Optical element multi-dimensional parameter single exposure measuring device and measuring method

Abstract

The invention discloses an optical element multi-dimensional parameter single exposure measuring device and measuring method, and relates to the technical field of multi-parameter measurement, the device comprises an illumination system, a polarizer, a sample to be measured, a lens, a modulation plate, a data acquisition system and a data processing system; the illumination system is composed of a coherent light source and a collimation system and provides a beam of coherent illumination light with the diameter of about 5 mm for the system. The polarizer is arranged behind the illumination system and is used for converting the light beam into illumination light in a specific polarization state; through optical path design and a data processing algorithm, accurate measurement of multi-dimensional parameters such as the amplitude, the phase and the birefringence of the optical element can be completed through single exposure, the measurement time is greatly shortened, the measurement process which possibly needs several hours and even longer time originally is compressed to be instantly completed through single exposure, and the measurement efficiency is greatly improved. And the measurement efficiency is greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-parameter measurement, and particularly to a device and method for measuring multi-dimensional parameters of an optical element by single exposure. Background Art

[0002] In the field of optics, the performance evaluation of optical elements is of great importance. Multi-dimensional parameters such as amplitude, phase, and birefringence are key indicators for measuring the quality of optical elements. These parameters can accurately reflect the modulation characteristics of optical elements on light, and have a profound impact on the design, manufacturing, and performance optimization of optical systems. For example, in many applications such as optical communication, optical imaging, and optical sensing, the accurate measurement of multi-dimensional parameters of optical elements can ensure the stability and reliability of the system, thereby improving the overall performance.

[0003] Traditional methods for measuring multi-dimensional parameters of optical elements have many limitations and are difficult to meet the requirements of efficient and accurate measurement in the modern optical field. On the one hand, traditional methods usually require multiple exposures to complete the measurement of different parameters. Each exposure requires precise adjustment of the parameters and state of the measurement system, which undoubtedly greatly increases the measurement time. In the actual measurement process, multiple exposures are also affected by environmental changes such as temperature, humidity, vibration, etc. These changes may cause inconsistent measurement conditions during each exposure, thereby introducing large measurement errors. On the other hand, the steps of traditional measurement methods are often relatively complex. The acquisition of amplitude, phase, and birefringence information often relies on step-by-step measurement or the combination of different technologies. For example, the phase information of a light beam is measured using interferometry, digital holography, or lattice beam wavefront analysis methods, and the birefringence information is solved using multi-wavelength methods, phase-shift methods, or step-by-step loading methods. Such solutions not only require complex optical path switching and multi-frame image registration, but also are difficult to apply to high-throughput detection of living dynamic samples or light-sensitive materials due to problems such as high cumulative light dose and low time resolution. Summary of the Invention

[0004] The purpose of the present invention is to make up for the deficiencies of the existing technology, and provide a device and method for measuring multi-dimensional parameters of an optical element by single exposure. It can integrate an illumination system, a polarizer, a sample to be measured, a lens, a modulation plate, a data acquisition system, and a data processing system, and use optical path design and data processing algorithms to achieve accurate measurement of multi-dimensional parameters such as amplitude, phase, and birefringence of an optical element by single exposure. In the measurement method, single exposure data acquisition is performed by setting different polarization directions, and the collected data is processed using an iterative algorithm to gradually reconstruct the light field distribution, and then the birefringence information of the sample is solved.

[0005] To solve the above technical problems, the present invention provides the following technical solutions: an optical element multi-dimensional parameter single-exposure measurement device and a measurement method, and the method includes the following specific steps: an illumination system, a polarizer, a sample to be measured, a lens, a modulation plate, a data acquisition system, and a data processing system;

[0006] The illumination system is composed of a coherent light source and a collimation system, and provides a coherent illumination light beam with a diameter of about 5 mm for the system;

[0007] The polarizer is arranged behind the illumination system and is used to convert the light beam into illumination light of a specific polarization state;

[0008] The sample to be measured is placed behind the polarizer;

[0009] The lens is placed behind the sample to be measured, and first focuses and then diverges the illumination light;

[0010] The modulation plate is placed behind the focal point and is used for modulating the illumination light;

[0011] The data acquisition system is arranged behind the modulation plate and is used for acquiring diffraction spots;

[0012] The data processing system is connected to the data acquisition system, processes the acquired diffraction spots, and reconstructs the amplitude, phase, and birefringence distribution maps of the sample to be measured through an iterative algorithm.

[0013] Further, the polarizer is a linear polarizer with an extinction ratio of not less than 1000:1.

[0014] Furthermore, the modulation plate is a phase-type modulation plate.

[0015] Furthermore, the data acquisition system is a polarization camera, which can simultaneously record the intensity information in four polarization directions, and one of the light transmission directions is the same as the light transmission direction of the polarizer, and is arranged behind the modulation plate.

[0016] On the other hand, an optical element multi-dimensional parameter single-exposure measurement method, and the method includes the following components:

[0017] Optical path setting and initial light field preparation: the coherent light emitted by the illumination system forms illumination light of a specific polarization state after passing through the polarizer and irradiates the sample to be measured. The illumination light irradiating the sample to be measured continues to propagate, is first focused and then diverged by the lens placed behind the sample to be measured, and a phase-type modulation plate with a known distribution is placed behind the focal point of the lens for modulating the illumination light;

[0018] Single-exposure data acquisition: The data acquisition system records the modulated diffraction spot. The through-light direction angles of the polarization camera are 0°, 45°, 90°, and 135° respectively, and four polarization images are acquired.

[0019] Iterative reconstruction of the light field distribution: The four polarization images acquired by single-exposure are transmitted to the data processing system. The iterative algorithm is used to reconstruct the amplitude, phase, and birefringence distribution maps of the sample to be measured. The light field on the camera plane is represented in complex form. The amplitude part in the complex form is replaced with the recorded intensity information, and the updated light field is transmitted in the direction opposite to the light propagation to the encoding board surface to remove the modulation effect of the modulation board on the illuminating light, obtaining the incident light distribution on the modulation board surface. This incident light distribution is reversely transmitted back to the focal plane. With the focal plane as the constraint condition, the updated wavefront distribution of the focal plane is obtained.

[0020] Calculation of birefringence information and determination of parameters: After multiple iterations, the accurate light field distribution at the focus is obtained. This light field distribution is reversely transmitted back to the lens to remove the phase effect of the lens on the light field, and then continues to be reversely transmitted back to the sample to obtain the amplitude and phase distributions of the transmission function of the sample in four polarization directions. Using the complex amplitude information in the four polarization directions, the birefringence information of the sample is solved, that is, the angle between the polarizer and the main axis X of the stress point and the phase difference between the two beams of light are determined. Through the calculation and analysis of relevant physical quantities, the principal stress difference is finally obtained.

[0021] Furthermore, in the single-exposure data acquisition step, the data acquisition system records the modulated diffraction spot. During the recording process, assume that the linearly polarized illuminating light after the polarizer is , which becomes elliptically polarized light after passing through the sample , and then is focused by the lens and irradiated onto the modulation board surface. The modulation board is placed downstream of the focus. One through-light direction of the polarization camera is parallel to the polarizer, and the angles are 0°, 45°, 90°, and 135° respectively. The acquired diffraction spots are denoted as . The transmission process of the illuminating light from the sample to the polarization camera is expressed as: , where represents the light field distribution at the focus, represents the light field distribution on the camera, is the transmission operator related to the focal length of the lens, is the focal length of the lens, is the transmission operator from the sample to the lens, represents the distance from the sample to the lens, is the transmission operator from the focus to the modulation board, is the distance from the focus to the modulation board, is the transmission operator from the modulation plate to the camera, is the distance from the modulation plate to the camera.

[0022] Furthermore, in the step of iteratively reconstructing the light field distribution, an iterative algorithm is used to reconstruct the amplitude, phase, and birefringence distribution maps of the sample to be measured. Specifically, in the th iteration, the light field on the camera plane is written in complex form, i.e., , where, is the complex form of the light field on the camera plane in the th iteration and the th polarization direction, is the amplitude of this light field, is the phase of this light field, and the amplitude is replaced with the intensity information recorded by the camera, where, is the intensity information of the th iteration and the th polarization direction recorded by the camera. The updated light field is reversely transmitted to the encoding plate surface , where, is the light field distribution reversely transmitted to the encoding plate surface, is the reverse transmission operator related to the distance from the modulation plate to the camera. After removing the modulation of the modulation plate, the incident light distribution on the modulation plate surface is obtained, where, is the incident light distribution on the modulation plate surface, is the complex conjugate of the modulation plate phase function, is the maximum value of the square of the modulus of the modulation plate phase function, is the light field distribution on the focal plane in the th iteration. The is reversely transmitted back to the focal plane, , where, is the reverse transmission operator related to the lens focal length . Using the focal plane as a constraint, the updated wavefront distribution on the focal plane is obtained, where, is the wavefront distribution on the focal plane in the th iteration, R is the aperture function that changes with the number of iterations, and the relaxation factor . Repeat the iteration to obtain the light field distribution at the focus, reversely back-propagate to the lens, remove the phase of the lens, and then reversely back-propagate to the sample to obtain the transmission function of the sample of the amplitude and phase distributions in four polarization directions, i.e., .

[0023] Furthermore, in the step of calculating birefringence information and determining parameters, the birefringence information of the sample is solved by using the complex amplitudes in four polarization directions, that is, the angle between the polarizer and the main axis of the stress point is solved, as well as the phase difference between the two beams of light , and its calculation formula is: , where is the amplitude in different polarization directions, is the amplitude parameter related to the birefringence of the sample, representing the initial amplitude component not affected by birefringence, is the angle between the light transmission direction of the polarizer and the main axis of the stress point of the sample , which is used to characterize the direction characteristics of birefringence, is the phase difference between the two orthogonally polarized light beams in the sample, reflecting the intensity of birefringence. Solving the system of equations gives , substituting into , obtaining an expression of independent of , , and further obtaining the principal stress difference , where and are the principal stresses in two perpendicular directions at the stress point, is the wavelength of the illuminating light, is the reduced Planck constant, is the stress-strain coefficient of the sample, which is used to characterize the conversion relationship between stress and birefringence.

[0024] Compared with the prior art, the one-time exposure measurement device and measurement method for multi-dimensional parameters of an optical element have the following beneficial effects:

[0025] First, through the optical path design and data processing algorithm, the present invention realizes the accurate measurement of multi-dimensional parameters such as amplitude, phase, and birefringence of an optical element with a single exposure, greatly shortening the measurement time. The measurement process that originally might take several hours or even longer is compressed to be completed in an instant of a single exposure, significantly improving the measurement efficiency. At the same time, since the measurement process is completed within a single exposure, it effectively reduces the measurement errors caused by environmental factors such as temperature fluctuations and air disturbances, significantly improving the accuracy and stability of the measurement, and meeting the requirements of modern optical fields for high-efficiency and precise measurement.

[0026] Second, by designing the device structure and measurement method, the present invention can accurately reconstruct the amplitude, phase, and birefringence distribution maps of the sample to be measured. The iterative algorithm is used to process the four polarization images collected by a single exposure, fully considering various physical effects during the propagation of light, making the measurement results highly accurate.

[0027] Other advantages, objectives and features of the present invention will be set forth to some extent in the subsequent description, and to some extent, will be apparent to those skilled in the art based on the study of the following text, or can be learned from the practice of the present invention. Description of the Drawings

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0029] Figure 1 It is a schematic diagram of a device for measuring multi-dimensional parameters of an optical element by single-shot exposure;

[0030] Figure 2 It is a flowchart of a method for measuring multi-dimensional parameters of an optical element by single-shot exposure;

[0031] In the figure: 1. Illumination system; 2. Polarizer; 3. Sample to be measured; 4. Lens; 5. Modulation plate; 6. Data acquisition system. Detailed Embodiments

[0032] To further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention objective, the following will, in conjunction with the drawings and preferred embodiments, detail the specific embodiments, structures, features and their effects of the present invention as follows.

[0033] Embodiment 1

[0034] The measuring device consists of an illumination system 1, a polarizer 2, a sample to be measured 3, a lens 4, a modulation plate 5, a data acquisition system 6 and a data processing system. As Figure 1 shown, each component is arranged in sequence along the light propagation direction in the optical path. The illumination system 1 provides a coherent illumination light beam with a diameter of about 5 mm for the entire measuring system. The coherent light emitted by it directly enters the polarizer 2. The two are in a front-back sequence in the optical path to ensure that the light can pass through the polarizer 2 smoothly.

[0035] The polarizer 2 converts the light provided by the illumination system 1 into linearly polarized light with a specific polarization state. Its light transmission direction is vertically upward, and the extinction ratio is 10000:1. The polarizing sheet only allows light vibrating in a specific direction to pass through. When the coherent light is incident on the polarizer 2, only the light with the vibration direction consistent with the light transmission direction of the polarizer 2 can pass through, and the light vibrating in other directions is greatly attenuated, thereby obtaining high-quality linearly polarized light. The emitted linearly polarized light irradiates the sample to be measured 3.

[0036] The sample to be measured 3 is located behind the polarizer 2. As the object to be measured, its optical properties will modulate the amplitude, phase, and polarization state of the incident light. When linearly polarized light passes through the sample to be measured 3, due to the anisotropy of the sample, the propagation speed and attenuation degree of light in different directions of the sample are different, resulting in the attenuation of the light amplitude, the delay of the phase, and the change of the polarization state from linearly polarized light to elliptically polarized light. These changes contain the amplitude, phase, and birefringence information of the sample.

[0037] The light modulated by the sample to be measured 3 is incident on the lens 4. The lens 4 is located behind the sample to be measured 3 and performs focusing and diverging operations on the light. According to the imaging principle of the lens 4, when the light exits from the sample to be measured 3 and passes through the lens 4, refraction will occur. When the light is incident on the lens 4, it will be converged by the lens 4 to the focal point, forming a focal point. Then, after the focal point, the light starts to diverge again. Through this focusing and diverging process, the propagation path of the light is restricted, making the spatial distribution of the light meet the requirements of subsequent modulation and data acquisition.

[0038] The light exiting from the lens 4 reaches the modulation plate 5. The modulation plate 5 is set at the downstream position of the focal point of the lens 4 and is used to further modulate the light. The modulation plate 5 itself does not change the amplitude of the light, but modulates the phase of the light to be measured through its specific phase distribution. When the light exiting from the lens 4 irradiates on the modulation plate 5, the light will obtain different phase delays when passing through different positions of the modulation plate 5, thereby realizing the phase encoding of the light field. This modulation encodes the information of the light field into the distribution of the modulated light field, providing the necessary conditions for subsequent inversion of the optical parameters of the sample through the iterative algorithm.

[0039] The modulated light finally enters the data acquisition system 6. The data acquisition system 6 is a polarization camera that can simultaneously record the intensity information in four polarization directions of 0°, 45°, 90°, and 135°. The 0° direction is the same as the light passing direction of the polarizer 2. The polarization camera integrates detection units in multiple polarization directions. When the modulated light is incident on the camera, the light in different polarization directions will be received by the corresponding detection units and converted into corresponding electrical signals, thereby recording the intensity information of the diffraction spots in the four polarization directions. These intensity information contain the comprehensive information of the light field modulated by the sample and the modulation plate 5 and are the original data for subsequent data processing and parameter reconstruction.

[0040] The data processing system is connected to the data acquisition system 6 through a data line, processes the four polarization images collected by the data acquisition system 6, and reconstructs the amplitude, phase, and birefringence distribution maps of the sample to be measured 3 through an iterative algorithm. First, it receives the intensity data in four polarization directions from the data acquisition system 6, and then uses the polarization coherent modulation imaging algorithm for iterative calculation. During the iteration process, by continuously back-propagating the light field on the camera plane to the modulation plate 5 plane, removing the modulation of the modulation plate 5, and back-propagating to the focal plane and other operations, the light field distribution is gradually updated. Finally, the light field distribution at the focus is obtained and then back-propagated to the sample location, so as to obtain the amplitude and phase distributions of the sample in four polarization directions. Finally, according to the four-step phase-shift theory, the birefringence information of the sample is solved using the complex amplitude information in four polarization directions, including the angle between the polarizer 2 and the main axis of the stress point and the phase difference between the two beams of light, and then related parameters such as the principal stress difference are obtained.

[0041] Example Two

[0042] In the fields of laser processing and optical material research, the damage points generated in fused silica after laser irradiation will cause complex changes in the optical properties of the material, including the coupling of amplitude attenuation, phase delay, and birefringence effects. The single-exposure synchronous measurement of the damage point parameters is realized by using the device and method of the present invention.

[0043] This measurement device includes an illumination system 1, a polarizer 2, a sample to be measured 3, a lens 4, a modulation plate 5, and a data acquisition system 6. Among them, the illumination system 1 uses a helium-neon laser with a wavelength of 633 nm (output power 5 mW, coherence length > 20 cm), which is paired with a collimating lens 4 with a diameter of 50.8 mm and a focal length of 400 mm to intercept the light beam into a parallel coherent light with a diameter of 5 mm. The polarizer 2 selects a linear polarizer with a diameter of 50.8 mm, and the extinction ratio reaches 10000:1. The light transmission direction is set to the vertical direction to ensure the purity of the linearly polarized light. The sample to be measured 3 is fused silica glass (size 20 mm × 20 mm × 3 mm), and its surface is irradiated with a carbon dioxide laser and a nanosecond pulsed laser to form damage points. The diameter of the damage area is about 100 μm. The lens 4 selects an achromatic lens with a diameter of 25.4 mm, and the focal length f = 400 mm. The surface is coated with an anti-reflection film (transmittance at 633 nm wavelength > 99%) for focusing and diverging the light beam. The modulation plate 5 uses a sliced stem of a Chinese money tree as a phase-type modulation plate (size 10 mm × 10 mm), and its phase distribution is known and has a random phase characteristic for spatially modulating the illumination light. The data acquisition system 6 uses a four-channel polarization camera (resolution 1280 × 1024, pixel size 5.5 μm × 5.5 μm), and the light transmission directions are 0° (parallel to the polarizer 2), 45°, 90°, and 135° respectively, and is placed 200 mm behind the modulation plate 5. The data processing system processes the collected diffraction spots and reconstructs the amplitude, phase, and birefringence distribution maps of the sample to be measured 3 through an iterative algorithm.

[0044] Turn on the helium-neon laser and preheat it for 30 minutes until the power is stable (fluctuation < ±0.1%). Adjust the optical path through the aperture and mirrors to ensure that the coaxiality deviation between the beam and the optical axis of the system is < 0.05 mm. Use a power meter to rotate the polarizer 2. When the transmitted light intensity reaches the minimum value, fix the position. At this time, the light passing direction of the polarizer 2 is defined as 0°. Place the fused silica sample on the three-dimensional fine adjustment stage and adjust it so that the beam is perpendicularly incident on the center of the damage point. Place the lens 4 400 mm behind the sample. Confirm the focal position of the lens 4 by the focused spot method, with an error < 0.5 mm. Fix the modulation plate 5 50 mm behind the focal point of the lens 4 to ensure that the plane of the modulation plate 5 is perpendicular to the optical axis. The polarization camera is installed 200 mm behind the modulation plate 5. Ensure that the camera target plane is perpendicular to the optical axis through the leveling bracket, with an inclination < 0.5°.

[0045] Set the exposure time to 100 ms, the gain to 10 dB, and the trigger mode to single synchronous exposure to ensure that the four polarization channels are collected simultaneously. First, block the optical path to collect the dark noise image, and then use uniform diffused light to collect the flat field image for subsequent data preprocessing. Open the optical path, and the camera synchronously records the diffraction spot images in the four directions of 0°, 45°, 90°, and 135°. As Figure 2 shown, during the recording process, assume that the linearly polarized illumination light behind the polarizer 2 is , after passing through the sample it becomes elliptically polarized light, and then after passing through the lens 4 it is focused and irradiated onto the M(x, y) plane of the modulation plate 5. The modulation plate 5 is placed downstream of the focal point. One light passing direction of the polarization camera is parallel to the polarizer 2, and the angles are 0°, 45°, 90°, and 135° respectively. The collected diffraction spots are recorded as . The transmission process of the illumination light from the sample to the polarization camera is expressed as: , where, represents the light field distribution at the focal point, represents the light field distribution on the camera, is the transmission operator related to the focal length of the lens 4, is the focal length of the lens 4, is the transmission operator from the sample to the lens 4, represents the distance from the sample to the lens 4, is the transmission operator from the focal point to the modulation plate 5, is the distance from the focal point to the modulation plate 5, is the transmission operator from the modulation plate 5 to the camera, is the distance from the modulation plate 5 to the camera. After collection, view the spot symmetry in real time to ensure that there is no obvious deviation in the optical path.

[0046] Perform dark noise subtraction, flat-field correction, and Gaussian filtering on four images to eliminate speckle noise and background interference. Set the maximum number of iterations to 500 times, the relaxation factor = 0.7, the initial value of the aperture function R is 0.3 (linearly increasing to 1 with the number of iterations), the initial phase is set to 0, and represent the camera plane optical field as , where is the th iteration, the complex form of the camera plane optical field in the th polarization direction, is the amplitude of this optical field, is the phase of this optical field, replace the amplitude obtained with the intensity information recorded by the camera , where is the intensity information of the th iteration, the th polarization direction recorded by the camera, and transmit the updated optical field back to the encoding board surface , where is the optical field distribution transmitted back to the encoding board surface, is the back-propagation operator related to the distance from the modulation board 5 to the camera, remove the modulation of the modulation board 5 to obtain the incident light distribution on the surface of the modulation board 5 , where is the incident light distribution on the surface of the modulation board 5, is the complex conjugate of the phase function of the modulation board 5, is the maximum value of the square of the modulus of the phase function of the modulation board 5, is the focal plane optical field distribution of the th iteration, and transmit back to the focal plane, , where is the back-propagation operator related to the focal length of the lens 4, use the focal plane as a constraint to obtain the updated wavefront distribution of the focal plane , terminate the iteration when the root mean square error of the optical fields of adjacent iterations < 0.01, and actually converge at the 320th iteration.

[0047] Back-propagate the converged focal plane optical field to the sample plane, remove the lens 4 and the propagation phase, and obtain the complex amplitude of the transmission function of the sample in four polarization directions , where is the amplitude, is the phase.

[0048] Extract the squared amplitude values in four polarization directions , , , , and substitute them into the birefringence equations: , the included angle between the polarizer 2 and the stress principal axis is obtained by solving = 22.5° ± 0.3°, the phase difference = 1.2 rad ± 0.05 rad. According to the formula , where the stress-strain coefficient of fused silica = 3.1×10⁻¹² Pa⁻¹, the wavelength = 633 nm, the principal stress difference is calculated to be = 19.8 MPa ± 0.8 MPa.

[0049] The test results are used to generate a three-dimensional amplitude distribution map, a phase contour map, and a birefringence direction vector map. The amplitude attenuation in the central area of the damage point reaches 30%, the maximum phase delay is 1.8π, and the included angle between the birefringence principal axis direction and the laser incident direction is 23°, which is consistent with the theoretical expectation.

[0050] In summary, through the optical element multi-dimensional parameter single-exposure measurement device described in the present invention, the diffraction spots in four polarization directions are recorded by a single exposure of a polarization camera, and the polarization coherent coding imaging algorithm is used for calculation, so that the amplitude, phase, and birefringence distributions of the damage points produced by carbon dioxide laser and nanosecond pulsed laser in fused silica can be obtained.

[0051] The above is only a preferred embodiment of the present invention, and does not impose any form of limitation on the present invention. Although the present invention has been disclosed above with a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content within the scope of the technical solution of the present invention to make equivalent embodiments of equivalent changes. However, as long as the content of the technical solution of the present invention is not departed from, any brief modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. An optical element multi-dimensional parameter single-exposure measurement device, characterized in that The device includes the following components: a lighting system (1), a polarizer (2), a sample to be measured (3), a lens (4), a modulation plate (5), a data acquisition system (6), and a data processing system; The lighting system (1) consists of a coherent light source and a collimation system, providing a coherent illumination light beam with a diameter of about 5 mm for the system; The polarizer (2) is arranged behind the lighting system (1) and is used to convert the light beam into illumination light of a specific polarization state; The sample to be measured (3) is placed behind the polarizer (2); The lens (4) is placed behind the sample to be measured (3), first focusing and then diverging the illumination light; The modulation plate (5), placed behind the focal point, is used for modulating the illumination light; The data acquisition system (6) is arranged behind the modulation plate (5) and is used for acquiring diffraction spots; The data processing system is connected to the data acquisition system (6), processes the acquired diffraction spots, and reconstructs the amplitude, phase, and birefringence distribution maps of the sample to be measured (3) through an iterative algorithm.

2. The multi-dimensional parameter single-exposure measurement device for an optical element according to claim 1, characterized in that, The polarizer (2) is a linear polarizer with an extinction ratio of not less than 1000:

1.

3. The multi-dimensional parameter single-exposure measurement device for an optical element according to claim 1, characterized in that, The modulation plate (5) is a phase-type modulation plate.

4. An optical element multi-dimensional parameter single-exposure measurement device according to claim 1, characterized in that, The data acquisition system (6) is a polarization camera, which can simultaneously record the intensity information in four polarization directions. One of the light transmission directions is the same as the light transmission direction of the polarizer (2) and is arranged behind the modulation plate (5).

5. A method for measuring multi-dimensional parameters of an optical element by single exposure, which is applicable to the apparatus for measuring multi-dimensional parameters of an optical element by single exposure according to any one of claims 1-4, characterized in that, The method includes the following components: Optical path setting and initial light field preparation: The coherent light emitted by the lighting system (1) forms illumination light of a specific polarization state after passing through the polarizer (2) and irradiates the sample to be measured (3). The illumination light irradiating the sample to be measured (3) continues to propagate, is first focused and then diverged by the lens (4) placed behind the sample to be measured (3), and a phase-type modulation plate (5) with a known distribution is placed behind the focal point of the lens (4) for modulating the illumination light; Single-exposure data acquisition: The data acquisition system (6) records the modulated diffraction spots. The light transmission direction angles of the polarization camera are 0°, 45°, 90°, and 135° respectively, and four polarization images are acquired; Iterative reconstruction of the light field distribution: The four polarization images acquired by single-exposure are transmitted to the data processing system. The iterative algorithm is used to reconstruct the amplitude, phase, and birefringence distribution maps of the sample to be measured (3). The light field on the camera plane is expressed in complex form, the amplitude part in the complex form is replaced with the recorded intensity information, and the updated light field is transmitted along the direction opposite to the light propagation to the encoding plate surface to remove the modulation effect of the modulation plate (5) on the illumination light, obtaining the incident light distribution on the modulation plate (5) surface. The incident light distribution is reversely transmitted back to the focal plane, and with the focal plane as the constraint condition, the updated wavefront distribution of the focal plane is obtained; Calculation of birefringence information and determination of parameters: After multiple iterations, an accurate optical field distribution at the focal point is obtained. This optical field distribution is propagated backward to the lens (4), the phase influence of the lens (4) on the optical field is removed, and then it is continuously propagated backward to the sample. The amplitude and phase distributions of the transmission function of the sample in four polarization directions are obtained. Using the complex amplitude information in the four polarization directions, the birefringence information of the sample is solved, that is, the angle between the polarizer (2) and the principal axis X of the stress point and the phase difference between the two beams of light are determined. Through the calculation and analysis of relevant physical quantities, the principal stress difference is finally obtained.

6. The single-exposure measurement method for multi-dimensional parameters of an optical element according to claim 5, wherein In the single-exposure data acquisition step, the data acquisition system (6) records the modulated diffraction spot. During the recording process, assume that the linearly polarized illumination light after the polarizer (2) is After passing through the sample it becomes elliptically polarized light, and then passes through the lens (4) After focusing, it irradiates the M(x, y) plane of the modulation plate (5). The modulation plate (5) is placed downstream of the focus. One light-passing direction of the polarization camera is parallel to the polarizer (2), and the angles are 0°, 45°, 90°, and 135° respectively. The collected diffraction spots are denoted as The transmission process of the illumination light from the sample to the polarization camera is expressed as: where, represents the light field distribution at the focus, represents the light field distribution on the camera, is the transmission operator related to the focal length of the lens (4), is the focal length of the lens (4), is the transmission operator from the sample to the lens (4), represents the distance from the sample to the lens (4), is the transmission operator from the focus to the modulation plate (5), is the distance from the focus to the modulation plate (5), is the transmission operator from the modulation plate (5) to the camera, is the distance from the modulation plate (5) to the camera.

7. A method for measuring multi-dimensional parameters of an optical element by single-exposure, according to claim 5, characterized in that In the step of iteratively reconstructing the light field distribution, an iterative algorithm is used to reconstruct the amplitude, phase, and birefringence distribution maps of the sample to be measured (3). Specifically, in the th iteration, the light field on the camera plane is written in complex form, i.e., , where is the complex form of the light field on the camera plane in the th iteration and the th polarization direction, is the amplitude of this light field, is the phase of this light field, and the amplitude is replaced with the intensity information recorded by the camera, where is the intensity information of the th iteration and the th polarization direction recorded by the camera. The updated light field is reversely transmitted to the encoding board surface , where is the light field distribution reversely transmitted to the encoding board surface, is the reverse transmission operator related to the distance from the modulation board (5) to the camera. The modulation of the modulation board (5) is removed to obtain the incident light distribution on the surface of the modulation board (5), where is the incident light distribution on the surface of the modulation board (5), is the complex conjugate of the phase function of the modulation board (5), is the maximum value of the square of the modulus of the phase function of the modulation board (5), is the light field distribution on the focal plane in the th iteration. is reversely transmitted back to the focal plane, , where is the reverse transmission operator related to the focal length of the lens (4). Using the focal plane as a constraint, the updated wavefront distribution on the focal plane is obtained, where is the wavefront distribution on the focal plane in the th iteration, R is the aperture function that changes with the number of iterations, and the relaxation factor . The iteration is repeated to obtain the light field distribution at the focus, which is reversely transmitted back to the lens (4), the phase of the lens (4) is removed, and then it is reversely transmitted back to the sample to obtain the transmission function of the sample in the amplitude and phase distributions in four polarization directions, i.e., .

8. The method for measuring multi-dimensional parameters of an optical element by single-exposure according to claim 5, characterized in that, In the step of calculating the birefringence information and determining the parameters, the birefringence information of the sample is solved by using the complex amplitudes in four polarization directions, that is, the angle between the polarizer (2) and the main axis of the stress point is solved , and the phase difference between the two beams of light . The calculation formula is: , where is the amplitude in different polarization directions is the amplitude parameter related to the birefringence of the sample, representing the initial amplitude component not affected by birefringence. is the angle between the light passing direction of the polarizer (2) and the main axis of the stress point of the sample , which is used to characterize the direction characteristics of birefringence. is the phase difference between two orthogonally polarized light beams in the sample, reflecting the intensity of birefringence. Solving the equations gives . Substituting into , we get an expression of independent of . Further, the principal stress difference is obtained, where , and are the principal stresses in two perpendicular directions at the stress point, is the wavelength of the illumination light, is the reduced Planck constant, is the stress-strain coefficient of the sample, which is used to characterize the conversion relationship between stress and birefringence.

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