A diffraction-based light field imaging method and system

Abstract

The application discloses a kind of based on diffraction's light field imaging method and system, comprising: set up including having axial chromatic aberration lens, diffraction grating and image sensor's imaging device;Using imaging device to the point light source on optical axis imaging, move point light source adjustment its distance to have axial chromatic aberration lens let the imaging result of point light source have minimum dispersion circle on image sensor plane, capture the focused imaging image of point light source and calibration obtain the distance of diffraction grating to image sensor;According to the distance of diffraction grating to image sensor and the diffraction efficiency of diffraction grating obtained, the optical coding response of each wavelength corresponding focusing plane image is calculated;Using imaging device to the scene meeting the condition under multi-wavelength environment imaging, the data of image sensor and optical coding response are substituted into optimization model calculation reconstruction to obtain all focusing plane images;The application can realize the single exposure acquisition of multiple focusing plane light field, complete dynamic scene light field acquisition.

Description

A diffraction-based light field imaging method and system Technical Field

[0001] This invention relates to the fields of computer vision and digital image processing technology, and in particular to a diffraction-based light field imaging method and system. Background Technology

[0002] A light field is a complete set of light distributions in space. Traditional cameras project the light field onto a two-dimensional sensor plane, losing the rich information contained within it, thus limiting their application. Researching methods for acquiring light field data and obtaining complex and ever-changing high-dimensional information from dynamic scenes can promote the development of many fields such as life sciences and holographic displays. Multi-focus plane light fields consist of a series of images focused at different depths of the scene. These light fields are obtained by changing the position of the focusing plane of the imaging device and have already been applied in tasks such as depth estimation, extended depth of field, and viewpoint synthesis. Existing multi-focus plane light field acquisition methods can be divided into two categories: the first, mechanically controlled methods, typically use a translation stage to move the camera along the optical axis or manually rotate the camera's zoom ring; the second, electrically tunable optical methods, typically introduce spatial light modulators or liquid crystal lenses into the imaging device. Both of these methods require sequential scanning of multiple focusing planes, making them unsuitable for acquiring light fields in dynamic scenes.

[0003] It should be noted that the information disclosed in the background section mentioned above is for the purpose of understanding the relevant background of this invention only, and therefore may cover prior art information known to those not skilled in the art. Therefore, we should not use the aforementioned background information as a standard for evaluating the novelty and inventiveness of this invention. Summary of the Invention

[0004] To address the technical problem that existing multi-focus plane light field imaging methods cannot simultaneously capture multiple focus plane images in a single exposure and are not suitable for acquiring light fields in dynamic scenes, the primary objective of this invention is to provide a diffraction-based light field imaging method.

[0005] Another object of the present invention is to provide a system including the above-described diffraction-based light field imaging method.

[0006] Another object of the present invention is to provide a computer-readable medium comprising the above-described diffraction-based light field imaging method.

[0007] This invention is achieved through the following technical solution:

[0008] A diffraction-based light field imaging method includes the following steps: S1: Constructing an imaging device including a lens with axial chromatic aberration, a diffraction grating, and an image sensor; S2: Using the imaging device to image a point light source located on the optical axis, moving the point light source to adjust its distance from the lens with axial chromatic aberration so that the imaging result of the point light source has the smallest circle of confusion on the image sensor plane, capturing the focused imaging image of the point light source, and calibrating the distance from the diffraction grating to the image sensor; S3: Calculating the optical coding response of the focal plane image corresponding to each wavelength based on the calibrated distance from the diffraction grating to the image sensor and the diffraction efficiency of the diffraction grating; S4: Using the imaging device to image a scene that meets the conditions in a multi-wavelength environment, substituting the data from the image sensor and the optical coding response into an optimization model to reconstruct all focal plane images.

[0009] In some embodiments of the present invention, in step S1, the lens with axial chromatic aberration is used to provide the imaging device with a focal length that varies with wavelength; the diffraction grating is used to provide the imaging device with an optically encoded response that varies with wavelength; the image sensor is used to record multiple optically encoded images of the focal plane; the image sensor is selected from a CMOS sensor or a CCD sensor; the lens with axial chromatic aberration, the diffraction grating, and the image sensor are placed parallel to each other along the optical axis.

[0010] In some embodiments of the present invention, step S2, in which the calibration is performed to obtain the distance from the diffraction grating to the image sensor, includes the following steps:

[0011] S2-1. Binarize the focused imaging image;

[0012] S2-2, Obtain the centroid position of the connected components in the binarized focused imaging image;

[0013] S2-3. Calculate the centroid spacing of the connected regions between adjacent diffraction image points in the horizontal and vertical directions, respectively.

[0014] S2-4. Calculate the distance from the diffraction grating to the image sensor based on the centroid spacing, using the following expression:

[0015]

[0016] Where z represents the distance from the diffraction grating to the image sensor, h represents the horizontal direction, v represents the vertical direction, and λ p The wavelength d represents the point light source. h d represents the period of the diffraction grating along the horizontal direction. v This represents the period of the diffraction grating along the vertical direction. The centroid spacing in the horizontal direction represents the connected domains between adjacent diffraction image points in the i-th group. denoted by , represents the centroid spacing of the connected domains between adjacent diffraction image points in the j-th group in the vertical direction, K represents the number of centroid spacings in the horizontal direction, and L represents the number of centroid spacings in the vertical direction.

[0017] In some embodiments of the present invention, in step S3, the expression for calculating the optical coded response of the focal plane image corresponding to each wavelength is as follows:

[0018]

[0019] Where x represents the horizontal coordinate value, y represents the vertical coordinate value, and λ a Represents wavelength, h G (x,y;λ a ) represents wavelength λ a The corresponding optically encoded response of the focused plane image, where m represents the diffraction order of the diffraction grating in the horizontal direction, n represents the diffraction order of the diffraction grating in the vertical direction, |C m,n (λ a )| 2 The diffraction grating represents the wavelength λ. a The diffraction efficiency of the (m,n)th order diffraction order, where δ(·) represents the unit impulse function, and x0 = λ a z / d h y0 = λ represents the distance interval between adjacent impulse functions in the horizontal direction. a z / d v The z and d represent the distance interval between adjacent impulse functions in the vertical direction. h and d v These are the distance from the diffraction grating to the image sensor, the period of the diffraction grating along the horizontal direction, and the period of the diffraction grating along the vertical direction, respectively.

[0020] In some embodiments of the present invention, in step S4, the multi-wavelength environment is generated using a filter array; the image sensor data is scene data recorded by the imaging device.

[0021] In some embodiments of the present invention, the expression for the condition that the scene to be imaged must satisfy under all wavelengths included in the environment in step S4 is as follows:

[0022]

[0023] in, This represents the imaging device at wavelength λ after removing the diffraction grating. aThe point spread function (SP) obtained by imaging any point in the scene to be imaged is given below. h (·) represents the range of coordinates where the point spread function intensity is much greater than 0 in the horizontal direction. v (·) represents the range of coordinates where the intensity of the point spread function is much greater than 0 in the vertical direction, max[·] represents taking the maximum value, and x0 and y0 are the distance intervals between adjacent impulse functions in the horizontal direction and the vertical direction, respectively.

[0024] In some embodiments of the present invention, in step S4, the expression of the optimization model is as follows:

[0025]

[0026] in, Let I represent all the reconstructed focal plane images, λ represent the image sensor data, λ is an integer index from 1 to T used to refer to different wavelengths in the environment, and O(λ) is the focal plane image corresponding to the wavelength indicated by λ. It is the variable to be optimized in the optimization model. G (x,y;λ) is the optically encoded response of the image on the focal plane at the wavelength indicated by λ. Ψ represents the convolution operation, Ψ represents the first-order difference operation in the horizontal and vertical directions, and τ represents the coefficient used to control the weight of the regularization term.

[0027] In some embodiments of the present invention, the optimization model is solved using the parallel near-end FISTA algorithm.

[0028] The present invention also provides a diffraction-based light field imaging system, including a processor and a memory, wherein the memory stores a computer program that can be executed by the processor to implement the method described above.

[0029] The present invention also provides a computer-readable medium storing a computer program that can be executed to implement the method described above.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] This invention utilizes lenses with axial chromatic aberration to focus each wavelength in a multi-wavelength imaging scene onto planes at different depths. Simultaneously, a diffraction grating is used to give each wavelength's corresponding focused plane image a unique optical code, enabling computational acquisition of multi-focus plane light fields. Furthermore, this invention utilizes the acquired data, the optical code response of each focused plane image, and an optimized model based on the imaging characteristics of the acquisition device to achieve computational reconstruction of the multi-focus plane light field. Compared to existing multi-focus plane light field imaging systems that require sequential scanning of each focused plane using mechanical equipment or electrically adjustable optical elements, the method of this invention can achieve single-exposure acquisition of multi-focus plane light fields, completing light field acquisition for dynamic scenes. This has significant implications for the promotion and application of light field imaging technology. Attached Figure Description

[0032] Figure 1 is a flowchart of the diffraction-based light field imaging method in an embodiment of the present invention;

[0033] Figure 2A shows a scene image captured by the imaging device in Example 1 in an environment containing light with wavelengths of 632.8 nm, 532 nm and 441.6 nm.

[0034] Figure 2B is a focusing plane image corresponding to the 632.8 nm wavelength light in Example 1;

[0035] Figure 2C is a focusing plane image corresponding to the 532 nm wavelength light in Example 1;

[0036] Figure 2D is a focusing plane image corresponding to the 441.6 nm wavelength light in Example 1. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the drawings, not all structures. The diffraction-based light field imaging method utilizes optical elements to diffract and modulate the amplitude and / or phase of the light field to complete the computational acquisition of light field data. Subsequently, an imaging model and reconstruction algorithm are constructed based on the imaging characteristics of the acquisition device to achieve computational reconstruction of the light field data. This method can acquire high-dimensional light field data using a two-dimensional sensor in a single exposure, solving the problem that existing multi-focusing-plane light field acquisition methods are not suitable for dynamic scenes. The axial chromatic aberration of a lens allows each wavelength in the imaging scene to be focused at different depths, while a diffraction grating can periodically modulate the amplitude and / or phase of the incident light. It possesses spectral and dispersive characteristics, providing unique optical encoding for the focused-plane images formed by different wavelengths of light. Therefore, combining the axial chromatic aberration of the lens and the optical encoding of the grating to achieve computational acquisition and reconstruction of the light field has significant implications and promotional value.

[0038] To address the problem that existing multi-focus plane light field acquisition methods cannot simultaneously capture multiple focus plane images in a single exposure and are not suitable for acquiring light fields in dynamic scenes, this invention proposes a diffraction-based light field imaging method and system.

[0039] This invention provides a diffraction-based light field imaging method, comprising the following steps: S1: Constructing an imaging device including a lens with axial chromatic aberration, a diffraction grating, and an image sensor; S2: Using the imaging device to image a point light source located on the optical axis, moving the point light source to adjust its distance from the lens with axial chromatic aberration so that the imaging result of the point light source has the smallest circle of confusion on the image sensor plane, capturing the focused imaging image of the point light source, and calibrating the distance from the diffraction grating to the image sensor; S3: Calculating the optical coding response of the focal plane image corresponding to each wavelength based on the calibrated distance from the diffraction grating to the image sensor and the diffraction efficiency of the diffraction grating; S4: Using the imaging device to image a scene that meets the conditions in a multi-wavelength environment, substituting the data from the image sensor and the optical coding response into an optimization model to reconstruct all focal plane images.

[0040] In a preferred embodiment, the imaging device in step S1 comprises an axial chromatic lens, a diffraction grating, and an image sensor arranged in parallel along the optical axis. The axial chromatic lens provides the imaging device with a focal length that varies with wavelength, enabling the imaging device to simultaneously image multiple focal plane positions using light of different wavelengths in a single exposure. The diffraction grating provides the imaging device with an optically encoded response that varies with wavelength, ensuring that each focal plane image acquired by the imaging device receives a unique encoding, thereby allowing multiple aliased focal plane images to be separated by computation. The image sensor can be a CMOS sensor or a CCD sensor, which is used to record the multiple optically encoded focal plane images.

[0041] In a preferred embodiment, step S2, calibrating the distance from the diffraction grating to the image sensor, includes the following steps:

[0042] S2-1. Binarize the focused imaging image;

[0043] S2-2, Obtain the centroid position of the connected components in the binarized focused imaging image;

[0044] S2-3. Calculate the centroid spacing of the connected regions between adjacent diffraction image points in the horizontal and vertical directions, respectively.

[0045] S2-4. Calculate the distance from the diffraction grating to the image sensor based on the centroid spacing, using the following expression:

[0046]

[0047] Where z represents the distance from the diffraction grating to the image sensor, h represents the horizontal direction, v represents the vertical direction, and λ p The wavelength d represents the point light source. h d represents the period of the diffraction grating along the horizontal direction. v Δ represents the period of the diffraction grating along the vertical direction. i h The centroid spacing in the horizontal direction represents the connected domains between adjacent diffraction image points in the i-th group. denoted by , represents the centroid spacing of the connected domains between adjacent diffraction image points in the j-th group in the vertical direction, K represents the number of centroid spacings in the horizontal direction, and L represents the number of centroid spacings in the vertical direction.

[0048] In a preferred embodiment, in step S3, the expression for the optically encoded response of the focal plane image corresponding to each wavelength is as follows:

[0049]

[0050] Where x represents the horizontal coordinate value, y represents the vertical coordinate value, and λ a Represents wavelength, h G (x,y;λ a ) represents wavelength λ a The corresponding optically encoded response of the focused plane image, where m represents the diffraction order of the diffraction grating in the horizontal direction, n represents the diffraction order of the diffraction grating in the vertical direction, |C m,n (λ a )| 2 The diffraction grating represents the wavelength λ. a The diffraction efficiency of the (m,n)th order diffraction order, where δ(·) represents the unit impulse function, and x0 = λ a z / d h y0 = λ represents the distance interval between adjacent impulse functions in the horizontal direction. a z / d v The z and d represent the distance interval between adjacent impulse functions in the vertical direction. h and d v These are the distance from the diffraction grating to the image sensor, the period of the diffraction grating along the horizontal direction, and the period of the diffraction grating along the vertical direction, respectively.

[0051] In a preferred embodiment, in step S4, the multi-wavelength environment is generated using a filter array; the image sensor data is scene data recorded by the imaging device.

[0052] In a preferred embodiment, the expression for the conditions that the scene to be imaged must satisfy under all wavelengths included in the environment in step S4 is as follows:

[0053]

[0054] Among them, PSF λa This represents the imaging device at wavelength λ after removing the diffraction grating. a The point spread function (SP) obtained by imaging any point in the scene to be imaged is given below. h (·) represents the range of coordinates where the point spread function intensity is much greater than 0 in the horizontal direction. v (·) represents the range of coordinates where the intensity of the point spread function is much greater than 0 in the vertical direction, max[·] represents taking the maximum value, and x0 and y0 are the distance intervals between adjacent impulse functions in the horizontal direction and the vertical direction, respectively.

[0055] In a preferred embodiment, in step S4, the expression of the optimization model is as follows:

[0056]

[0057] in, Let I represent all the reconstructed focal plane images, λ represent the image sensor data, λ is an integer index from 1 to T used to refer to different wavelengths in the environment, and O(λ) is the focal plane image corresponding to the wavelength indicated by λ. It is the variable to be optimized in the optimization model. G (x,y;λ) is the optically encoded response of the image on the focal plane at the wavelength indicated by λ. Ψ represents the convolution operation, Ψ represents the first-order difference operation in the horizontal and vertical directions, and τ represents the coefficient used to control the weight of the regularization term.

[0058] In a preferred embodiment, the optimization model in step S4 is solved using the parallel near-end FISTA algorithm.

[0059] This invention also provides a diffraction-based light field imaging system, including a processor and a memory, wherein the memory stores a computer program that can be executed by the processor to implement the method described above.

[0060] This invention also provides a computer-readable medium storing a computer program that can be executed to implement the method described above.

[0061] This invention proposes a diffraction-based light field imaging method and system. It utilizes the axial chromatic aberration of a lens to focus each wavelength in the imaging scene onto planes at different depths, and employs a diffraction grating to give each wavelength's corresponding focused plane image a unique optical code. Compared to existing methods, this invention's method can simultaneously acquire information from multiple focused planes in a single exposure, completing the light field acquisition of dynamic scenes. This has significant implications for the promotion and application of light field imaging technology.

[0062] In specific implementation schemes, the following methods can be used. It should be noted that the specific methods described in the following implementation process (including methods for calibrating the distance between the grating and the sensor, etc.) are merely illustrative examples, and the scope of the embodiments of the present invention is not limited to these listed methods.

[0063] Example 1

[0064] S1: Construct an imaging device consisting of a lens with axial chromatic aberration, a diffraction grating, and an image sensor.

[0065] Specifically, the lens with axial chromatic aberration can be a biconvex spherical single lens of model GCL-010221 from Daheng Optoelectronics. Its aperture diameter can be further set to 6 mm to reduce other aberrations such as spherical aberration while ensuring axial chromatic aberration. This lens enables the imaging device to simultaneously image multiple focal plane positions using light of different wavelengths in a single exposure. The diffraction grating can be a one-dimensional rectangular wave amplitude grating with a period of 40 micrometers and a duty cycle of 0.5. This diffraction grating provides the imaging device with an optical encoding response that varies with wavelength, so that each focal plane image acquired by the imaging device can be uniquely encoded. The image sensor can be a CMOS sensor, which can record multiple optically encoded focal plane images.

[0066] S2: Using the imaging device of S1, an image is formed on a point light source located on the optical axis. The point light source is moved to adjust its distance from the axial chromatic aberration lens so that the imaging result of the point light source has the smallest circle of confusion on the image sensor plane. The focused imaging image of the point light source is captured and the distance from the grating to the sensor is calibrated.

[0067] Specifically, the point light source can be generated by focusing a 532 nm laser using an objective lens; the distance from the point light source to the axial chromatic aberration lens can be adjusted using a three-dimensional translation stage; the method for calibrating the distance from the grating to the sensor includes the following steps:

[0068] (1) Binarized focused imaging image;

[0069] (2) Obtain the centroid positions of connected components in the binarized image;

[0070] (3) Calculate the centroid spacing of the connected domains between adjacent diffraction image points in the horizontal and vertical directions respectively;

[0071] (4) The distance from the grating to the sensor is calculated from the centroid spacing using the following formula:

[0072]

[0073] Where z represents the distance from the grating to the sensor, h represents the horizontal direction, v represents the vertical direction, and λ p The wavelength d represents the point light source. h d represents the period of the grating along the horizontal direction. v Δ represents the period of the grating along the vertical direction. i h Δ represents the centroid spacing of the connected regions between adjacent diffraction image points of the i-th group in the horizontal direction. v j The centroid spacing represents the centroid interval of the connected domain between adjacent diffraction image points of the j-th group in the vertical direction, K represents the number of centroid intervals in the horizontal direction, and L represents the number of centroid intervals in the vertical direction.

[0074] S3: Calculate the optical coding response of the focal plane image corresponding to each wavelength based on the distance from the grating to the sensor and the diffraction efficiency of the grating obtained from calibration.

[0075] Specifically, the distance from the grating to the sensor is obtained in step S2; the diffraction efficiency of the grating can be obtained through actual measurement, simulation, literature review, etc.; the optical coding response of the focal plane image corresponding to each wavelength is given by the following formula:

[0076]

[0077] Where x represents the horizontal coordinate value, y represents the vertical coordinate value, and λ a Represents wavelength, h G (x,y;λ a ) represents wavelength λ a The corresponding optically encoded response of the focused plane image, where m represents the diffraction order of the grating in the horizontal direction, n represents the diffraction order of the grating in the vertical direction, and |C m,n (λ a )| 2 The diffraction grating represents the wavelength λ. a The diffraction efficiency of the (m,n)th order diffraction order, where δ(·) represents the unit impulse function, and x0 = λ a z / d h y0 = λ represents the distance interval between adjacent impulse functions in the horizontal direction. a z / d v The z and d represent the distance interval between adjacent impulse functions in the vertical direction. h and d v These are the distance from the diffraction grating to the image sensor, the period of the diffraction grating along the horizontal direction, and the period of the diffraction grating along the vertical direction, respectively.

[0078] S4: Using the imaging device of S1, imaging a scene that meets certain conditions in an environment containing multi-wavelength light, and inputting image sensor data and optical coding response into the optimization model to separate the aliased multiple focal plane images.

[0079] Specifically, a multi-wavelength environment can be generated using a filter array; the image sensor data is the scene data recorded by the imaging device in S1; the optical coding response is calculated by S3 based on the wavelengths in the scene; the scene to be imaged must satisfy the condition that the following formula holds true for all wavelengths contained in the environment:

[0080]

[0081] Among them, PSFλa After the light field imaging device in step S1 removes the grating, it operates at wavelength λ. a The point spread function (SP) obtained by imaging any point in the scene to be imaged is given below. h (·) represents the range of coordinates where the point spread function intensity is much greater than 0 in the horizontal direction. v (·) represents the range of coordinates where the intensity of the point spread function is much greater than 0 in the vertical direction, max[·] represents taking the maximum value, and x0 and y0 are the distance intervals between adjacent impulse functions in the horizontal direction and the vertical direction, respectively.

[0082] The optimization model is given by the following formula:

[0083]

[0084] in, Let I represent all the reconstructed focal plane images, λ represent the image sensor data, λ is an integer index from 1 to T used to refer to different wavelengths in the environment, and O(λ) is the focal plane image corresponding to the wavelength indicated by λ. It is the variable to be optimized in the optimization model. G (x,y;λ) is the optically encoded response of the image on the focal plane at the wavelength indicated by λ. Ψ represents the convolution operation, Ψ represents the first-order difference operation in the horizontal and vertical directions, and τ represents the coefficient used to control the weight of the regularization term. This optimization model can be solved using the parallel near-end FISTA algorithm (an iterative convex optimization model solver).

[0085] Figure 2A shows the scene image acquired by the imaging device in S1 of this embodiment in an environment containing light with wavelengths of 632.8 nm, 532 nm, and 441.6 nm simultaneously. Calibration in S2 determined that the distance from the grating to the sensor in the imaging device of S1 is 38.4 mm, and the scene to be imaged meets the conditions in S4. Figures 2B, 2C, and 2D respectively show the focused plane images corresponding to the 632.8 nm wavelength light, the 532 nm wavelength light, and the 441.6 nm wavelength light, calculated and reconstructed using the optimization model in S4. From the results of this embodiment, it can be seen that the diffraction-based light field imaging method and system proposed in this embodiment utilizes the axial chromatic aberration of the lens to focus each wavelength in the imaging scene onto planes at different depths. The diffraction grating gives each wavelength's corresponding focused plane image a unique optical code, achieving single-exposure acquisition of multiple focused plane information and completing the light field acquisition of a dynamic scene.

[0086] The above description provides a further detailed explanation of the present invention in conjunction with specific / preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the scope of protection of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. A diffraction-based optical field imaging method, characterized in that, The process includes the following steps: S1: Constructing an imaging device including a lens with axial chromatic aberration, a diffraction grating, and an image sensor; S2: Using the imaging device to image a point light source located on the optical axis, moving the point light source to adjust its distance from the lens with axial chromatic aberration so that the imaging result of the point light source has the smallest circle of confusion on the plane of the image sensor, capturing the focused imaging image of the point light source, and calibrating the distance from the diffraction grating to the image sensor. The calibration of the distance from the diffraction grating to the image sensor includes the following steps: S2-1: Binarizing the focused imaging image; S2-2: Obtaining the centroid positions of connected components in the binarized focused imaging image; S2-3: Calculating the centroid spacing of connected components between adjacent diffraction image points in the horizontal and vertical directions; S2-4: Calculating the distance from the diffraction grating to the image sensor from the centroid spacing, using the following expression: ;in, This represents the distance from the diffraction grating to the image sensor. Represents the horizontal direction. Represents the vertical direction. The wavelength representing a point light source, This represents the period of the diffraction grating along the horizontal direction. This represents the period of the diffraction grating along the vertical direction. Representing the The centroid spacing of the connected regions between adjacent diffraction image points in the horizontal direction. Representing the The centroid spacing in the vertical direction of the connected regions between adjacent diffraction image points of a group. This represents the number of centroid intervals in the horizontal direction. S3: Based on the distance from the diffraction grating to the image sensor obtained from the calibration and the diffraction efficiency of the diffraction grating, the optical coding response of the focal plane image corresponding to each wavelength is calculated. The expression for calculating the optical coding response of the focal plane image corresponding to each wavelength is as follows: ;in, Represents the coordinate value in the horizontal direction. Represents the coordinate values ​​in the vertical direction. Represents wavelength, Representative wavelength The optically encoded response of the corresponding focal plane image, This represents the diffraction order of the diffraction grating in the horizontal direction. This represents the diffraction order of the diffraction grating in the vertical direction. Represents the diffraction grating at wavelength Next The diffraction efficiency of the first diffraction order. Represents the unit impulse function. This represents the distance interval between adjacent impulse functions in the horizontal direction. This represents the distance interval between adjacent impulse functions in the vertical direction. 、 and These are the distance from the diffraction grating to the image sensor, the period of the diffraction grating along the horizontal direction, and the period of the diffraction grating along the vertical direction, respectively; S4: Using the imaging device, image the scene that meets the conditions in a multi-wavelength environment, and substitute the data from the image sensor and the optical coding response into the optimization model to calculate and reconstruct all focal plane images. The expression of the optimization model is as follows: ;in, Represents all focal plane images obtained from computational reconstruction. Represents image sensor data, The value ranges from 1 to Integer indices are used to refer to different wavelengths in the environment. yes The focal plane image corresponding to the wavelength referred to is the variable to be optimized in the optimization model. yes The optical encoded response of the image on the focal plane at the wavelength indicated. Represents the convolution operation. This represents the first-order difference operation in the horizontal and vertical directions. This represents the coefficient used to control the weight of the regularization term.

2. The diffraction-based light field imaging method as described in claim 1, characterized in that, In step S1, the lens with axial chromatic aberration is used to provide the imaging device with a focal length that varies with wavelength; the diffraction grating is used to provide the imaging device with an optically encoded response that varies with wavelength; the image sensor is used to record multiple optically encoded images of the focal plane; the image sensor is selected from a CMOS sensor or a CCD sensor; the lens with axial chromatic aberration, the diffraction grating, and the image sensor are placed parallel to each other along the optical axis.

3. The diffraction-based light field imaging method as described in claim 1, characterized in that, In step S4, the multi-wavelength environment is generated using a filter array; the image sensor data is scene data recorded by the imaging device.

4. The diffraction-based light field imaging method as described in claim 1 or 3, characterized in that, In step S4, the expression for the conditions that the scene to be imaged must satisfy under all wavelengths included in the environment is as follows: ;in, This represents the imaging device after removing the diffraction grating at a wavelength. The point spread function obtained by imaging any point in the scene to be imaged is given below. This represents the size of the coordinate range where the point spread function intensity is much greater than 0 in the horizontal direction. This represents the size of the coordinate range where the point spread function intensity is much greater than 0 in the vertical direction. This represents taking the maximum value. and These are the distance intervals between adjacent impulse functions in the horizontal direction and the distance intervals between adjacent impulse functions in the vertical direction, respectively.

5. The diffraction-based light field imaging method as described in claim 1, characterized in that, The optimization model is solved using the parallel near-end FISTA algorithm.

6. A diffraction-based optical field imaging system, characterized in that, It includes a processor and a memory, wherein the memory stores a computer program that can be executed by the processor to implement the method as described in any one of claims 1 to 5.

7. A computer-readable medium, characterized in that, The device contains a computer program that can be executed to implement the method as described in any one of claims 1 to 5.

Images