Low stray light polychromator

Technical Field

This invention involves a kind of spectral radiation measurement and spectral analysis device, in particular to a low stray light polychromator.

Background Art

polychromator general includes an optical cavity, an incident slit, dispersion system and array detector, the light beam entering from the incident optical cavity intensity of wideband spectrum corresponding to the slit, the dispersion element is spectrophotometrie, forming different wavelength dispersion of the projected light on a photosensitive surface of the array detector, in order to measure the spectral power distribution. Stray light in the optical system is non-normal transmitted light of the assembly, including stray light intensity of wideband spectrum corresponding to the different diffraction orders overlap and no unintended reflection, stray light intensity measure its performance is one of the important technical indicators.

Overlapping between the different diffraction orders the stray light caused by the filtering by the color filter, instead of the desired reflected light is difficult to eliminate the stray lights. Non-desired reflected light from the optical cavity between each optical element of the optical element and between the optical cavity, in particular, the photosensitive surface of the detector in the array, because the incident angle of the chromatic dispersion light small, a reflected light re-entering the dispersion system very easily, thus bring the considerable stray light; in addition, non-desired reflected light reflected on the inner wall of the optical cavity, may also enter the desired optical path, caused by stray light.

Content of the invention

To address the above disadvantages of the prior art, the invention aims at providing a polychromator , solve in the prior art part of the stray light exists the problem of difficult to eliminate.

In order to achieve the above-mentioned purpose, this invention adopts the following technical scheme:

polychromator a low stray light, including an optical cavity, an incident slit, dispersion system and array detector, characterized in that the dispersion in the dispersion system element is a grating, with the grating array detector the photosensitive surface of the obliquely intersecting the main cross-section.

The above-mentioned grating of the main cross-section of the notch perpendicular to the grating plane.

In the existing polychromator , array detector perpendicular to the photosensitive surface of the main section of the grating, the light rays in the array detector is very easy to occur on the photosensitive surface of the non-desired reflection, and into the desired light path, the introduction of stray light, stray light problems for such, polychromator of the invention by changing the relative position of the optical device, the two-dimensional array detector the photosensitive surface of the main section from the vertical plane of the grating, stray light will produce the original non-desired light path of the reflected light path of the desired light, stray light is reduced.

The invention can be through the following technical characteristics and further defined:

The above-mentioned array detector the photosensitive surface of the main section from the vertical plane of the grating a certain angle, according to the relative position of the optical device, the angle can be set in between 2-12 °, on the array detector photosensitive surface because the reflection of the mirror reflection and the light spot polychromator just deviating from the optical device, and the optical cavity on the surface of the inner wall, to avoid a time array detector the reflected light enters the dispersion system, stray light is reduced. Preferably, the photosensitive surface of the detector array is deviated from the vertical plane of the main section of the grating between 3-10 °, angle is too large, the polychromator placing of the optical device is not compact, the angle is too small, the mechanical process of the high precision requirements.

The above-mentioned dispersion system and the array detector is arranged in the light path between the optical grating obliquely intersecting the main section of the color filter. The color filter through the various light, the role of the restrictions and prevent, can selectively turn on a certain wavelength range of wavelength band, and can eliminate the overlap of the grating spectrum levels. Color filter and obliquely intersects the main cross-section of the grating. The color filter is deviated from the vertical plane of the main section of the grating between 2-12 °, the caused by reflection on the surface of the non-desired light is reflected just the desired light path, thereby reducing the influence of stray light. Preferably, the color filter is deviated from the vertical plane of the main section of the grating between 3-10 °, within the range of the angle, the optical device of the optical cavity polychromator were suitable for compact placement.

The reflective light spot in the optical cavity on the plane of the projection of the inner wall of the installation, the spacing of the small diaphragm, and the inner wall of the optical cavity is uniformly spread small diaphragm surface of low reflectivity of the diffuse reflective material, the installation of the small diaphragm of non-desired light can be increased in the number of times of reflection on the surface of the optical cavity, so as to greatly reduce non-desired the intensity of the light, the light absorption function, in order to reduce or eliminate the reflection light caused by reflection on the wall of the optical cavity to produce the stray light.

The optical cavity is installed on the wall surface of the small diaphragm and the small diaphragm can be uniformly coated on the surface of the specular reflectivity with a diffuse reflective material. At this moment, in the dispersion system and on the path of light between the array detector, detector photosensitive surfaces are arranged in front of a large diaphragm, in order to eliminate the optical cavity and the inner wall of and small diaphragm caused by reflection of stray light. Of big diaphragmsmall diaphragm and can be very effectively removed from the array detector photosensitive surface of the reflection of stray light caused by the light spot.

The above-mentioned dispersion system comprises a collimating element, chromatic dispersion component and a convergent element. Collimating element collects the incident light into parallel light. Chromatic dispersion component has light splitting function, can be the incident beam splitting to form different wavelengths of light, such as prism, grating. Convergence element will come from the desired dispersion element of the parallel beams are converged on the photosensitive surface of the two-dimensional array detector.

The above-mentioned dispersion element may be a plane grating, at this moment the collimating element, a plane grating and a convergent element dispersion system; the dispersive element can also be a concave grating, the grating is a concave surface of a high reflective metal scribing a series of parallel lines the concave surface of a reflective diffraction grating, with spectral and condensing capacity at the same time, the incident slit and array detector constitute polychromator.

The array detector may be a one-dimensional array detector, can also be a two-dimensional array detector, a two-dimensional array detector can be more precisely realize the spectral measurement and analysis, and enhance the drawing efficiency of the spectrum.

The beneficial effects of the invention: this invention is through adjusting the relative position of the optical device, to enable the detector to the photosensitive surface of the main section from the vertical plane of the grating, the radiation will produce stray light is reflected out of the light path is desired, and the inner wall of the optical cavity, the projection reflection facula the plane of the extinction is mounted on the small diaphragm, so as to greatly reduce the stray light.

Description of drawings

Figure 1 is an embodiment of the present invention 1 of the schematic diagram of the structure.

Figure 2 is an embodiment of the present invention 1 of the schematic diagram of the structure.

Figure 3 is an embodiment of the present invention 2 schematic diagram of the structure of.

Figure 4 is an embodiment of the present invention 1 and 2 of the schematic diagram of the structure.

Mode of execution

Embodiment 1

As shown in Figure 1 and Figure 2, a low stray light polychromator , includes an optical cavity, an incident slit 1, dispersion system 2 and array detector 3, in this embodiment of the dispersion element 2 is a concave grating, array detector 3 as a two-dimensional array detector. In this embodiment is defined in shaft z x shaft and: two-dimensional array detector 3 perpendicular to the photosensitive surface of the grating 2 is a main cross-section, through the two-dimensional array detector 3 of the central, and the grating 2 main section and a two-dimensional array detector 3 of photosensitive surfaces intersecting line z shaft is parallel to the axis of; the two-dimensional array detector 3 of the central, and the grating 2 main section and a two-dimensional array detector 3 of photosensitive surfaces intersecting line x vertical axis of the shaft.

Light by incident slit 1-injection, the dispersion system 2 spectrophotometrie convergence, projected onto the two-dimensional array detector 3 on the photosensitive surface of the. Two-dimensional array detector 3 around the photosensitive surface of the shaft to rotate an angle α z, deviate from the grating 2 the vertical plane of the main section, the included angle α is 10 °, as shown in Figure 1 and Figure 2, dotted line position before the rotation of the detector, the detector for the position of the rotary after, before detector rotate, the dispersion system 2 to reach the two-dimensional array detector 3 in the light of its photosensitive surfaces is generated on a time of the reflected light to re-enter the optical path, the dispersion system 2 re-projected onto the two-dimensional array on the photosensitive surface of the detector, thus the introduction of stray light, stray light path as shown in Figure 2 is shown by a dashed line with an arrow; after detector rotate, the dispersion system 2 to reach the two-dimensional array detector 3 in its photosensitive surface on the light reflection from the reflection light spot generated by the optical device of the optical cavity, the wall of the projection in the optical cavity. As shown in Figure 4, the reflected light spot projection plane mounting of extinction small diaphragm 4, and the inner wall of the optical cavity small diaphragm 4 uniformly coated with low reflectivity of the surface of the diffuse reflective material. As shown in Figure 2, the inner wall of the light reflecting and small diaphragmthe spot passes through optical cavity 4 after being reflected a plurality of times, radiation energy is greatly reduced, the resulting reduced as a result of the stray light of the.

Embodiment 2

As shown in Figure 3, a low stray light polychromator , includes an optical cavity, an incident slit 1, dispersion system 2 and array detector 3, the chromatic dispersion in the embodiment of system 2 comprises a collimating element 2-1, dispersion element 2-2 and a convergent element 2-3, dispersion element 2-2 is a plane grating, array detector 3 as a two-dimensional array detector, in this embodiment is defined in shaft z x shaft and: two-dimensional array detector 3 perpendicular to the photosensitive surface of the grating 2 is a main cross-section, through the two-dimensional array detector 3 of the central, and the grating 2 main section and a two-dimensional array detector 3 of photosensitive surfaces intersecting line z shaft is parallel to the axis of; the two-dimensional array detector 3 of the central, and the grating 2 main section and a two-dimensional array detector 3 of photosensitive surfaces intersecting line x vertical axis of the shaft.

Light by incident slit 1-injection, collimating element 2-1 into parallel light by the incident light, chromatic dispersion component 2-2 the incident beam splitting to form different wavelengths of light, the convergence element 2-3 from the dispersion element 2-2 the parallel beams are converged to the desired two-dimensional array detector 3 on the photosensitive surface of the. Two-dimensional array detector 3 around the photosensitive surface of the shaft to rotate an angle α z, deviate from the grating 2 the vertical plane of the main section, the included angle α is 10°. The dispersion system 2 to reach the two-dimensional array detector 3 in its photosensitive surface is on the light generated by reflection of the reflection light spot projection in the optical cavity on the plane of the inner wall, as shown in Figure 4, the reflected light spot projection plane mounting of extinction small diaphragm 4.