A polarization imaging detection device and detection method based on elastic-photoelectric modulation

Abstract

The invention discloses a polarization imaging detection device and a detection method based on elastic-photoelastic modulation, comprising an illumination device, an elastic-photoelastic polarization modulation imaging system, a CCD imaging detector and a control system. The control system is composed of a control computer, an FPGA control circuit and a switch circuit. The control system is characterized in that a flash-frequency scattering light homogenization device is used as an illumination device, and the high time resolution characteristic of the FPGA control circuit is utilized. By connecting with the switch circuit, the CCD imaging detector and the elastic-photoelastic polarization modulation imaging system, a periodic square wave voltage signal and pulse signals of different phases of the same frequency are output to the elastic-photoelastic polarization modulation imaging system and the switch circuit respectively, and a square wave trigger signal is output to control the CCD imaging detector at the same time, thereby ensuring the synchronization of the illumination moment and the elastic-photoelastic modulation driving amplitude selection, and being able to effectively achieve the speed matching between the elastic-photoelastic polarization modulation imaging system and the imaging CCD, so as to achieve the polarization imaging detection of the sample quickly, sensitively and with high precision.

Description

Technical Field

[0001] The present invention relates to a polarization imaging detection technology, and in particular to a polarization imaging detection device and a detection method based on elastic-photoelectric modulation. Background Art

[0002] As we all know, biological samples such as collagen fibers, filamentous actin, microtubules, spindles, and two-dimensional materials such as black phosphorus, rhenium disulfide, and germanium phosphide all show anisotropy in optical properties. Effectively detecting and analyzing the anisotropic characteristics of samples can provide effective auxiliary means for the study of the morphology, structure and function of biological samples and the structure and performance regulation of two-dimensional material crystals. At present, the research on optical anisotropy applied to biological samples and two-dimensional materials is mainly through optical polarization microscopy, but the existing polarization microscopy systems mostly use rotating polarizers or rotating wave plates, or liquid crystal variable phase retarders as core components. Polarization imaging devices using rotating polarizers or rotating wave plates as core components have the advantages of large aperture and low cost, but rotating polarizers or rotating wave plates use mechanical rotating mechanisms, which not only have limited imaging detection speed, but also cause imaging beam drift, reducing polarization detection sensitivity and accuracy; while liquid crystal variable phase retarders are easily affected by temperature, the working stability of polarization imaging systems is limited, and the phase delay switching speed of liquid crystal variable phase retarders is limited, and the polarization imaging speed is slow. Therefore, in order to meet the growing testing needs in the fields of biomedicine, nanomaterials, etc., it is urgent to break through the key technologies of high-speed and high-precision polarization-resolved microscopy.

[0003] Photoelastic modulation has the advantages of high operating frequency, high modulation purity, large aperture, good anti-vibration performance, etc., and provides an excellent modulation method for polarization detection. At present, the commonly used photoelastic modulator generally has an operating frequency of tens of kHz, and a typical operating frequency of 50kHz. In a complete working cycle of 20μs, it can realize the modulation of any phase delay amplitude in the range of 0 to 2π, which makes it possible for high-speed and high-precision polarization-resolved microscopy. However, the frame rate of the current imaging CCD array detector is generally in the order of hundreds to tens of fps, and the time required for each image acquisition is in the order of ms. In order to use photoelastic modulation to realize high-speed polarization imaging detection, it is necessary to solve the difficulty of the photoelastic modulation device and the imaging CCD being unable to achieve coordinated work due to speed mismatch. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a polarization imaging detection device and detection method based on photoelastic modulation, in which the speed of the photoelastic polarization modulation imaging system and the imaging CCD are matched with each other, and the sample detection can be realized quickly, sensitively and with high precision.

[0005] One of the technical solutions adopted by the present invention to solve the above-mentioned technical problems is: a polarization imaging detection device based on elastic light modulation, including an illumination device, an elastic light polarization modulation imaging system, a CCD imaging detector and a control system. The illumination device is a flash scattering uniform light device. The control system is composed of a control computer, an FPGA control circuit and a switch circuit. The control computer is connected to the FPGA control circuit and the CCD imaging detector. The FPGA control circuit is connected to the elastic light polarization modulation imaging system and the CCD imaging detector. The FPGA control circuit is connected to the illumination device through the switch circuit. The control computer sends the elastic light modulation cycle to the FPGA control circuit. After the FPGA control circuit is controlled by the timing, the output The FPGA control circuit outputs a periodic square wave voltage signal to the photoelastic polarization modulation imaging system to drive it to generate a periodic photoelastic modulation signal. At the same time, the FPGA control circuit outputs a pulse signal with the same frequency but different phase as the periodic square wave voltage signal to the switch circuit. The switch circuit outputs the pulse signal to the lighting device after power amplification to drive it to work, and the photoelastic polarization modulation imaging system generates a polarization image corresponding to the phase of the periodic photoelastic modulation signal. The FPGA control circuit outputs a square wave trigger signal to control the CCD imaging detector to collect the polarization image output by the photoelastic polarization modulation imaging system. The CCD imaging detector transmits the collected polarization image to the control computer to complete the demodulation and analysis of the polarization image, and extracts the polarization information of the sample to be tested.

[0006] The specific relationship between the periodic square wave voltage signal, the periodic light-elastic modulation signal and the pulse signal is as follows: the square wave width of the periodic square wave voltage signal is equal to the interval length between two adjacent square waves, at the leading edge position of the periodic square wave voltage signal, there is a first pulse signal, and the periodic light-elastic modulation signal is 0; at the high level position of the periodic square wave voltage signal, there is a second pulse signal at one-sixth of the pulse width, and there is a third pulse signal at one-half of the pulse width, the periodic light-elastic modulation signal is between 0 and 180 degrees, and the signal is positive; at the trailing edge position of the periodic square wave voltage signal, the periodic light-elastic modulation signal is 0; at the zero level position of the periodic square wave voltage signal, the periodic light-elastic modulation signal is between 180 and 360 degrees, and the signal is negative.

[0007] The lighting device is composed of a light source and a scattering element. The switch circuit is connected to the light source. The switch circuit outputs the pulse signal to the light source after power amplification to drive the light source to work.

[0008] The light sources are LEDs or semiconductor laser diodes that are closely arranged in an array.

[0009] There are 16 LEDs or semiconductor diodes, which are closely arranged in a hexagonal array, and the diameter of the light-transmitting surface is 2 cm.

[0010] The scattering element is frosted glass or a diffuse transmission screen.

[0011] The frosted glass is polished to a 600-mesh specification.

[0012] The photoelastic polarization modulation imaging system is composed of a polarizer, an LC resonant driving circuit, a photoelastic modulator and an analyzer. The FPGA control circuit is connected to the LC resonant driving circuit, and the LC resonant driving circuit is connected to the photoelastic modulator. The periodic square wave voltage signal output by the FPGA control circuit is amplified by the LC resonant driving circuit to drive the photoelastic modulator to generate a periodic photoelastic modulation signal, and the polarization image is output by the analyzer.

[0013] The pulse width of the periodic square wave voltage signal is 100-300ns, and the frequency of the photoelastic modulation cycle is 40-80kHz.

[0014] The second technical solution adopted by the present invention to solve the above technical problem is: a method for performing sample polarization imaging detection using the above detection device, the specific steps are as follows:

[0015] S1, placing the sample to be tested in the photoelastic polarization modulation imaging system, and sending the photoelastic modulation cycle to the FPGA control circuit by the control computer;

[0016] S2, after the timing control, the FPGA control circuit outputs a periodic square wave voltage signal to the photoelastic polarization modulation imaging system to drive it to work and generate a periodic photoelastic modulation signal, and at the same time, the FPGA control circuit outputs a pulse signal with the same frequency but different phase as the periodic square wave voltage signal to the switch circuit and outputs a square wave trigger signal to the CCD imaging detector;

[0017] S3, the switch circuit outputs the pulse signal after power amplification to the lighting device to drive it to work, and the photoelastic polarization modulation imaging system generates a polarization image corresponding to the phase of the periodic photoelastic modulation signal, and the square wave trigger signal controls the CCD imaging detector to collect the polarization image output by the photoelastic polarization modulation imaging system;

[0018] S4, after the CCD imaging detector collects the polarization image output by the photoelastic polarization modulation imaging system, the polarization image is transmitted to the control computer;

[0019] S5. The control computer demodulates and analyzes the received polarization image, extracts the polarization information of the sample to be tested, and completes the polarization imaging detection of the sample.

[0020] In one cycle of the periodic square wave voltage signal, the photoelastic polarization modulation imaging system sequentially generates polarization images I0, I1 corresponding to the three phase positions of 0°, 30° and 90° of the periodic photoelastic modulation signal. 30 and I 90 The CCD imaging detector collects polarization images and transmits them to the control computer, which calculates the polarization images according to the formula and The polarization information demodulation of the sample to be tested is completed, and finally the polarization imaging detection of the sample to be tested is completed. In the formula: Δ is the phase difference of the polarization component of the light transmitted through the sample to be tested, and Ψ is the amplitude ratio of the polarization component of the light transmitted through the sample to be tested.

[0021] Compared with the prior art, the advantages of the present invention are as follows: a flash-scattering uniform light device is used as a lighting device, and the high time resolution characteristic of the FPGA control circuit is utilized. By connecting with a switch circuit, a CCD imaging detector and an elastic-light polarization modulation imaging system, a periodic square wave voltage signal and a pulse signal of the same frequency but different phases are output to the elastic-light polarization modulation imaging system and the switch circuit respectively, and a square wave trigger signal is output to control the CCD imaging detector at the same time, thereby ensuring the synchronization of the lighting moment and the elastic-light modulation driving amplitude selection, and being able to effectively achieve the speed matching between the elastic-light polarization modulation imaging system and the imaging CCD, so as to realize the polarization imaging detection of the sample quickly, sensitively and with high precision; the lighting device of the present invention selects a plurality of LEDs or semiconductor laser diodes with a flash function and arranges them in an array, and then sets frosted glass or diffuse light behind the light source. The transmission screen acts as a scattering element, and the arrayed LEDs or semiconductor laser diodes become extended light sources after passing through frosted glass or diffuse transmission screens. The extended light source not only has a large luminous flux but also has a uniform illumination area. The polarization degree of the entire light source is reduced, which is convenient for application in different polarization directions. The processing technology of LED or semiconductor laser diode sources is mature and the price is cheap. Both light sources have low power consumption, high luminous efficiency, and low required driving power. In addition, both light sources have a wide range of available optical bands within the visible and near-infrared spectrum, providing a better light source choice to meet the polarization imaging research of different biological samples and new materials. While maintaining a large array light source and high luminous flux, the array LED or semiconductor laser diode ensures the synchronization of light emission on the entire surface light source, providing a high time precision control guarantee for the control of the start and end time of the flash lighting technology and the flash repetition cycle control. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the structure of a polarization imaging detection device based on photoelastic modulation according to an embodiment of the present invention:

[0023] In the figure, 1: light source; 2: scattering element; 3: switching circuit; 4: photoelastic polarization modulation imaging system, 4-1: polarizer, 4-2: LC resonant drive circuit unit, 4-3: photoelastic modulator, 4-4: sample to be tested, 4-5: analyzer, 4-6: CCD imaging detector; 5: FPGA control circuit; 6: control computer.

[0024] Figure 2 Schematic diagram of working signals according to an embodiment of the present invention.

[0025] In the figure: t is time, Sr is a periodic square wave voltage signal, P1, P2 and P3 are pulse signals with the same frequency as the periodic square wave voltage signal Sr and phases of 0°, 30° and 90° respectively, δ is a periodic photoelastic modulation signal, and St is a square wave trigger signal for controlling the operation of the CCD imaging detector. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below with reference to the accompanying drawings.

[0027] Example: Figure 1 As shown, the polarization imaging detection device based on elastic-photoelectric modulation of the present invention comprises a light source 1, a scattering element 2, a switching circuit 3, a polarizer 4-1, an LC resonant driving circuit 4-2, an elastic-photoelectric modulator 4-3, an analyzer 4-5, a CCD imaging detector 4-6, an FPGA control circuit 5 and a control computer 6, wherein: the light source 1 is 16 LEDs or semiconductor laser diodes tightly arranged in a hexagonal array, and the diameter of the light-transmitting surface is 2 cm, the scattering element 2 is a diffuse transmission screen or frosted glass with a polishing specification of 600 meshes, the control computer 6 is connected to the FPGA control circuit 5 and the CCD imaging detector 4-6, the FPGA control circuit 5 is connected to the LC resonant driving circuit 4-2 and the CCD imaging detector 4-6 in the elastic-photoelectric polarization modulation imaging system 4, the LC resonant driving circuit 4-2 is connected to the elastic-photoelectric modulator 4-3, the FPGA control circuit 5 is connected to the switching circuit 3, and the switching circuit 3 is connected to the light source 1.

[0028] Use as Figure 1 The method for performing polarization imaging detection by the detection device shown in the figure has the following specific steps:

[0029] S1, placing the sample 4-4 to be tested in the photoelastic polarization modulation imaging system 4, between the photoelastic modulator 4-3 and the analyzer 4-5, and sending the photoelastic modulation cycle with a frequency of 50kHz to the FPGA control circuit 5 by the control computer 6;

[0030] S2, after the timing control, the FPGA control circuit 5 outputs a periodic square wave voltage signal Sr with a pulse width of 100ns to the LC resonance driving circuit 4-2, and after amplification, drives the photoelastic modulator 4-3 to work and generate a periodic photoelastic modulation signal δ. At the same time, the FPGA control circuit 5 outputs pulse signals P1, P2 and P3 of the corresponding periodic photoelastic modulation signal δ with the same frequency as the periodic square wave voltage signal Sr and the phases of which are 0°, 30° and 90° respectively to the switch circuit 3. At the same time, the FPGA control circuit 5 outputs a square wave trigger signal St to control the CCD imaging detector 4-6;

[0031] S3, the switch circuit 3 outputs the pulse signal after power amplification to the light source 1 to drive it to work, and the polarization image I0, I1 corresponding to the phase is output by the polarizer 4-5. 30 and I 90 , and at the same time, the FPGA control circuit 5 outputs a square wave trigger signal St to control the CCD imaging detector 4-6 to collect the polarization image output by the analyzer 4-5;

[0032] S4, CCD imaging detector 4-6 collects polarization images I0, I 30 and I 90 After that, the polarization images I0, I 30 and I 90 Transmitted to the control computer 6;

[0033] S5, control computer 6 to receive polarization images I0, I 30 and I 90 By formula and Complete the polarization information demodulation analysis of the sample 4-4 to be tested, extract the polarization information of the sample 4-4 to be tested: the phase difference Δ of the polarization component of the light transmitted through the sample 4-4 to be tested and the amplitude ratio Ψ of the polarization component of the light transmitted through the sample 4-4 to be tested, and finally complete the polarization imaging detection of the sample 4-4 to be tested.

[0034] Generally speaking, the transmission axis of the polarizer 4-1 is set at 45°, the transmission axis of the analyzer 4-5 is set at -45°, the transmission axes of the polarizer 4-1 and the analyzer 4-5 are perpendicular to each other, and the modulation axis of the elastic modulator 4-3 is set at 0°. The light after passing through the polarizer 4-1 can be expressed by the Stokes parameter S in =(I0,0,I0,0) T, where I0 is the total incident light intensity reaching the elastic light modulator 4-3 after the light passes through the polarizer 4-1. The elastic light modulator 4-3 works in resonance and exhibits a periodic phase delay value modulation, which can be described as δ=δ0sin(2πf0t), where δ0 is the phase modulation amplitude, and f0 is the resonant operating frequency of the elastic light modulator 4-3, which is generally tens of kHz, and a typical value is 50kHz. It can be seen from the phase delay value modulation of the elastic light modulator 4-3 that within one elastic light modulation cycle, the elastic light modulator 4-3 can traverse all phase delay values ​​within the range of (-δ0, δ0) in the form of a sine function. The polarization transmission characteristics of the elastic light modulator 4-3 can be described by the Muller matrix as

[0035]

[0036] After being modulated by the photoelastic modulator 4-3, it enters the sample to be tested 4-4. The photoelastic modulation polarization imaging system 4 described in this patent is mainly used for polarization imaging analysis of biological samples and thin film materials to be tested. Biological samples and thin film two-dimensional material samples use an optical film equivalent optical model, and the polarized light transmission of the sample film layer can be described by elliptical optics, that is, the p-polarized light component and the s-polarized light component of the transmitted light can be described as

[0037]

[0038] Among them, the two ellipsometric angles ψ and Δ represent the amplitude ratio and phase difference of the p-polarized light component and the s-polarized light component of the transmitted light, respectively. The polarization characteristics of the sample to be tested can be further described by the Mueller matrix as

[0039]

[0040] Among them, the Mueller matrix of the -45° analyzer is expressed as

[0041]

[0042] For the polarization imaging characteristics analysis of the photoelastic modulation polarization imaging system 4, the system is analyzed by using the Stokes parameter and Mueller polarization transmission matrix, and ignoring the light transmission loss, it can be concluded that the Stokes parameter emitted by the analyzer 4-5 and reaching the CCD imaging detector 4-6 is

[0043] S out =M A M S M PEM S in (5)

[0044] Substituting (1), (2), (3), and (4) into equation (5), we can solve the light intensity obtained on each pixel of the CCD imaging detector 4-6, which can be described by the Stokes first component as:

[0045]

[0046] It can be seen from the above formula that the polarization information of the sample to be tested is loaded into the phase modulation signal of the photoelastic modulator 4-3. The phase modulation value δ=δ0sin(2πf0t) of the photoelastic modulator 4-3 is modulated at a high speed with an operating frequency of tens of kHz, and the typical value is 50kHz. However, the exposure time of conventional CCD imaging detectors is now in the ms range. Obviously, the faster modulation speed of the photoelastic modulation is not matched with the slower imaging speed of the CCD. The present invention aims to solve this difficulty. When the phase modulation values ​​of the photoelastic modulator are 0°, 30° and 90°, it is lit, and the CCD imaging detector is used to collect the light intensity corresponding to each phase modulation value.

[0047]

[0048] From equation (7), we can first solve the phase difference of the two polarized lights transmitted through the sample:

[0049]

[0050] Substituting the phase difference into equation (7) to transform the following equation, we can further solve the amplitude ratio of the two polarized lights transmitted through the sample:

[0051]

[0052] According to the above analysis, the key to realize photoelastic modulation polarization imaging is to obtain the polarization imaging light intensity when the phase modulation value of the photoelastic modulator is 0°, 30° and 90° respectively. Figure 2 It can be seen from the working signal principle diagram shown that the following relationship exists between the periodic square wave voltage signal Sr, the pulse signals P1, P2 and P3 with phases of 0°, 30° and 90° respectively, and the periodic light-elastic modulation signal δ: the pulse width of the periodic square wave voltage signal Sr is equal to the interval length between two adjacent pulses, at the leading edge position of the periodic square wave voltage signal Sr, there is a first pulse signal P1 with a phase of 0°, and the periodic light-elastic modulation signal δ is 0; at the high level position of the periodic square wave voltage signal Sr, there is a second pulse signal P2 with a phase of 30° at one-sixth of the pulse width, and there is a third pulse signal P3 with a phase of 90° at one-half of the pulse width, and the periodic light-elastic modulation signal δ is between 0 and 180 degrees, and the signal is positive; at the trailing edge position of the periodic square wave voltage signal Sr, the periodic light-elastic modulation signal δ is 0; at the zero level position of the periodic square wave voltage signal Sr, the periodic light-elastic modulation signal δ is between 180 and 360 degrees, and the signal is negative.

[0053] The number of pulses depends on the exposure time of the CCD imaging detector. The typical value is generally set to 50 photorejuvenation cycles, 50 repeated pulses, and a 1ms time interval trigger signal S. t Trigger the CCD imaging detector to collect images. Using a CCD detector with higher quantum conversion efficiency, the exposure time can be further shortened, the polarization imaging speed can be further improved, and the polarization imaging detection of a large aperture can be completed at ultra-high speed. The analysis has the advantages of in-situ, high-precision, high-sensitivity, multi-channel and high-detection-flux polarization imaging detection applications.

[0054] The drawings and embodiments described herein are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in more detail with reference to the preferred embodiments, those skilled in the art should understand that the specific implementation methods of the present invention may still be modified or some technical features may be replaced by equivalents without departing from the spirit of the present invention, which should all be included in the scope of the technical solution for which protection is requested by the present invention.

Claims

1. A polarization imaging detection device based on elastic photomodulation, comprising an illumination device, an elastic photopolarization modulation imaging system, a CCD imaging detector and a control system, characterized in that: The lighting device is a flash-frequency scattering and uniform light device. The control system is composed of a control computer, an FPGA control circuit and a switch circuit. The control computer is connected to the FPGA control circuit and the CCD imaging detector. The FPGA control circuit is connected to the elastic light polarization modulation imaging system and the CCD imaging detector. The FPGA control circuit is connected to the lighting device through the switch circuit. The control computer sends the elastic light modulation period to the FPGA control circuit. After timing control, the FPGA control circuit outputs a periodic square wave voltage signal to the elastic light polarization modulation imaging system to drive it to work and generate a periodic elastic light modulation signal. At the same time, the FPGA control circuit outputs a pulse signal of the same frequency but different phase as the periodic square wave voltage signal to the switch circuit. The switch circuit outputs the pulse signal to the lighting device after power amplification to drive it to work, and the elastic light polarization modulation imaging system generates a polarization image corresponding to the phase of the periodic elastic light modulation signal. The FPGA control circuit The output square wave trigger signal controls the CCD imaging detector to collect the polarization image output by the elastic light polarization modulation imaging system. The CCD imaging detector transmits the collected polarization image to the control computer to complete the demodulation analysis of the polarization image and extract the polarization information of the sample to be tested. The periodic square wave voltage signal, the periodic elastic light modulation signal and the pulse signal have the following relationship: the square wave width of the periodic square wave voltage signal is equal to the interval length between two adjacent square waves. At the leading edge position of the periodic square wave voltage signal, there is a first pulse signal, and the periodic elastic light modulation signal is 0; at the high level position of the periodic square wave voltage signal, there is a second pulse signal at one-sixth of the pulse width, and there is a third pulse signal at one-half of the pulse width. The periodic elastic light modulation signal is between 0 and 180 degrees, and the signal is positive; at the trailing edge position of the periodic square wave voltage signal, the periodic elastic light modulation signal is 0; at the zero level position of the periodic square wave voltage signal, the periodic elastic light modulation signal is between 180 and 360 degrees, and the signal is negative.

2. The polarization imaging detection device based on elastic photomodulation according to claim 1, characterized in that: The lighting device is composed of a light source and a scattering element. The switch circuit is connected to the light source. The switch circuit outputs the pulse signal to the light source after power amplification to drive the light source to work.

3. The polarization imaging detection device based on elastic photomodulation according to claim 2, characterized in that: The light sources are LEDs or semiconductor laser diodes that are closely arranged in an array.

4. The polarization imaging detection device based on photoelastic modulation according to claim 3, characterized in that: The LEDs or semiconductor laser diodes are 16 in number and are closely arranged in a hexagonal array, and the diameter of the light-transmitting surface is 2 cm.

5. The polarization imaging detection device based on elastic photomodulation as claimed in claim 2, characterized in that: The scattering element is frosted glass or a diffuse transmission screen.

6. The polarization imaging detection device based on photoelastic modulation according to claim 5, characterized in that: The frosted glass is polished to a 600-mesh specification.

7. The polarization imaging detection device based on photoelastic modulation according to claim 1, characterized in that: The photoelastic polarization modulation imaging system is composed of a polarizer, an LC resonant driving circuit, a photoelastic modulator and an analyzer. The FPGA control circuit is connected to the LC resonant driving circuit, and the LC resonant driving circuit is connected to the photoelastic modulator. The periodic square wave voltage signal output by the FPGA control circuit is amplified by the LC resonant driving circuit to drive the photoelastic modulator to generate a periodic photoelastic modulation signal, and the polarization image is output by the analyzer.

8. The polarization imaging detection device based on photoelastic modulation according to claim 1, characterized in that: The pulse width of the periodic square wave voltage signal is 100-300ns, and the frequency of the photoelastic modulation cycle is 40-80kHz.

9. A method for performing sample polarization imaging detection using the detection device according to claim 1, characterized in that: The specific steps are as follows: S1, placing the sample to be tested in the photoelastic polarization modulation imaging system, and the control computer sends the photoelastic modulation cycle to the FPGA control circuit; S2, after the timing control, the FPGA control circuit outputs a periodic square wave voltage signal to the photoelastic polarization modulation imaging system to drive it to work and generate a periodic photoelastic modulation signal, and at the same time, the FPGA control circuit outputs a pulse signal with the same frequency but different phase as the periodic square wave voltage signal to the switch circuit and outputs a square wave trigger signal to the CCD imaging detector; S3, the switch circuit outputs the pulse signal after power amplification to the lighting device to drive it to work, and the photoelastic polarization modulation imaging system generates a polarization image corresponding to the phase of the periodic photoelastic modulation signal, and the square wave trigger signal controls the CCD imaging detector to collect the polarization image output by the photoelastic polarization modulation imaging system; S4, after the CCD imaging detector collects the polarization image output by the photoelastic polarization modulation imaging system, the polarization image is transmitted to the control computer; S5. The control computer demodulates and analyzes the received polarization image, extracts the polarization information of the sample to be tested, and completes the polarization imaging detection of the sample.

10. The method for polarization imaging detection according to claim 9, characterized in that: In one cycle of the periodic square wave voltage signal, the photoelastic polarization modulation imaging system sequentially generates polarization images corresponding to the three phase positions of 0°, 30° and 90° of the periodic photoelastic modulation signal. I 0. I 30 and I 90 The CCD imaging detector collects polarization images and transmits them to the control computer, which calculates the polarization images according to the formula and Complete the demodulation of the polarization information of the sample to be tested, and finally complete the polarization imaging detection of the sample to be tested, where: Δ is the phase difference of the polarization component of the light transmitted through the sample to be tested, Ψ It is the amplitude ratio of the polarization components of the light transmitted through the sample to be tested.

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