparatus, methods and storage medium for performing polarization-based quadrature demodulation in optical coherence tomography

Apparatus, method and storage medium which can provide at least one first electro-magnetic radiation to a sample and at least one second electromagnetic radiation to a reference, such that the first and/or second electromagnetic radiations have a spectrum which changes over time. In addition, a first polarization component of at least one third radiation associated with the first radiation can be combined with a second polarization component of at least one fourth radiation associated with the second radiation with one another. The first and second polarizations may be specifically controlled to be at least approximately orthogonal to one another.

Measurement method and measurement apparatus

The present invention provides a measurement apparatus that illuminates a surface to be tested having an aspheric surface using light beams that form spherical waves to measure a figure of the surface to be tested, including a detection unit configured to detect interference patterns between light beams from the surface to be tested and light beams from a reference surface, and a controller configured to control processing for obtaining a figure of the surface to be tested based on the interference patterns detected by the detection unit.

Method for routinely testing and automatically correcting length measuring machine

本发明提供一种测长机日常检测与自动补正方法，包括：步骤1、在预设日常检测时间到达时，判断机台运行状况；步骤2、当机台处于空闲状态时，则停止进片；步骤3、测量机台上用于承载基板的平台上对位标记的坐标值，生成平台测量数据档，并将该测量得到的对位标记坐标值与预设标准坐标值进行对比；步骤4、如果测量的对位标记坐标值与预设标准坐标值之间的差异在预定差异范围内，则自动计算补正量，并将该补正量更新到平台坐标系参数档，完成自动补正；如果测量的对位标记坐标值与预设标准坐标值之间的差异超出预定差异范围，则报警提示；步骤5、根据预判的差异超出预定差异范围的原因，作出继续自动补正、不自动补正或进行大片基板测量确认。

Interferometry testing of lenses, and systems and devices for same

Polarization independent optical coherence-domain reflectometry

A peristaltic pump providing a mechanism for varying tubing occlusion in combination with a camming mechanism which facilitates opening and closing of the pump and including adjustable screw bearing means for effecting fine adjustments in the position of the occlusion bed to thereby vary the occlusion of the tubing.

Cuvette for ophthalmic lens

Modified MZ (Mach-Zender) interferometers are utilized to analyze the transmitted, aspherical wavefront of an ophthalmic lens by mounting the lens in a cuvette having a rotatable carousel that can hold multiple lenses. Fresh, temperature controlled, saline solution is circulated about the lenses, and the cuvette is positioned in a vertical test arm of the interferometer configuration. Reverse raytracing is utilized to remove aberrations induced into the wavefront as it is imaged from immediately behind the lens to the detector of the interferometer.

Measuring apparatus for interferometric shape measurement

A measurement apparatus for interferometric shape measurement of a test object surface. A test optical unit produces from measurement radiation a test wave for irradiating the surface. A reference element with an optically effective surface interacts with a reference wave also produced from the measurement radiation. An interferogram is produced by superimposing the test wave after interaction with the test object's surface. A holding device holds the reference element and moves the reference element relative to the reference wave in at least two rigid body degrees of freedom so that a peripheral point of the reference element's optically effective surface shifts by at least 0.1% of a diameter of the optically effective surface. The at least two degrees of freedom include a translational degree, directed transversely to a propagation direction of the reference wave and a rotational degree, whose rotational axis aligns substantially parallel to the reference wave's propagation direction.

Measurement of complex surface shapes using a spherical wavefront

Conical surfaces (and other complex surface shapes) can be interferometrically characterized using a locally spherical measurement wavefront (e.g., spherical and aspherical wavefronts). In particular, complex surface shapes are measured relative to a measurement point datum. This is achieved by varying the radius of curvature of a virtual surface corresponding to a theoretical test surface that would reflect a measurement wavefront to produce a constant optical path length difference (e.g., zero OPD) between the measurement and reference wavefronts.

System for optical coherence tomography

The invention relates to a system for optical coherence tomography having an interferometer ( 20 ), a detector ( 30 ) with a first number of detector elements for collecting light, and an optical fiber ( 29 ) with a second number of individual fibers for transmitting light from the interferometer ( 20 ) to the detector ( 30 ). In order to increase the compactness of the system with at the same time high image quality provision is made such that the detector elements have a first center-center distance and the individual fibers have a second center-center distance, the first center-center distance between the detector elements being greater than the second center-center distance between the individual fibers.

DEVICE FOR OPTICALLY MEASURING A PHYSICAL PARAMETER

L'invention concerne un dispositif de mesure optique (10) d'un paramètre physique comportant : - une source lumineuse laser (11) pour générer un faisceau de mesure en direction d'une cible (20) et pour recevoir le faisceau de mesure réfléchi par ladite cible, ledit faisceau de mesure parcourant un chemin optique dont la variation est fonction du paramètre physique à déterminer, et ladite source lumineuse laser comportant une cavité optique (111), - un capteur de mouvement (14) de la source lumineuse laser (11), des moyens de calcul (15) du paramètre physique à partir d'un signal mesuré au niveau de la source lumineuse laser (11) et d'un signal mesuré par le capteur de mouvement (14). The invention relates to an optical measuring device (10) for a physical parameter comprising: - a laser light source (11) for generating a measuring beam in the direction of a target (20) and for receiving the reflected measuring beam by said target, said measurement beam traveling an optical path whose variation is a function of the physical parameter to be determined, and said laser light source comprising an optical cavity (111), - a motion sensor (14) of the laser light source ( 11), calculation means (15) of the physical parameter from a signal measured at the laser light source (11) and a signal measured by the motion sensor (14).

INTERFEROMETER FOR DETERMINING PROPERTIES OF AN OBJECT SURFACE

Reduction of coherent artifacts in interferometers