Seismic physical model fiber laser ultrasonic imaging system

Technical Field

The invention belongs to the technical field of seismology, in particular to a seismic physical model optical fiber laser ultrasonic imaging system.

Background Art

Earthquake physical model is based on the storage of the geological structure of the MROM rock simulated structure. Earthquake physical model ultrasonic imaging technique is ultrasonic transmitting and scanning collecting geological model information of the internal structure of the acoustic signal, to ground shock wave in various complex geologic spread in the laboratory in the analog observation, and according to the inversion algorithm to reconstruct the three-dimensional structure model, to seismology research. The present commonly used ultrasonic detection method generally adopts a piezoelectric type ultrasonic probe for ultrasonic transmitting and receiving, when the solid materials at the time of measurement, the transmitting probe and receiving probe close to the surface of the object to be measured, emitting head will narrow pulse electrical signal is converted into the ultrasonic signal, the receiving head is the ultrasonic signal into the electrical signal. In addition, piezoelectric ultrasonic probe can only narrow band transmission or reception, so that the measurement does not reflect the field construction broadband transmitting and receiving the actual situation; sound wave receiving directivity is strong, has a small azimuth, the spatial resolution is poor; appropriate to the target single-point detection, reusability difference; easy to electromagnetic interference, signal long-distance transmission ability is poor, is not conducive to remote monitoring. The above limitations of complex seismic physical model is difficult to meet the high-resolution imaging of the demand.

Content of the invention

The invention aims to solve the technical problem of providing a high measuring precision, the operation is convenient, bandwidth, without damage to the seismic physical model, the non-contact seismic physical model optical fiber laser ultrasonic imaging system.

To solve the above technical problem by adopting the technical proposal is: in the pulse laser on the optical platform laser exit direction are arranged sequentially in the spatial light modulator and an optical fiber collimator, optical fiber collimator by high power optical fiber connected to the optical fiber lens, optical fiber lens located in the upper part of the physical model, seismic physical model of optical and acoustic coated on the surface of the functional coating, close to the seismic physical model of the optical fiber arranged on the surface of the ultrasonic sensor, optical platform is sequentially provided with a tunable laser, optical fiber circulators, photoelectric detector, optical fiber ultrasonic sensor, tunable laser and photoelectric detector through the optical fiber with the optical fiber ring connecting the, photoelectric detector through a coaxial cable is connected with a data acquisition card, data acquisition card through the data line is connected with the computer.

As a preferred embodiment, the optical fiber lens is a conical or spherical optical fiber lens 5.

As a preferred embodiment, the conical optical fiber lens has a diameter of 125 - 400 μm, cone angle is 30° -60°; spherical optical fiber lens has a diameter of 125 - 400 μm.

As a preferred embodiment, the acousto-optic functional coating material is gold foil or graphene or tungsten disulfide.

The beneficial effect of the present invention are as follows:

The optical fiber laser ultrasonic imaging technique, is a non-contact, high-precision, broadband, multi-mode, no damage model ultrasonic imaging technique. As a-optical ultrasound imaging system, can be used for ultrasonic imaging, non-destructive testing for structure, oil and gas fields of the physical model imaging, elastic wave velocity modeling, biological and medical technical field.

Description of drawings

Figure 1 is the structure diagram of the invention.

Figure 2 is the invention detecting organic glass block up and down time domain spectrum of the ultrasonic signal reflected by the reflecting surface.

Figure 3 is the data inversion of computer visualization algorithm to acquisition.

Mode of execution

The Figure below and embodiment of the invention described in greater detail, but the invention is not limited to the following embodiments.

Embodiment 1

In fig. 1 in, the embodiment of the seismic physical model optical fiber laser ultrasonic imaging system by the tunable laser 1, pulse laser 2, the spatial light modulator 3, the optical fiber collimator 4, optical fiber lens 5, optical fiber ultrasonic sensor 8, computer 9, optical fiber circulator 10, data acquisition card 11, the photoelectric detector 12, optical platform 13 connected to form.

In the optical platform 13 on the pulse laser 2 laser light is arranged sequentially in the direction of the spatial light modulator 3 and optical fiber collimator 4, optical fiber collimator 4 through high power optical fiber with the optical fiber lens 5 connected, optical fiber lens 5 is located in the earthquake physical model 7 above, seismic physical model 7 coated on the surface of gold foil coating 6, pulse laser 2 emitted from the laser incident to the spatial light modulator 3 is modulated, the spatial light modulator 3 modulation of the laser after incident optical fiber collimator 4, optical fiber collimator 4 laser coupled to an optical fiber, the optical fiber collimator 4 through high power optical fiber with the optical fiber lens 5 connected, optical fiber lens 5 is a conical optical fiber lens, conical optical fiber lens diameter of 250 μm, cone angle is 45°, optical fiber lens 5 after the input focus the laser output, the output of the laser irradiation to the located in the physical model 7 the surface of the gold foil coating 6 on, the use of photoacoustic effect should produce ultrasonic signals to the seismic physical model 7 internal, focusing of the laser beam in the seismic physical model 7 surface scanning, to form a continuous linear sound source, optical fiber ultrasonic sensor 8 close to the seismic physical model 7 surface, for acquiring seismic physical model 7 and the internal surface of the ultrasonic echo signal, optical platform 13 is sequentially provided with a tunable laser 1, the optical fiber of the circulator 10, the photoelectric detector 12, tunable laser 1 exit narrowband laser through optical fiber circulator 10 reach the ultrasonic sensor 8, optical fiber ultrasonic sensor 8 reflected optical signal through the optical fiber circulator 10 enters the photoelectric detector 12, the photoelectric detector 12 the input optical signal into an electric signal and inputted into the data acquisition card 11, the photoelectric detector 12 through coaxial cable and data acquisition card 11 is connected with the, data acquisition card 11 with the computer 9 communication, computer 9 to the input data to obtain the inversion of seismic data imaging.

Embodiment 2

In the optical platform 13 on the pulse laser 2 laser light is arranged sequentially in the direction of the spatial light modulator 3 and optical fiber collimator 4, optical fiber collimator 4 through high power optical fiber with the optical fiber lens 5 connected, optical fiber lens 5 is located in the earthquake physical model 7 above, seismic physical model 7 coated on the surface of gold foil coating 6, pulse laser 2 emitted from the laser irradiation to the spatial light modulator 3 is modulated, the spatial light modulator 3 modulation of the laser after incident optical fiber collimator 4, optical fiber collimator 4 laser coupled to an optical fiber, the optical fiber collimator 4 through the optical fiber with the optical fiber lens 5 connected, optical fiber lens 5 is a conical optical fiber lens, conical optical fiber lens has a diameter of 125 μm, cone angle is 30°. Optical fiber lens 5 after the focus the laser output, the output of the laser irradiation to the located in the physical model 7 the surface of the gold foil coating 6 on, the use of photoacoustic effect should produce ultrasonic signals to the seismic physical model 7 internal. The focusing of the laser beam in the seismic physical model 7 surface scanning, to form a continuous linear source, optical fiber ultrasonic sensor 8 close to the seismic physical model 7 surface, for acquiring seismic physical model 7 surface and internal ultrasonic echo signal. The optical platform 13 is sequentially provided with a tunable laser 1, the optical fiber of the circulator 10, the photoelectric detector 12, tunable laser 1 exit narrowband laser through optical fiber circulator 10 reach the ultrasonic sensor 8, optical fiber ultrasonic sensor 8 reflected optical signal through the optical fiber circulator 10 enters the photoelectric detector 12, the photoelectric detector 12 the input optical signal into an electric signal and inputted into the data acquisition card 11, the photoelectric detector 12 through coaxial cable and data acquisition card 11 connected, data acquisition card 11 with the computer 9 communication, computer 9 to the input of the data processing, get the inversion of seismic data imaging.

Embodiment 3

In the optical platform 13 on the pulse laser 2 laser light is arranged sequentially in the direction of the spatial light modulator 3 and optical fiber collimator 4, optical fiber collimator 4 through high power optical fiber with the optical fiber lens 5 connected, optical fiber lens 5 is located in the earthquake physical model 7 above, seismic physical model 7 coated on the surface of gold foil coating 6, pulse laser 2 emitted from the laser irradiation to the spatial light modulator 3 is modulated, the spatial light modulator 3 modulation of the laser after incident optical fiber collimator 4, optical fiber collimator 4 laser coupled to an optical fiber, the optical fiber collimator 4 through the optical fiber with the optical fiber lens 5 connected, optical fiber lens 5 is a conical optical fiber lens, conical optical fiber lens has a diameter of 400 μm, cone angle is 60°. Optical fiber lens 5 after the focus the laser output, the output of the laser irradiation to the located in the physical model 7 the surface of the gold foil coating 6 on, the use of photoacoustic effect should produce ultrasonic signals to the seismic physical model 7 internal, focusing of the laser beam in the seismic physical model 7 surface scanning, to form a continuous linear source, optical fiber ultrasonic sensor 8 close to the seismic physical model 7 surface, for acquiring seismic physical model 7 surface and internal ultrasonic echo signal. The optical platform 13 is sequentially provided with a tunable laser 1, the optical fiber of the circulator 10, the photoelectric detector 12, tunable laser 1 exit narrowband laser through optical fiber circulator 10 reach the ultrasonic sensor 8, optical fiber ultrasonic sensor 8 reflected optical signal through the optical fiber circulator 10 enters the photoelectric detector 12, the photoelectric detector 12 the input optical signal into an electric signal and inputted into the data acquisition card 11, the photoelectric detector 12 through coaxial cable and data acquisition card 11 connected, data acquisition card 11 with the computer 9 communication, computer 9 to the input of the data processing, and through the imaging algorithm to realize the inversion of seismic data imaging.

Embodiment 4

In the above-mentioned embodiment 1 - 3 in, seismic physical model 7 coated on the surface of the graphene coating, can also be a tungsten disulfide coating. Other parts and connected with the corresponding parts of the embodiment of the relationship between the same.

Embodiment 5

In the above-mentioned embodiment 1 - 3 in, optical fiber lens 5 is a spherical optical fiber lens, the diameter is 300 μm, can also be a 125 μm, can also be a 400 μm. Other parts and connected with the corresponding parts of the embodiment of the relationship between the same

In order to verify that the beneficial effect of the invention, the inventor according to the embodiment of the invention 1 the structure of the following experiment:

The water in the inside of the water tank, a water tank placed at the bottom of one end of a 5 cm × 4 cm × 4 cm of the organic glass block, the bottom surface of the organic glass block with 1 cm deep groove, for detecting seismic physical model 7 surface and an internal dimension the reflected pulse ultrasonic signal; measuring when the foil coating in the seismic physical model 7 on the upper surface, is placed in the system of the present invention, pulse laser 2 issued 532 nm nanosecond laser irradiation model surface gold foil, stimulates the pulse of the ultrasonic signal, pulse of the ultrasonic signal is transmitted to the organic glass plate through the water after, a portion of the acoustic wave signal directly by surface reflection on the organic glass plate, the other part of the transmission to the lower surface after reflection, the reflected ultrasonic signal by the optical fiber ultrasonic sensor 8 receiving; adjustable laser as a light source, its line width and resolution are 100 KHz and 0.1 pm; tunable laser 1 issued by the narrow line width of the laser through the optical fiber circulator 10 is transmitted to the optical fiber of the ultrasonic sensor 8, optical fiber ultrasonic sensor 8 reflected modulated optical information through the optical fiber ultrasonic sensor 8 is transmitted to the optical fiber of the circulator 10, re-transmission to the photoelectric detector 12, the optical signal is converted to a voltage signal, through the coaxial cable transmission to the data acquisition card 11, through the computer 9 analysis.

Experimental results:

The experimental results as shown in Figure 2, 3 is shown. Figure 2 is the invention detecting organic glass block up and down time domain spectrum of the ultrasonic signal reflected by the reflecting surface. The ultrasonic sensor through the optical fiber 8 scanning imaging, then the computer 9 visualization algorithm to the collected data inversion, can be Figure 3, can be observed clearly in the Figure to the model of the upper and lower surface of the imaging result. The invention as a-optical ultrasound imaging system, can be used for ultrasonic imaging, non-destructive testing for structure, oil and gas fields of the physical model imaging, elastic wave velocity modeling, biological and medical technical field.