Amplitude, Phase, and Polarization Characterization Method and Device Based on Coherent Diffraction Imaging

Abstract

The present invention discloses a method and apparatus for amplitude, phase, and polarization characterization based on coherent diffraction imaging. The method uses a specially designed phase diagram to modulate the field to be measured, and uses a phase reconstruction method based on coherent diffraction imaging to separately measure and reconstruct the complex amplitudes of the 0°, 45°, and 90° direction components of the field to be measured. And by using the relationship between the complex amplitudes of the three polarization direction components, the correct relationship between the phases of a pair of 0° and 90° complex amplitude recovery results is reconstructed, so as to complete the characterization of the amplitude, phase, and polarization of the field to be measured. This method does not have the thin sample assumption, can detect samples sensitive to the incident direction, and because it is based on coherent diffraction imaging rather than the interference method, it has a simple structure and the potential for miniaturization.

Description

Technical Field

[0001] The present invention relates to optical imaging, coherent diffraction imaging, phase retrieval, and polarization measurement, and particularly to a method and apparatus for characterizing amplitude, phase, and polarization based on coherent diffraction imaging, which can be used for measuring the phase and polarization characteristics of devices such as micro-nano devices, metasurfaces, biological samples, phase gratings, and diffractive optical elements. Background Art

[0002] Phase characterization methods are mainly divided into the interference method and the diffraction method. Among them, the interference method uses the interference effect of light to characterize the phase. This method can characterize the target phase with high resolution, but the disadvantage is that the optical path is complex, the requirements for the optical path difference between the reference arm and the measurement arm are very high, and it does not have the potential for miniaturization.

[0003] The diffraction method is another common phase characterization method, which uses the diffraction propagation theory of light to calculate the phase of the light wave. The diffraction method is usually based on the iterative phase retrieval algorithm, which enables the calculation of the phase distribution of the entrance pupil plane by adding constraints and iterative calculations in the case of only the amplitude of the image plane. Therefore, based on the diffraction method, the phase and amplitude of the incident light wave can be measured simultaneously. The more representative methods are Fourier ptychography and coherent diffraction imaging.

[0004] Fourier ptychography generates wide-field, high-resolution complex sample images by iteratively stitching multiple low-resolution, variable illumination intensity images in the Fourier space. This imaging method transforms the challenges of high-throughput, high-resolution microscopy from problems related to the physical limitations of the system optics into computational problems. Fourier ptychography can achieve very high resolution even with a low-resolution microscope, but due to multi-angle illumination, the premise of using it is that the sample must conform to the thin sample hypothesis. This also limits the range of samples that Fourier ptychography can detect. It also faces problems such as a complex system, the need to capture multiple images, and a relatively long time for capturing and reconstruction.

[0005] Coherent diffraction imaging is an imaging technique based on the coherent diffraction principle of an object and an optical system. Coherent light diffracts after passing through the object to form the diffraction pattern of the object, and then is imaged onto the detection plane through an optical system (such as a lens). This method enables the calculation of the phase distribution of the entrance pupil plane based on the iterative phase retrieval algorithm in the case of only the amplitude of the image plane. The calculation results of coherent diffraction imaging contain the amplitude and phase information of the object and can be used for three-dimensional reconstruction and digital reconstruction. It has wide applications in the fields of biomedicine, materials science, etc. The advantage of this method is that the optical path is simple and relatively high resolution can also be obtained.

[0006] For some samples with polarization characteristics, such as micro-nano devices, phase gratings, etc., they are often sensitive to the direction and polarization state of incident light, and at the same time, they will also modulate the polarization state of incident light. When characterizing these devices, not only should we focus on their modulation capabilities for amplitude and phase, but also on their modulation of polarization. Currently, there are some methods for simultaneously characterizing phase and polarization state, such as the polarization and phase characterization method based on the interference method, which faces problems such as complex systems and difficulty in miniaturization, and cannot characterize amplitude; while the polarization and phase characterization method based on Fourier ptychography microscopy, due to the need to irradiate the sample with incident light in different directions, has the assumption of thin samples for the sample, and this method also cannot characterize those samples that are sensitive to the incident light direction.

[0007] In summary, in the prior art, there is a lack of a characterization method that can simultaneously characterize amplitude, phase, and polarization with high resolution and also has the potential for miniaturization. Summary of the Invention

[0008] The object of the present invention is to provide a method and device for characterizing amplitude, phase, and polarization based on coherent diffractive imaging in view of the deficiencies of the prior art. This method measures the three polarization direction components respectively and performs phase reconstruction, and completes the characterization of the amplitude, phase, and polarization of the light field to be measured by reconstructing the correct relative relationship between the phases of a pair of orthogonal complex amplitudes. This method does not have the thin sample assumption, can detect samples sensitive to the incident direction, and because it is based on coherent diffractive imaging rather than the interference method, it has a simple structure and the potential for miniaturization.

[0009] The object of the present invention is achieved by the following technical solutions:

[0010] According to the first aspect of this specification, a method for characterizing amplitude, phase, and polarization based on coherent diffractive imaging is provided, and the method includes:

[0011] Irradiate the sample to be measured with monochromatic parallel light, and sequentially place a rotatable half-wave plate, a liquid crystal spatial light modulator, a lens, and an image detector behind the sample;

[0012] Load a designed phase diagram on the spatial light modulator, and decompose the phase diagram into 4 complex amplitude filters;

[0013] Take intensity images at the angles of 0°, 22.5°, and 45° of the half-wave plate respectively, and then be modulated by the phase diagram loaded on the spatial light modulator to form 4 modulated first-order diffraction spots on the image detector plane, and then perform image segmentation to obtain 4 spot images containing only the spots on a single first-order diffraction order;

[0014] Based on four complex amplitude filters and the four spot images obtained by segmentation, the iterative phase retrieval algorithm is used to retrieve the complex amplitudes of the 0°, 45°, and 90° components of the optical field to be measured respectively;

[0015] Utilize the relationships between the amplitudes and phases of the 0°, 45°, and 90° components of the optical field to be measured to retrieve the polarization state of the optical field to be measured.

[0016] Further, define the liquid crystal polarization direction of the spatial light modulator as 0°. The half-wave plate is used to rotate the polarization direction of the incident light, which needs to be rotated to three angles respectively, namely 0°, 22.5°, and 45°. These three angles respectively correspond to the spatial light modulator modulating the 0°, 45°, and 90° polarization direction components of the optical field to be measured.

[0017] Further, a designed phase map is loaded on the spatial light modulator, such that while the modulated incident light is diffracted to four first-order diffraction orders around the zero order, it is randomly modulated differently at each first-order diffraction order. The light of these four first-order diffraction orders is focused by a lens on an image detector to form four spots, and the intensity information is recorded by the image detector.

[0018] Further, the design method of the phase map loaded on the spatial light modulator is as follows:

[0019] Generate four random phase maps on the plane of the spatial light modulator, and respectively calculate the spots formed on the image detector after the light modulated by each random phase map passes through the lens using the diffraction propagation theory;

[0020] Cut the central parts of the four spots to obtain four cut spot images, and then place them on the four first-order diffraction orders of a blank image on the plane of the image detector respectively, and splice them into one image;

[0021] Using the iterative phase retrieval algorithm, back-calculate the spliced image to the plane of the spatial light modulator, and retrieve and obtain one phase map under the constraint condition of pure phase, and load it on the spatial light modulator.

[0022] Further, back-calculate the four spot images each containing only a single first-order diffraction order to the plane of the spatial light modulator using the iterative phase retrieval algorithm to obtain four complex amplitude images. Regard these four complex amplitude images as four complex amplitude filters obtained by decomposing the phase map loaded on the spatial light modulator; Modulate the incident field using these four complex amplitude filters respectively, and four corresponding spots on the four first-order diffraction orders will be generated respectively.

[0023] Further, the specific method for retrieving the complex amplitude is as follows:

[0024] Load the designed phase diagram onto the spatial light modulator, and capture an image that has been modulated by the spatial light modulator once through an image detector. Decompose this image into 4 spot images that only contain the light spots on a single first-order diffraction order, and regard these 4 spot images as the results of being modulated by 4 complex amplitude filters respectively;

[0025] Use the iterative phase retrieval algorithm to separately retrieve the phase and amplitude of the optical field to be measured by using these 4 spot images and their corresponding 4 complex amplitude filters. Finally, average the four retrieval results to obtain the complex amplitude of the optical field to be measured.

[0026] Furthermore, the specific method for retrieving polarization is as follows:

[0027] Rotate the half-wave plate to 0°, 22.5°, and 45° respectively, and retrieve the complex amplitudes of 0°, 45°, and 90° of the optical field to be measured;

[0028] The polarization state of the optical field to be measured E is represented by the Jones vector, as shown in Equation (1):

[0029]

[0030] where E x , E y are the complex amplitudes of 0° and 90° obtained through complex amplitude retrieval respectively, E x0 , E y0 are the amplitudes in the polarization directions of 0° and 90° respectively, are the phases in the polarization directions of 0° and 90° respectively, and the phase difference

[0031] Solve the phase offset constant according to the measurement result of the 45° complex amplitude;

[0032]

[0033] where E 45 is the 45° complex amplitude obtained through complex amplitude retrieval, are the phase offset constants in the phase retrieval results of 0°, 45°, and 90° respectively; let Derive according to Equation (2):

[0034]

[0035] Use linear search to obtain the

[0036]

[0037] Substitute the obtained into Equation (2) to obtain the Jones vector of the optical field to be measured, as shown in Equation (1).

[0038] According to a second aspect of the present specification, there is provided an amplitude, phase, and polarization characterization device based on coherent diffraction imaging. The device includes a half-wave plate, a liquid crystal spatial light modulator, a lens, an image detector, a complex amplitude recovery module, and a polarization state recovery module, which are sequentially placed behind the sample to be measured;

[0039] A monochromatic parallel light is used to irradiate the sample to be measured, and a rotatable half-wave plate is placed behind the sample to select the direction of the polarization component to be detected; subsequently, a liquid crystal spatial light modulator loaded with a designed phase diagram is placed to perform phase encoding on the incident light; a lens is placed behind the spatial light modulator to focus the light spot on the image detector plane;

[0040] The complex amplitude recovery module is used to segment the light spot images captured by the image detector and decomposed onto 4 first-order diffraction orders, respectively obtaining 4 light spot images each containing only a single first-order diffraction order. Based on the 4 segmented light spot images and their corresponding complex amplitude filters, the complex amplitudes of the 0°, 45°, and 90° components of the light field to be measured are respectively recovered using an iterative phase recovery algorithm;

[0041] The polarization state recovery module uses the relationship between the amplitudes and phases of the 0°, 45°, and 90° components of the light field to be measured to recover the polarization state of the light field to be measured.

[0042] Compared with the prior art, the present invention has the following beneficial technical effects:

[0043] 1. The spatial light modulator directly diffracts the incident light to orders other than 0°, avoiding the interference of the unmodulated incident light.

[0044] 2. For a single polarization direction, only a single phase diagram needs to be loaded and a single shot is required to recover the complex amplitude of the light field to be measured.

[0045] 3. Utilize the 45° complex amplitude recovery result to reconstruct the correct phase relationship between the 0° and 90° complex amplitude recovery results.

[0046] 4. Simultaneously detect the phase, amplitude, and polarization in a non-interferometric manner, with strong anti-interference ability, simple structure, and potential for miniaturization. Description of the Drawings

[0047] Figure 1 is a schematic diagram of the optical path structure of the present invention;

[0048] Figure 2 is the designed phase diagram loaded on the spatial light modulator;

[0049] Figure 3 is a schematic diagram of the speckle image after removing the central light spot captured by the image detector;

[0050] Figure 4 It is a schematic diagram of a speckle image obtained by cutting and splicing the central part of four light spots modulated by random phase diagrams.

[0051] Figure 5 It is a schematic diagram of four light spot images after decomposition, each containing only a single first-order diffraction order.

[0052] Figure 6 It is a flow chart of the method of the present invention. Detailed implementation manners

[0053] The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited thereto.

[0054] The present invention provides a method for characterizing amplitude, phase, and polarization based on coherent diffraction imaging. As Figure 1 shown, the following optical path structure is adopted: A monochromatic parallel light is used to irradiate the sample to be measured, and the outgoing light field of the sample is the light field E to be measured. A rotatable half-wave plate is placed at the outgoing end of the sample to select the direction of the polarization component to be detected. Subsequently, a liquid crystal spatial light modulator is placed to perform phase encoding on the incident light. A lens is placed behind the spatial light modulator to focus the light spot on the image detector plane. The image detector captures an intensity image and uses this intensity image to iteratively calculate the amplitude, phase, and polarization of the sample.

[0055] In this embodiment, the spatial light modulator is a transmissive liquid crystal, so only a specific linear polarization direction will be modulated by the spatial light modulator. Here, the liquid crystal polarization direction of the spatial light modulator is defined as 0°. The half-wave plate is used to rotate the polarization direction of the incident light, and it needs to be rotated to three angles respectively, namely 0°, 22.5°, and 45°. These three angles respectively correspond to the spatial light modulator modulating the 0°, 45°, and 90° polarization direction components of the light field E to be measured. A designed phase diagram needs to be loaded on the spatial light modulator. As Figure 2 shown, while the modulated incident light is diffracted to the four first-order diffraction orders around the 0th order, it will also be randomly modulated differently on each first-order diffraction order. Then the light of these four first-order diffraction orders will be focused on the image detector by the lens to form four light spots, and the intensity information will be recorded by the image detector. The incident light orthogonal to the polarization direction of the spatial light modulator will not be modulated by the spatial light modulator, so it will be directly focused on the center through the lens to form a light spot. This light spot can be directly filtered out by cutting the image during the later algorithm processing. The filtering effect is as Figure 3 shown.

[0056] A designed phase map is loaded on the spatial light modulator, which can diffract the incident light into four first-order diffraction orders around the 0th order. At the same time, each first-order diffraction order will be randomly modulated differently. The design method of the spatial light modulator is described below.

[0057] First, four random phase images are generated on the plane of the spatial light modulator, and the light spots formed on the image detector after the light modulated by each random phase image passes through the lens are calculated using the diffraction propagation theory. The central part of the four light spots, that is, the part with the most concentrated brightness, is cut, for example, the part with a central side length of l' is cut to obtain four cut light spot images, and then they are placed on the four first-order diffraction orders of a blank image on the plane of the image detector, and spliced ​​into an image, such as Figure 4 As shown, D is the side length of the image detector, and the values ​​of l and l' can be adjusted according to the phase recovery effect. In this embodiment, l = 0.2D, l' = 0.25D. Using the iterative phase recovery algorithm, the image is back-calculated back to the spatial light modulator plane, and a phase image is recovered under the pure phase constraint, as shown in Figure 2 As shown in the figure, this image is the phase image loaded on the spatial light modulator. After being modulated by this phase image, the spot image captured by the detector is as follows Figure 3 As shown. This achieves the diffraction of the incident light into four first-order diffraction orders around the 0th order, while also performing different random modulations on each first-order diffraction order.

[0058] Figure 3 It can be further decomposed into four images containing only the spot image of a single 1st diffraction order, such as Figure 5 As shown. These four images are back-calculated back to the spatial light modulator plane using an iterative phase recovery algorithm to obtain four complex amplitude images. These four complex amplitude images can be regarded as four complex amplitude filters obtained by decomposing the phase image loaded on the spatial light modulator. Using these four complex amplitude filters to modulate the incident field will generate four corresponding light spots on the first diffraction order.

[0059] The complex amplitude recovery method is described below. Figure 2 The phase image shown is loaded on the spatial light modulator. By taking an image modulated by the spatial light modulator once with an image detector, the image can be further decomposed into four images containing only the spot image on a single 1st diffraction order, such as Figure 5 These four spot images can be regarded as the results of modulation of four complex amplitude filters, so one pure phase modulation can achieve the effect of shooting four images. Using the iterative phase recovery algorithm, the four images and their corresponding four complex amplitude filters can be used to recover the phase and amplitude of the light field to be measured, and finally the four recovery results are averaged to obtain the final complex amplitude of the light field to be measured.

[0060] The polarization recovery method is described below. By taking three speckle images at 0°, 45°, and 90° obtained by rotating a half-wave plate, the amplitude and phase of the incident field at 0°, 45°, and 90° can be respectively recovered using the above complex amplitude recovery method.

[0061] The polarization state of the optical field E to be measured can be represented by a Jones vector, as shown in Equation (1):

[0062]

[0063] where E x , E y are the complex amplitudes at 0° and 90° respectively obtained through complex amplitude recovery, E x0 , E y0 are the amplitudes in the polarization directions of 0 and 90° respectively, are the phases in the polarization directions of 0 and 90° respectively, and the phase difference As long as the amplitudes and phases at 0° and 90° are obtained, the polarization state of the optical field to be measured can be obtained. However, there is a global phase shift in the phase recovery result of the iterative phase recovery algorithm, that is, the recovered phase will be superimposed with a global and random phase shift constant. It is necessary to introduce the measurement result of the complex amplitude at 45° to solve the phase shift constant.

[0064]

[0065] where E x , E y , E 45 are the complex amplitudes at 0°, 45°, and 90° respectively obtained through complex amplitude recovery, are the phase shift constants in the phase recovery results at 0°, 45°, and 90° respectively. Since we only need to solve the correct phase difference between E x , E y instead of the absolute value of the phase of a single polarization direction component, we can set Then we only need to solve

[0066] According to Equation (2), it can be derived that:

[0067]

[0068] Each corresponding pixel in E x , E y , E 45 needs to satisfy Equation (3), and is just a constant with a value range of [0, 2π). Therefore, a linear search can be used to find the

[0069]

[0070] Substitute the obtained into Equation (2), then the phase shift between the complex amplitude recovery results at 0° and 90° can be eliminated, and the Jones vector of the optical field to be measured can be obtained, as shown in Equation (1).

[0071] In summary, as Figure 6 shown, the overall shooting and image processing flow of the method of the present invention is as follows:

[0072] The light beam is modulated by the designed phase pattern loaded on the spatial light modulator and then decomposed into four first-order diffraction orders. After being focused by a lens, the image detector finally captures the spot images decomposed into four first-order diffraction orders; the images are segmented to obtain four spot images each containing only a single first-order diffraction order.

[0073] Load the designed phase pattern on the spatial light modulator and decompose the phase pattern into four complex amplitude filters.

[0074] Use the iterative phase retrieval algorithm to separately retrieve the phase and amplitude of the optical field to be measured by using these four segmented spot images and their corresponding complex amplitude filters. After summing and averaging the four complex amplitudes of the optical field to be measured, the complex amplitude distribution of the 0° component of the optical field to be measured can be obtained.

[0075] Repeat the above steps to retrieve the complex amplitudes of the 0°, 45°, and 90° components of the optical field to be measured, which are represented by E x , E y , and E 45 respectively.

[0076] Since the phase retrieved by the iterative phase retrieval algorithm will be superimposed with a global and random phase shift constant. Define as the phase shift constants in the phase retrieval results at 0°, 45°, and 90° respectively. Let Then, only by solving can the relative phase inaccuracy between E x and E y be eliminated.

[0077] Substitute E x , E y , and E 45 into Equation (4), and use the linear search method to find when Equation (4) is minimized. Substitute into Equation (2), then the Jones vector of the optical field to be measured can be obtained.

[0078] Thus, the characterization of the phase, amplitude, and polarization of the optical field to be measured is completed.

[0079] Based on coherent diffraction imaging, the present invention designs a single-phase diagram that can be decomposed into four complex amplitude filters, and the complex amplitude of the optical field to be measured can be reconstructed through a single shot. On this basis, using the polarization characteristics of a half-wave plate and a liquid crystal spatial light modulator, the three polarization direction components of the optical field to be measured are measured, and the polarization state of the optical field to be measured can be restored. Thus, the measurement of the amplitude, phase, and polarization of the optical field to be measured is completed.

[0080] Corresponding to the above embodiments of the amplitude, phase, and polarization characterization method based on coherent diffraction imaging, the present invention also provides embodiments of an amplitude, phase, and polarization characterization device based on coherent diffraction imaging. The device based on the method of the present invention includes a half-wave plate, a liquid crystal spatial light modulator, a lens, an image detector, a complex amplitude recovery module, and a polarization state recovery module, which are sequentially placed behind the sample to be measured.

[0081] Specifically, a monochromatic parallel light is used to irradiate the sample to be measured, and a rotatable half-wave plate is placed at the exit end of the sample to select the direction of the polarization component to be detected. Subsequently, a liquid crystal spatial light modulator loaded with a designed phase diagram is placed to perform phase encoding on the incident light. A lens is placed behind the spatial light modulator to focus the light spot on the image detector plane. The image detector captures the intensity image.

[0082] The complex amplitude recovery module is used to segment the light spot images captured by the image detector and decomposed onto four first-order diffraction orders, respectively obtaining four light spot images each containing only a single first-order diffraction order. Based on the four segmented light spot images and their corresponding complex amplitude filters, the iterative phase recovery algorithm is used to respectively restore the amplitude and phase of the 0°, 45°, and 90° components of the optical field to be measured.

[0083] The polarization state recovery module uses the relationship between the amplitudes and phases of the 0°, 45°, and 90° components of the optical field to be measured to restore the polarization state of the optical field to be measured.

[0084] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather will be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for characterizing amplitude, phase, and polarization based on coherent diffraction imaging, characterized in that: include: Use monochromatic parallel light to illuminate the sample to be tested, and place a rotatable 1 / 2 wave plate, a liquid crystal spatial light modulator, a lens and an image detector in sequence behind the sample; A designed phase map is loaded on the spatial light modulator, and the phase map is decomposed into four complex amplitude filters; The intensity images are taken when the angles of the 1 / 2 wave plate are 0°, 22.5°, and 45°, respectively, and then modulated by the phase image loaded on the spatial light modulator to form four modulated first-order diffraction spots on the image detector plane. After that, the image is segmented to obtain four spot images containing only a single first-order diffraction order. Based on 4 complex amplitude filters and 4 spot images obtained by segmentation, the iterative phase recovery algorithm is used to recover the complex amplitudes of the 0°, 45°, and 90° components of the measured light field respectively. The relationship between the amplitude and phase of the 0°, 45°, and 90° components of the light field to be measured is used to restore the polarization state of the light field to be measured. The specific method for recovering the polarization is as follows: Rotate the 1 / 2 wave plate to 0°, 22.5°, and 45° to restore the complex amplitudes of the light field to be measured at 0°, 45°, and 90° respectively; The polarization state of the light field E to be measured is represented by the Jones vector, as shown in formula (1): Among them, E x 、E y are the complex amplitudes of 0° and 90° obtained after complex amplitude recovery, E x0 、E y0 are the amplitudes in the 0° and 90° polarization directions, They are the phases in the 0 and 90° polarization directions, and the phase difference Solve the phase shift constant based on the 45° complex amplitude measurement result; Among them, E 45 is the 45° complex amplitude obtained after complex amplitude recovery, are the phase shift constants in the phase recovery results of 0°, 45°, and 90° respectively; According to formula (2), we can deduce: Use linear search to find the minimum solution of formula (4) Will be obtained Substituting into equation (2), the Jones vector of the light field to be measured is obtained, as shown in equation (1).

2. The amplitude, phase, and polarization characterization method based on coherent diffraction imaging according to claim 1, characterized in that: The liquid crystal polarization direction of the spatial light modulator is defined as 0°. The 1 / 2 wave plate is used to rotate the polarization direction of the incident light. It needs to be rotated to three angles, namely 0°, 22.5° and 45°. These three angles correspond to the spatial light modulator modulating the 0°, 45° and 90° polarization direction components of the measured light field.

3. The amplitude, phase, and polarization characterization method based on coherent diffraction imaging according to claim 1, characterized in that: The spatial light modulator is loaded with a designed phase diagram, so that the modulated incident light is diffracted to four first-order diffraction orders around the 0th order, and at the same time, is subjected to different random modulations at each first-order diffraction order. The light of the four first-order diffraction orders is focused by the lens onto the image detector to form four light spots, and the intensity information is recorded by the image detector.

4. The amplitude, phase, and polarization characterization method based on coherent diffraction imaging according to claim 1, characterized in that: The design method of the phase pattern loaded on the spatial light modulator is as follows: Generate 4 random phase images located on the plane of the spatial light modulator, and use the diffraction propagation theory to calculate the light spots formed on the image detector after the light modulated by each random phase image passes through the lens; Cut the central parts of the four light spots to obtain four cut light spot images, and then place them respectively on the four first-order diffraction orders of the blank image located on the image detector plane to splice them into one image; The spliced ​​image is back-calculated to the spatial light modulator plane using an iterative phase recovery algorithm. Under the constraint of pure phase, a phase map is recovered and loaded on the spatial light modulator.

5. The amplitude, phase, and polarization characterization method based on coherent diffraction imaging according to claim 1, characterized in that: The four images of the spot light only containing the single first-order diffraction are back-calculated to the spatial light modulator plane by using an iterative phase recovery algorithm to obtain four complex amplitude images. The four complex amplitude images are regarded as four complex amplitude filters obtained by decomposing the phase map loaded on the spatial light modulator; Using these four complex amplitude filters to modulate the incident field will generate corresponding light spots on the four first-order diffraction orders respectively.

6. The amplitude, phase, and polarization characterization method based on coherent diffraction imaging according to claim 1, characterized in that: The complex amplitude recovery method is specifically as follows: The designed phase map is loaded on the spatial light modulator, and the image modulated by the spatial light modulator is captured by the image detector, and the image is decomposed into four spot images containing only a single first-order diffraction order. These four spot images are regarded as the results of modulation of four complex amplitude filters respectively. Using an iterative phase recovery algorithm, the four spot images and their corresponding four complex amplitude filters are used to recover the phase and amplitude of the light field to be measured. Finally, the four recovery results are averaged to obtain the final complex amplitude of the light field to be measured.

7. An amplitude, phase, and polarization characterization device implemented based on the method according to any one of claims 1 to 6, characterized in that: The device comprises a 1 / 2 wave plate, a liquid crystal spatial light modulator, a lens, an image detector, a complex amplitude recovery module and a polarization state recovery module which are sequentially placed behind the sample to be tested; Use monochromatic parallel light to illuminate the sample to be tested, and place a rotatable 1 / 2 wave plate behind the sample to select the direction of the polarization component to be detected; then place a liquid crystal spatial light modulator loaded with a designed phase diagram to perform phase encoding on the incident light; and place a lens behind the spatial light modulator to focus the light spot on the image detector plane. The complex amplitude recovery module is used to segment the spot image captured by the image detector and decomposed into four first-order diffraction orders, respectively obtaining four spot images containing only a single first-order diffraction order, and based on the four segmented spot images and their corresponding complex amplitude filters, using an iterative phase recovery algorithm to respectively recover the complex amplitudes of the 0°, 45°, and 90° components of the light field to be measured; The polarization state recovery module recovers the polarization state of the light field to be measured by using the relationship between the amplitude and phase of the 0°, 45°, and 90° components of the light field to be measured.

Images