A polarization phase shift based optical element stress detection system and method

Abstract

The application belongs to the technical field of optical detection, and particularly relates to an optical element stress detection system and method. The optical element stress detection system based on polarization phase shift comprises a light source module, a polarization detection module and a collection and processing module arranged in sequence. The light source module is used for generating linearly polarized light and outputting a first light beam. The polarization detection module is used for modulating and processing the first light beam passing through the to-be-detected element to generate a second light beam with stress light intensity information of the to-be-detected element. The collection and processing module is used for converging the second light beam to generate a third light beam, and performing calculation and processing on the light intensity information of the collected third light beam to obtain stress information of the to-be-detected element. The application uses a novel optical element detection system to realize stress detection, which can not only avoid problems such as optical path interference and optical interference, but also improve the accuracy and stability of stress detection.

Description

Technical Field

[0001] This invention belongs to the field of optical testing technology, specifically relating to a stress testing system and method for optical components. Background Technology

[0002] Stress distribution is a crucial parameter in stress analysis and detection across fields such as engineering, machinery, aerospace, energy, and transportation. Traditional stress detection methods typically rely on mechanical or electronic sensors, which are not only expensive but also lack sufficient sensitivity and accuracy. Therefore, researching and developing a novel stress detection technology is essential.

[0003] In recent years, stress detection technology based on optical principles has received increasing attention. Optical elements, as a novel type of sensor material, have become a research hotspot in stress detection due to their high sensitivity, non-contact, and non-destructive characteristics. In stress detection using optical elements, polarization phase-shifting technology has been widely used. Its principle is to measure and analyze the stress distribution of an object by analyzing the polarization state and phase changes of light waves.

[0004] However, existing polarization phase-shift stress detection technologies have several limitations. For example, accuracy is affected by factors such as optical path interference and optical interference; signal processing is difficult, requiring complex algorithms and equipment; and achieving automated and high-speed detection is challenging. Therefore, a novel stress detection system based on polarization phase-shift optical elements is needed to address the problems of existing technologies and improve the accuracy and efficiency of stress detection. Summary of the Invention

[0005] The purpose of this invention is to solve the problems existing in the prior art regarding stress detection. Specifically, this invention aims to solve the following problems:

[0006] 1. Insufficient accuracy: Traditional polarization phase-shift stress detection technology is affected by factors such as optical path interference and optical interference, resulting in insufficient measurement accuracy;

[0007] 2. Signal processing difficulties: Existing polarization phase-shift stress detection technologies require complex algorithms and equipment to process signals, and achieving automated and high-speed detection is quite challenging;

[0008] 3. Limited application scope: Existing polarization phase-shift stress detection technology is only applicable to specific types of objects or scenarios, and cannot be widely applied to stress detection in different fields and scenarios.

[0009] To address the aforementioned problems, one technical solution adopted by this invention is to provide a stress detection system for optical components based on polarization phase shift. This system includes: a light source module, a polarization analyzer module, and a data acquisition and processing module arranged sequentially. The light source module generates linearly polarized light and outputs a first beam. The polarization analyzer module modulates the first beam passing through the component under test to generate a second beam carrying stress intensity information of the component under test. The data acquisition and processing module converges the second beam to generate a third beam and calculates the intensity information of the acquired third beam to obtain the stress information of the component under test.

[0010] Preferably, the light source module includes a multi-point light source unit, a beam expander unit, and a polarization modulation unit arranged in sequence; the beam output by the multi-point light source unit is expanded and polarized to generate linearly polarized light.

[0011] Preferably, the polarization detection module includes a quarter-wave plate and a polarizer arranged in sequence; both the quarter-wave plate and the polarizer are connected to an electronic control device for automatic control to rotate to two preset azimuth angles respectively, thereby obtaining light intensity distributions at four different azimuth angles.

[0012] Preferably, the acquisition and processing module includes a beam-gathering unit, an acquisition unit, an image processing unit, and a control unit arranged sequentially; the beam-gathering unit gathers the light carrying the stress intensity information of the element under test; the acquisition unit acquires the intensity image after beam gathering; the image processing unit calculates and processes the acquired intensity image to obtain the stress information of the element under test; and the control unit controls the electronic control device and the acquisition unit.

[0013] Preferably, the image processing unit includes an acquisition module and a calculation module; the acquisition module is connected to the acquisition unit and is used to acquire multiple light intensity information corresponding to the quarter-wave plate and the analyzer at multiple positions; the calculation module is used to calculate the multiple light intensity information to obtain the stress information of the component under test.

[0014] To further solve the above problems, another technical solution adopted by the present invention is to provide a stress detection method for optical elements based on polarization phase shift, including the following steps: (1) obtaining multiple light intensity information corresponding to the quarter-wave plate and analyzer at multiple positions; (2) calculating the stress information of the element under test by using a four-step phase shift interference algorithm based on the multiple light intensity information.

[0015] Preferably, the multiple positions of the quarter-wave plate refer to positions where the relative angle between the fast axis of the quarter-wave plate and the polarization plane of the polarization modulation unit is ±45°.

[0016] Preferably, the multiple positions of the analyzer refer to rotating the analyzer to any two positions in any two orientations for each position of the quarter-wave plate, with the angles of the two orientations differing by 45°.

[0017] Preferably, step (2) specifically includes: acquiring multiple light intensity information corresponding to the quarter-wave plate and analyzer at multiple positions; calculating factors containing the phase delay and fast axis orientation of the element under test at different azimuth angles of the analyzer based on the multiple light intensity information, while eliminating non-uniformity factors; generating the phase delay and fast axis orientation of the element under test based on the factors containing the phase delay and fast axis orientation of the element under test at different azimuth angles of the analyzer based on the multiple light intensity information, and calculating the stress information of the element under test.

[0018] Compared with existing polarization phase shift stress detection technologies, this invention has the following advantages:

[0019] 1. High precision: This invention utilizes a novel optical element design to achieve stress detection, which not only avoids problems such as optical path interference and optical interference, but also improves the accuracy and stability of stress detection.

[0020] 2. Simple and easy to implement: This invention uses simple optical components and structures, requires no complex algorithms and equipment, is easy to operate, and is suitable for automated detection and high-speed detection needs.

[0021] 3. Wide applicability: The stress detection system based on polarization phase shift optical elements designed in this invention can be applied to stress detection needs in different fields and scenarios, and has broad application prospects. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of an optical element stress detection system based on polarization phase shift in an embodiment of the present invention;

[0023] Figure 2 This is a schematic flowchart of the stress detection method for optical elements based on polarization phase shift in an embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of the data acquisition and processing module in an embodiment of the present invention;

[0025] Figure 4 They are equivalent vector triangles;

[0026] Figure 5 These are equivalent triangles before and after rotation;

[0027] Figure 6 The azimuth angle of the analyzer;

[0028] In the figure: 1-Light source module; 11-Multi-point light source unit; 12-Beam expander unit; 13-Polarization modulation unit; 2-Component under test; 3-Polarization analyzer module; 31-Quarter-wave plate; 32-First precision rotary motor; 33-Analyzer; 34-Second precision rotary motor; 4-Acquisition and processing module; 41-Beam gatherer unit; 42-Acquisition unit; 43-Image processing unit; 5-Stage. Detailed Implementation

[0029] To facilitate understanding of the present invention, it will be described in more detail below with reference to the accompanying drawings and specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0030] Example 1: The stress detection system for optical elements based on polarization phase shift provided by the present invention has the following structure: Figure 1 As shown, it includes a light source module 1, a polarization detection module 3, an acquisition and processing module 4, and a control module arranged in sequence.

[0031] in:

[0032] The light source module 1 outputs a multi-point light source, which is then expanded and polarized into linearly polarized light to generate a first beam. Specifically, the light source module 1 includes a multi-point light source unit 11, a beam expander unit 12, and a polarization modulation unit 13 arranged sequentially. The multi-point light source unit 11 outputs a multi-point beam, which can be visible light, infrared light, microwave, etc., to accommodate different devices under test 2. The beam expander unit 12 expands the multi-point beam into a surface light source. The polarization modulation unit 13 modulates the polarization of the surface light source to generate linearly polarized light.

[0033] As a feasible implementation, the multi-point light source unit 11 can specifically be a 20W monochromatic (590nm) LED with good power uniformity and polarization state, and it consists of 100 2835 590nm SMD LED chips forming a light source with an area of ​​200mm×200mm. The beam expanding unit 12 can specifically be a 200mm×200mm light homogenizing plate. The polarization modulation unit 13 uses a polarizer that can rotate around the optical axis of the optical path, for example, a thin-film polarizer with a size of 200mm×200mm, a wavelength of 400~700nm, and an extinction ratio of 1:1000 can be selected.

[0034] The polarization analyzer module 3 is used to rotate the quarter-wave plate and the analyzer at two preset angles to generate four second beams of light with different phases carrying stress intensity information of the element under test 2. The polarization analyzer module 3 specifically includes: a quarter-wave plate 31, a first precision rotary motor 32 that drives the quarter-wave plate 31 to rotate, an analyzer 33, and a second precision rotary motor 34 that drives the analyzer to rotate, arranged sequentially. The first precision rotary motor 32 can rotate the quarter-wave plate 31 around the optical axis of the optical path, setting the fast axis of the quarter-wave plate 31 and the polarization plane of the polarization modulation unit 13 to two azimuth angles of ±45°, so as to modulate the linearly polarized beam output from the light source module 1 into circularly polarized light. The analyzer 33 can be a thin-film polarizer with dimensions of 200mm×200mm, wavelength of 400~700nm, and extinction ratio of 1:1000. The second precision rotary motor 34 rotates the analyzer 33 to two preset angles. It should be noted that the first precision rotary motor 32 and the second precision rotary motor 34 only need to be able to rotate the quarter-wave plate 31 and the analyzer 34 to a preset position, and this application does not impose too many restrictions on their specific models.

[0035] The acquisition and processing module 4 is used to converge the second beam formed after the first beam passes through the element under test 2 and the polarization analyzer 3 to generate a third beam, and to acquire the intensity information of the third beam. The acquired image information is processed to obtain the stress information of the element under test 2. The acquisition and processing module 4 specifically includes: a convergence unit 41, an acquisition unit 42, and an image processing unit 43 arranged in sequence.

[0036] As a feasible implementation, the focusing unit 41 can specifically be a lens with a focal length of 1000mm and a diameter of 200mm. The acquisition unit 42 can specifically be a Daheng Mercury Generation 1 USB 3.0 color camera with a resolution of 2592×1944 and 5 million pixels, model MER-500-14U3C-L. The image processing unit 43 can be a computer with image processing software, and can include an acquisition module and a calculation module. The acquisition module is used to acquire multiple light intensity information corresponding to the quarter-wave plate and analyzer at multiple positions, and the calculation module is used to calculate the multiple light intensity information to obtain the stress information of the component under test. It should be noted here that the image processing unit 43 only needs to be able to process the image and calculate the stress information of the component under test 2.

[0037] The acquisition and processing module 4 also includes a control unit, which is used to adjust and control the rotation angles of the first precision rotary motor 32 and the second precision rotary motor 34, and also to control the acquisition unit 42 to acquire the third beam. This control unit can be a hardware product, such as a controller, or a software control system; this application does not impose further limitations on this.

[0038] In this embodiment, the element under test 2 can specifically be a circular flat glass plate with a diameter of 40 mm and a thickness of 3 mm, formed by two-point pressing, and the corresponding linearly polarized light is visible light. The element under test 2 can also be a transparent element, such as a silicon-based chip, and the corresponding linearly polarized light is infrared light. The element under test 2 is placed on the stage 5, located at the center of the light field.

[0039] The stress detection system proposed in this application operates as follows: The white light output from the light source module 1 is expanded and polarized to generate a first beam. After passing through the element under test 2, a first precision rotary motor 32, controlling the rotation of a quarter-wave plate, rotates the quarter-wave plate 31 to two positions according to a set angle under the control of the control unit. A second precision rotary motor 34, controlling the rotation of the analyzer, rotates the analyzer 33 to two positions according to a set angle under the control of the control unit, thereby generating four second beams of light with different phases, each carrying stress intensity information of the element under test 2. A beam-gathering unit 41 gathers the second beams to generate a gathered beam, i.e., a third beam. An acquisition unit 42, under the control of the control unit, acquires four intensity information images and transmits the acquired images to an image processing unit 43. The image processing unit processes the acquired image information to obtain the stress information of the element under test.

[0040] Example 2 This example provides a stress detection method for optical elements based on polarization phase shift. This method is based on the system in Example 1, and specifically, the acquisition and processing module in this system can be configured according to... Figure 2 The process shown includes the following steps:

[0041] S201, acquire multiple light intensity information corresponding to the quarter-wave plate and analyzer at multiple positions.

[0042] In this embodiment, the optical axis of the optical path is selected as the z-direction, and an experimental reference system xy coordinate system is established in the plane perpendicular to the optical axis of the optical path, where the x-direction is the horizontal direction and the y-direction is perpendicular to the x-direction in the plane perpendicular to the optical axis of the optical path. The first precision rotary motor 32, which controls the rotation of the quarter-wave plate, rotates the quarter-wave plate 31 around the optical axis of the optical path, setting the fast axis of the quarter-wave plate 31 and the polarization plane of the polarization modulation unit 13 to two azimuth angles of ±45°. The second precision rotary motor 34, which controls the rotation of the analyzer, rotates the analyzer 33 to two preset angles of 112.5° and 67.5°. The acquisition unit 42 acquires light intensity information at four combined angles and transmits it to the image processing unit 43.

[0043] S202 calculates the factors of phase delay and fast axis orientation of the stress birefringence of the element under test under different azimuth angles of the analyzer based on the acquired multiple light intensity information.

[0044] The phase delay factor τ(x,y) of analyzer 33 at different azimuth angles was calculated based on four light intensity information maps. AR And the fast axis orientation factor τ(x,y) AT Simultaneously, the non-uniformity factor γ(x,y) is eliminated. The specific process is as follows:

[0045] (1) The linearly polarized light output from light source module 1 vibrates in the horizontal direction, and the Stokes vector is as follows:

[0046]

[0047] Among them, I in The incident light intensity is given. The beam then passes through a quarter-wave plate 31, whose Miller matrix is:

[0048]

[0049] Let the stress birefringence phase delay distribution at each point of the element under test 2 be as follows: If the azimuth distribution of the fast axis is θ(x,y), then the Miller matrix representing the information of each point of the measured element 2 is:

[0050]

[0051] The analyzer 33 needs to be rotated to two different azimuth angles ρ AT =112.5°, ρ AR =67.5°, where ρ represents the azimuth angle of the analyzer in the matrix below:

[0052]

[0053] At this point, the Miller matrices of the entire system can be multiplied to obtain the final light intensity distribution on the detector:

[0054] D = A·S·Q·P (5)

[0055] Substituting matrices (1) to (4) into equation (5), the first term D0 of the outgoing light Stokes vector D is extracted to obtain the two-dimensional light intensity distribution on the receiving surface of the acquisition unit 42:

[0056]

[0057] Where τ(x,y) is an important parameter, its specific form is:

[0058]

[0059] It can be seen that the stress birefringence phase retardation distribution of the element under test 2 is present. The azimuth angle distribution θ(x,y) of the fast axis and the azimuth angle of the analyzer allow the information of the sample to be extracted by rotating the analyzer 33. The non-uniformity factor γ(x,y) in the above formula is an important parameter distinguishing two-dimensional stress measurement from single-point measurement. For a practical two-dimensional measurement system, beam non-uniformity is an unavoidable problem. The detection system in Example 1 consists of three parts: a light source module, a control and analysis module, and an acquisition and processing module. For the beam emitted from the beam expander 12, the intensity distribution is generally Gaussian, which is obviously non-uniform on the two-dimensional plane. Moreover, the beam expander 12 cannot completely and uniformly expand the beam; the beam passes through many optical elements during propagation, and the defects and transmission characteristics of the optical element surfaces exacerbate the non-uniformity. Non-uniform response of the imaging detection system also exists. Therefore, the overall effect of the above three parts produces a considerable degree of system non-uniformity. Scattering from dust in the air, etc., all contribute to the non-uniformity of the two-dimensional plane, which is an important characteristic distinguishing it from single-point measurement.

[0060] For this system, eliminating the inhomogeneity of the system is not complicated. By rotating the quarter-wave plate 31 and the analyzer 33, the γ(x,y) factor can be eliminated while resolving the sample phase and fast axis azimuth. The specific steps are as follows: (1) First, fix the transmission direction of the analyzer 33 as ρ. AR At this point, rotating the quarter-wave plate by 31 degrees to change its fast-axis azimuth to -45 degrees, its Miller matrix becomes:

[0061]

[0062] Substituting the matrix Q of the rotated quarter-wave plate 31 into the system polarization state transfer equation (Equation 5), we can obtain the Stokes vector of the outgoing light and the distribution of the outgoing light intensity on the receiving surface of the acquisition unit 42:

[0063]

[0064] The intensity distribution of the emitted light before the quarter-wave plate 31 is rotated is as follows:

[0065]

[0066] Combining the above two equations, we can extract the factor τ(x,y) to obtain:

[0067]

[0068] (2) Next, rotate the analyzer 33 to another angle ρ. AT Using the same method, the intensity distribution of the emitted light before and after rotating the quarter-wave plate 31 can be obtained respectively:

[0069]

[0070]

[0071] Similarly, the analyzer 33ρ is obtained. AT The τ(x,y) factor at azimuth angle:

[0072]

[0073] It can be seen that by rotating the quarter-wave plate 31 to different orientations, the τ(x,y) factor containing the phase delay of sample stress birefringence and fast axis orientation can be obtained. At the same time, the non-uniform factor γ(x,y) in the above two equations is eliminated, further improving the two-dimensional measurement system.

[0074] S203, calculate the stress information of the element under test based on the stress birefringence phase retardation and fast axis orientation factor, specifically including the following steps:

[0075] (1) From τ(x,y) AR and τ(x,y) AT Extracting from factors And θ(x,y). From equation (7), it can be seen that the factor τ(x,y) is mathematically composed of two sinusoidal factors. The relationship between sin[2ρ-2θ(x,y)] and sin[2ρ-2θ(x,y)] can be expressed by... Figure 4 To indicate:

[0076] Depend on Figure 4 It can be seen that, Let τ(x,y) be the length of side OA, τ(x,y) be the length of the vertical component AB of OA, and the angle AOB represent 2ρ-2θ(x,y). Let the azimuth angle ρ of the analyzer 33 be two different angles ρ... AR and ρ AT Different values ​​of τ(x,y) can be obtained. AR (x,y) and τ AT (x,y), which means obtaining the different vertical components AB of OA. This is equivalent to rotating the analyzer 33 while the vector OA continues to rotate along point O, and when the angle after rotation is as follows... Figure 5 As shown.

[0077] Clearly, triangles OAB and OCD are congruent at this point, and τ AR (x,y) and τ AT (x, y) are the two legs of a right triangle, and the hypotenuse contains a phase delay component. The angular change caused by rotating the analyzer 33 (marked by dashed line) from 2ρ AR -2θ(x,y) to 2ρ AT -2θ(x,y) has rotated exactly 90 degrees. Therefore, it is easy to obtain the angular relationship between the analyzer 33 before and after rotation:

[0078] [2ρ AT -2θ(x,y)]-[2ρ AR -2θ(x,y)]=2(ρ AT -ρ AR )=90° (14)

[0079] The above formula shows that only the analyzer 33 needs to be rotated 90 degrees. However, for the sake of simplicity, let:

[0080]

[0081] Therefore, the azimuth angle ρ of the analyzer 33 is obtained. AT =112.5°, ρ AR =67.5°, such as Figure 6 As shown.

[0082] At this point, τ AR (x,y) and τ AT (x,y) can also be obtained:

[0083]

[0084]

[0085] Finally, the stress birefringence phase retardation distribution and fast axis azimuth distribution of the tested element 2 are obtained by the following formula:

[0086]

[0087]

[0088] The formula (17) is used to calculate the result. The phase retardation of stress birefringence can be obtained by taking the square root of the inverse trigonometric function.

[0089] When the stress birefringence phase retardation is measured When the stress birefringence δ is reached, it can be calculated using the following formula. n (nm / cm):

[0090]

[0091] In the formula, λ is the phase delay due to stress birefringence, λ is the wavelength of the light source, and d is the thickness of the sample being measured.

[0092] In summary, the embodiments of this application only require the acquisition of four light intensity information maps under a polarized light field to perform stress detection. During detection, a full-aperture light beam needs to pass through the component under test (DUT), using this beam as the target for detection. Most DUT components are weakly interferometric samples without fine structures. Loading the information of the DUT into the illumination light reduces errors in phase-shifting interferometry, avoids size limitations imposed by the scanning, and thus enables accurate stress detection of large-sized components. Simultaneously, it reduces the requirements for the scanning translation stage and avoids polarization aberrations during spherical wave illumination. The four-step phase-shifting interferometry method greatly simplifies the experimental process, accelerates the experimental speed, and reduces the amount of data required for subsequent processing, making it highly applicable.

Claims

1. A method for stress detection of optical elements based on polarization phase shift, characterized in that, Includes the following steps: (1) Obtain multiple light intensity information corresponding to the quarter-wave plate and analyzer at multiple positions; (2) Calculate the stress information of the component under test using a four-step phase-shifting interferometry algorithm based on the multiple light intensity information, specifically: calculate the factors containing the phase delay and fast axis orientation of the component under test under different azimuth angles of the analyzer based on the multiple light intensity information, and eliminate non-uniformity factors: (1) First, fix the transmission direction of the analyzer as At this point, rotating the quarter-wave plate to -45 degrees on its fast axis results in the following Miller matrix: (8) Substituting the matrix Q after rotating the quarter-wave plate into the system polarization state transfer equation, we obtain the Stokes vector of the outgoing light and the distribution of the outgoing light intensity on the receiving surface of the acquisition unit: (9) The intensity distribution of the emitted light before the quarter-wave plate is rotated is as follows: (10) Combining the above two equations will Factor extraction yields: (11) (2) Next, rotate the analyzer to another angle. Using the same method, the intensity distribution of the emitted light before and after rotating the quarter-wave plate was obtained respectively: (12) Similarly, the analyzer is obtained. Azimuth angle factor: (13) By rotating the quarter-wave plate to different orientations, phase retardation due to sample stress birefringence and fast-axis orientation can be obtained. Factors, and non-uniform factors It was eliminated; Based on the multiple light intensity information, factors containing the phase delay and fast axis azimuth of the element under test (DUT) are calculated at different azimuth angles of the analyzer. This generates the phase delay and fast axis azimuth angle of the DUT, and the stress information of the DUT is calculated. The angular relationship before and after analyzer rotation is also obtained. (14) At this point, and get: (16) and These are the two legs of a right triangle; The hypotenuse has a phase delay component; The stress birefringence phase retardation distribution and fast axis azimuth distribution of the element under test are obtained by the following formula: (17) The formula (17) is used to calculate the result. The phase retardation of stress birefringence can be obtained by taking the square root of the inverse trigonometric function. φ ; When the stress birefringence phase retardation is measured φ When, the stress birefringence is calculated using the following formula. δ n (nm / cm): (18) In the formula, φ This is the phase retardation due to stress birefringence. λ The wavelength of the light source, d The thickness of the sample being measured.

2. The method for stress detection of optical elements based on polarization phase shift according to claim 1, characterized in that, In step (1), the multiple positions of the quarter-wave plate refer to the positions where the relative angle between the fast axis of the quarter-wave plate and the polarization plane of the polarization modulation unit is ±45°.

3. The method for stress detection of optical elements based on polarization phase shift according to claim 2, characterized in that, In step (1), multiple positions of the analyzer refer to rotating the analyzer to any two positions in any two directions for each position of the quarter-wave plate, with the angles of the two directions differing by 45°.

4. A system for implementing the method of claim 1, characterized in that, include: The light source module, polarization detection module, and data acquisition and processing module are set up sequentially. The light source module is used to generate linearly polarized light and output a first beam; The polarization detection module is used to modulate the first beam passing through the component under test to generate a second beam carrying the stress intensity information of the component under test; the acquisition and processing module is used to converge the second beam to generate a third beam. The intensity information of the collected third beam is then calculated and processed to obtain the stress information of the component under test.

5. The system according to claim 4, characterized in that, The light source module includes a multi-point light source unit, a beam expander unit, and a polarization modulation unit arranged in sequence; the beam output by the multi-point light source unit is expanded and polarized to generate linearly polarized light.

6. The system according to claim 4, characterized in that, The polarization analysis module includes a quarter-wave plate and an analyzer arranged in sequence; both the quarter-wave plate and the analyzer are connected to an electronic control device, which rotates to a set position under the action of an electric device to obtain light intensity distributions in multiple different positions.

7. The system according to claim 4, characterized in that, The acquisition and processing module includes a beam-gathering unit, an acquisition unit, an image processing unit, and a control unit arranged sequentially. The beam-gathering unit gathers the light carrying the stress intensity information of the element under test. The acquisition unit acquires the intensity image after beam gathering. The image processing unit calculates and processes the acquired intensity image to obtain the stress information of the element under test. The control unit controls the electronic control device and the acquisition unit.

8. The system according to claim 7, characterized in that, The image processing unit includes an acquisition module and a calculation module; the acquisition module is connected to the acquisition unit and is used to acquire multiple light intensity information corresponding to the quarter-wave plate and analyzer at multiple positions; The calculation module is used to calculate the multiple light intensity information and the stress information of the component under test.

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