Snapshot infrared light field spectrometer

Abstract

The present application relates to the field of optical technology, provide a kind of snapshot infrared light field spectrum imager, including light field imaging system, collimating system, fold mirror, multiple interference imaging system, relay imaging system and infrared detector;Light field imaging system includes front objective and microlens array, multiple interference imaging system includes diaphragm array, lens array, beam splitter, compensation plate, low-order ladder micro-mirror and high-order ladder micro-mirror;Snapshot infrared light field spectrum imager provided by the present application, working wave band can cover full infrared wave band, reaction target thermal radiation characteristic, little by environment, easy to detect and identify hidden target, and the characteristic peak distribution of infrared wave band is dense, and application space is wide.

Description

Technical Field

[0001] This invention relates to the field of optical technology, specifically providing a snapshot-type infrared light field spectral imager. Background Technology

[0002] Light field spectral imaging technology organically integrates light field imaging technology and spectral imaging technology to realize the detection and reconstruction of the target's full-light information (seven-dimensional light field data (x,y,z,θ,φ,λ,t)). It has broad application prospects in fields such as biomedicine, target recognition, particle image velocimetry, and environmental monitoring.

[0003] Currently, most light field spectral imaging technologies achieve the detection of all-optical information by scanning the target scene from multiple angles or using multiple detectors (including detector arrays). For example, Ben-Gurion University in Israel proposed a compressed four-dimensional spectral stereo imaging technology, which scans a liquid crystal compressed hyperspectral imaging system in a horizontal plane along a direction perpendicular to the system's optical axis, acquiring hyperspectral images at equidistant locations, and reconstructing depth information through a panoramic imaging algorithm. Nanjing University proposed a multispectral light field imaging technology based on a multi-camera array, which uses multiple cameras with different bandwidth filters to capture multispectral light field information and reconstructs the depth of the target scene through a stereo matching algorithm based on a convolutional neural network. While these technologies can detect all-optical information, their reliance on multi-angle scanning or multiple detectors generally leads to problems such as long scanning time, complex structure, difficulty in lightweighting, and high cost. The snapshot infrared light field spectral imager proposed in this invention organically integrates static multiple interferometry imaging spectroscopy technology with light field imaging technology, enabling single-detector snapshot all-optical detection, and acquiring all-optical information of the target's infrared band in a single measurement.

[0004] The existing technology, Complete plenoptic imaging using a single detector.[J]. Optics express, 2018, 26(20):26495-26510.DOI:10.1364 / OE.26.026495., discloses a snapshot light field spectral imaging system that incorporates a focused light field imaging structure into a snapshot hyperspectral imaging Fourier transform spectrometer. The system uses a single detector to acquire the full optical information of the target and proposes an information decoupling algorithm based on a convolutional neural network to decouple the interference spectral information and the light field information, and reconstructs the spectral information and the light incident angle information respectively to obtain the five-dimensional light field information of the target. Although the system can achieve snapshot detection of light field spectral imaging information, it cannot achieve multi-dimensional light field information detection in the infrared band due to the use of a birefringent prism.

[0005] Currently, the main methods for achieving three-dimensional stereoscopic spectral imaging (light field spectral imaging) detection include: light field spectral imaging technology combining spectral imaging systems with multi-angle scanning detection methods, and snapshot light field spectral imaging technology based on multi-detector arrays. The former requires a scanning process, has a long information acquisition time, cannot perform real-time detection, and its stability cannot be guaranteed, making it unsuitable for acquiring light information from rapidly changing targets. The latter eliminates the need for a scanning process and can achieve snapshot imaging, but its design based on multiple detectors or detector arrays leads to high costs, complex structures, difficulty in lightweighting, high sensitivity to environmental changes, and a huge computational burden in post-processing, making lightweight design difficult to achieve. Other existing light field spectral imagers, such as the Harbin Institute of Technology's technology of incorporating a focused light field imaging structure into a snapshot hyperspectral imaging Fourier transform spectrometer, are limited by their underlying principles and can only be applied to the visible light band, failing to take advantage of the unique advantages of infrared imaging. Summary of the Invention

[0006] This invention addresses the technical problems existing in the prior art by providing a snapshot-type infrared light field spectral imager. Specifically, it organically integrates a non-focusing microlens array light field imaging system with a miniature snapshot-type infrared interferometric imaging spectrometer. The non-focusing microlens array light field imaging system images the target in a single light field onto a relay image plane, while the miniature snapshot-type infrared interferometric imaging spectrometer performs snapshot-type spectral imaging detection on the single light field image. The infrared multidimensional data cube of the target can be obtained on the infrared detector. The snapshot-type infrared light field spectral imager has a compact overall structure, small size, light weight, operates in the infrared band, has high stability, strong environmental adaptability, and can achieve real-time detection of the target's full optical information with a single snapshot, thus solving the bottleneck problem of existing light field spectral imaging technology.

[0007] This invention provides a snapshot infrared light field spectral imager, which includes a light field imaging system, a collimation system, a folding mirror, a multiple interferometric imaging system, a relay imaging system, and an infrared detector. The light field imaging system includes a front objective lens and a microlens array. The target under test is imaged and focused onto the lens surface of the microlens array through the front objective lens, and the light field information is imaged onto a primary relay image plane. The primary relay image plane is located on the image-side focal plane of the microlens array. The multiple interferometric imaging system includes an aperture array, a lens array, a beam splitter, a compensating plate, a low-order step micromirror, and a high-order step micromirror. The primary relay image plane is collimated by the collimation system, reflected by the folding mirror, and then incident on the multiple interferometric imaging system. Aperture-splitting multi-channel imaging is achieved through the aperture array and the lens array. The light is then split by the beam splitter and the compensation plate, and imaged a second time onto the reflecting surfaces of the high-order step-micromirror and the low-order step-micromirror in the form of an optical field image array. Aperture-splitting multi-channel phase modulation is performed, and the modulated optical fields from both paths are reflected a second time back to the beam splitter and the compensation plate, coupling to form an infrared optical field interferometric image array. This image is then imaged onto the back focal plane of the infrared detector through the relay imaging system.

[0008] Preferably, the front objective lens adopts a dual telecentric design, the microlens array is positioned at the focal plane of the front objective lens, and the microlens array includes microlenses. The detection depth range of the light field imaging system... for: ; In the formula, For depth range, The diameter of the microlens. The focal length of the microlens. It is the minimum resolvable size of a relay image plane.

[0009] Preferably, the spatial resolution of the primary light field imaging is the same as the number of microlens arrays.

[0010] Preferably, the number of microlens arrays is Ne × Ne The spatial resolution of the first-order light field imaging is Ne × Ne The infrared detector has P×P pixels, and the angular resolution of the light field imaging system is P / Ne ×P / Ne .

[0011] Preferably, the lens array comprises two-dimensional square lens units, each lens unit being square, having a duty cycle of 100%, and the size of the lens array unit being [missing information]. d l × d l , d l This refers to the side length of the square lens unit. d m Where is the diameter of the microlens, when d l = k × d m The resolution of the light field imaging system is k ×k , k This represents the number of microlens units on one side of the lens unit, i.e., the number of pixels in a single-channel light field imaging.

[0012] Preferably, the multidimensional data cube of the snapshot infrared light field spectral imager is k × k ×P / Ne ×P / Ne × N 2 .

[0013] Preferably, the collimation system is an object-side telecentric system; the aperture array is placed at the front focal plane of the lens array; the lens array is an image-side telecentric system, which images the primary relay image plane through multiple aperture channels onto the multiple interferometric imaging system.

[0014] Preferably, the number of aperture arrays is the same as the number of lens arrays.

[0015] Preferably, the number of aperture arrays is N × N The number of the lens arrays is N × N The low-order micromirror and the high-order micromirror are symmetrically arranged about the beam splitter, and the total number of steps of the high-order micromirror is [number missing]. The step order of the low-step micromirror is: The single-step height of the low-step micromirror is... The single-step height of the high-step micromirror is The low-order micromirror and the high-order micromirror form Phase modulation unit.

[0016] Preferably, when the first The higher-order stepped micromirrors and the first The low-step micromirror forms a phase modulation unit. The modulation optical path difference generated by the phase modulation unit is .

[0017] Compared with the prior art, the present invention can achieve the following beneficial effects: The snapshot infrared light field spectral imager provided by this invention organically integrates light field imaging technology with infrared multiple interferometric spectral imaging technology. It overcomes the problems of existing light field spectral imaging technologies, which are based on multi-angle scanning or multiple detectors and detector arrays, resulting in long scanning times, complex structures, difficult assembly and adjustment, difficulty in weight reduction, and high costs. The snapshot infrared light field spectral imager realizes snapshot detection and information reconstruction of infrared multidimensional light information. At the same time, it adopts a static interferometric system to improve the stability of interferometric spectral information sampling and reduce the size and weight of the system.

[0018] The snapshot-type infrared light field spectral imager provided by this invention can cover the entire infrared band, reflect the thermal radiation characteristics of the target, is less affected by the environment, is easy to detect and identify hidden targets, and has a dense distribution of characteristic peaks in the infrared band, making it widely applicable. Moreover, it can obtain light field interferometric image arrays, and through the decoupling of all-optical information combined with depth reconstruction and spectral data processing, it can obtain three-dimensional stereoscopic spectral data information of the target, specifically obtaining three-dimensional spatial distribution information and infrared spectral information of any voxel. Attached Figure Description

[0019] Figure 1 This is a schematic diagram illustrating the principle of a snapshot infrared light field spectral imager according to a specific embodiment of the present invention; Figure 2 This is a schematic diagram of an interference modulation system based on orthogonal stepped micromirrors according to a specific embodiment of the present invention; Figure 3 This is a schematic diagram of a non-focused light field imaging system according to a specific embodiment of the present invention; Figure 4 This is a schematic diagram illustrating the principle of light field information representation according to a specific embodiment of the present invention; Figure 5 This is a schematic diagram of the front optical path in a multiple interferometric imaging system according to a specific embodiment of the present invention; Figure 6 This is a schematic diagram of the multidimensional optical information decoupling and reconstruction process according to a specific embodiment of the present invention; Figure 7 This is a schematic diagram of the optical field-interference information decoupling process according to a specific embodiment of the present invention; Figure 8 This is a schematic diagram of a ray-Gaussian convolution kernel according to a specific embodiment of the present invention; Figure 9 This is a flowchart of a depth reconstruction algorithm based on scale-depth space according to a specific embodiment of the present invention; Figure 10 This is a schematic diagram of a stepped micromirror substrate stacking device according to a specific embodiment of the present invention.

[0020] Figure label: 1-Object plane; 2-Front objective lens; 3-Microlens array; 31-Primary relay image plane; 4-Collimating lens; 5-Folding mirror; 6-Aperture array; 7-Lens array; 8-Beam splitter and compensator; 9-High-order tiered micromirrors; 10-Low-order tiered micromirrors; 11-Relay imaging system; 12-Infrared detector. Detailed Implementation

[0021] In the following description, embodiments of the invention will be described with reference to the accompanying drawings. In the description below, the same modules are denoted by the same reference numerals. Where the same reference numerals are used, their names and functions are also the same. Therefore, their detailed description will not be repeated.

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0023] In a specific embodiment of the present invention, a snapshot infrared light field spectral imager is provided, which includes a light field imaging system, a collimation system, a folding mirror, a multiple interferometric imaging system, a relay imaging system, and an infrared detector. The light field imaging system includes a front objective lens and a microlens array. The target under test is imaged and focused onto the lens surface of the microlens array through the front objective lens, and the light field information is imaged onto a primary relay image plane, which is located on the image-side focal plane of the microlens array. The multiple interferometric imaging system includes an aperture array, a lens array, a beam splitter, a compensating plate, a low-order step micromirror, and a high-order step micromirror. The primary relay image plane is collimated by the collimation system, reflected by the folding mirror, and then incident on the multiple interferometric imaging system. Aperture-splitting multi-channel imaging is achieved through the aperture array and the lens array. The beam is split by the beam splitter and the compensation plate, and then projected a secondary image onto the reflecting surfaces of the high-order step-micromirror and the low-order step-micromirror in the form of an optical field image array. Aperture-splitting multi-channel phase modulation is performed, and the modulated optical fields from both paths are reflected a second time to the beam splitter and the compensation plate, coupling to form an infrared optical field interferometric image array. This image is then projected onto the back focal plane of the infrared detector through the relay imaging system. Specifically, the infrared detector can be an infrared external array detector.

[0024] In a specific implementation, the front objective lens adopts a double telecentric design, the microlens array is positioned at the focal plane of the front objective lens, and the microlens array includes microlenses. The detection depth range of the light field imaging system is... for: ; In the formula, For depth range, The diameter of the microlens. The focal length of the microlens. It is the minimum resolvable size of a relay image plane.

[0025] In a specific implementation, the spatial resolution of the single-stage light field imaging is the same as the number of microlens arrays; the number of microlens arrays is... Ne × Ne The spatial resolution of the first-order light field imaging is Ne × Ne The infrared detector has P×P pixels, and the angular resolution of the light field imaging system is P / Ne ×P / Ne .

[0026] In a specific embodiment, the lens array includes two-dimensional square lens units, each lens unit being square with a 100% duty cycle, and the size of the lens array unit being... d l × d l ,like d l = k × d m The resolution of the light field imaging system is then... k × k The multidimensional data cube of the snapshot infrared light field spectral imager is... k × k ×P / Ne ×P / Ne × N 2 .

[0027] In a specific implementation, the collimation system is an object-side telecentric system; the aperture array is placed at the front focal plane of the lens array; the lens array is an image-side telecentric system, which images the primary relay image plane through multiple aperture channels onto the multiple interferometric imaging system.

[0028] In a specific implementation, the number of aperture array units is the same as the number of lens array units; the number of aperture array units is... N × N The number of lens units in the lens array is N × NThe low-echelon micromirror and the high-echelon micromirror are symmetrically arranged about the beam splitter, and the low-echelon micromirror and the high-echelon micromirror form a Phase modulation unit.

[0029] In a specific implementation, the total number of steps in the high-step micromirror is: The step order of the low-step micromirror is: The single-step height of the low-step micromirror is To satisfy the principle of optical path difference complementarity, the single step height of the high-echelon micromirror is... Two stepped micromirrors are placed symmetrically about the beam splitter, forming a beam splitter. The phase modulation unit, and the optical field interferometric image array after each optical field imaging unit is phase modulated accordingly, contain complete three-dimensional spatial distribution information and spectral information of the target, wherein the spectral sampling points are... When the first Advanced tiered micromirrors and the first Low-level step-down micromirrors form phase modulation units The modulation optical path difference generated by the phase modulation unit is .

[0030] The snapshot infrared light field spectral imager provided by this invention organically integrates light field imaging technology with infrared multiple interferometric spectral imaging technology. It overcomes the problems of existing light field spectral imaging technologies, which are based on multi-angle scanning or multiple detectors and detector arrays, resulting in long scanning times, complex structures, difficult assembly and adjustment, difficulty in weight reduction, and high costs. The snapshot infrared light field spectral imager realizes snapshot detection and information reconstruction of infrared multidimensional light information. At the same time, it adopts a static interferometric system to improve the stability of interferometric spectral information sampling and reduce the size and weight of the system.

[0031] The snapshot-type infrared light field spectral imager provided by this invention can cover the entire infrared band, reflect the thermal radiation characteristics of the target, is less affected by the environment, is easy to detect and identify hidden targets, and has a dense distribution of characteristic peaks in the infrared band, making it widely applicable. Moreover, it can obtain light field interferometric image arrays, and through the decoupling of all-optical information combined with depth reconstruction and spectral data processing, it can obtain three-dimensional stereoscopic spectral data information of the target, specifically obtaining three-dimensional spatial distribution information and infrared spectral information of any voxel.

[0032] The following detailed description, in conjunction with specific embodiments, provides further details.

[0033] Example like Figure 1The diagram shows the structure of a snapshot infrared light field spectral imager provided in this specific embodiment of the present invention. As can be seen from the diagram, the main structure includes an object plane 1, a front objective lens 2, a microlens array 3, a collimating lens 4, a folding mirror 5, an aperture array 6, a lens array 7, a lightweight beam splitter and compensation plate 8, a high-order multi-stage micromirror 9, a low-order multi-stage micromirror 10, a relay imaging system 11, and an infrared detector 12. The front objective lens 2 and the microlens array 3 constitute a non-focusing light field imaging system, which performs light field imaging on the target object. A single light field image is formed on a single relay image plane 31. The collimating lens... 4. The primary light field imaging is collimated and modulated. To reduce the size of the instrument, the optical path is folded and compressed by the folding mirror 5. The aperture array 6 and lens array 7 converge the imaging channels of the primary light field imaging. The imaging is then projected onto the reflecting surfaces of the high-step multi-stage micro-mirrors 9 and the low-step multi-stage micro-mirrors 10 through a lightweight beam splitter and compensation plate 8. The primary light field imaging is phase-modulated to obtain an optical field interferometric image array carrying spectral and spatial light field information. This array is coupled to the back focal plane of the infrared detector 12 by the relay imaging system 11. The target's all-optical information is then decoupled and reconstructed through the infrared optical field interferometric image array.

[0034] In this specific embodiment, the front objective lens 2 adopts a dual telecentric design, and the microlens array 3 is placed at the focal plane of the front objective lens 2. The microlens array 3 includes microlenses, and the detection depth range of the light field imaging part is... As shown in equation (1): (1) In the formula, For depth range, The diameter of the microlens. This is the focal length of the microlens, which is the distance from the microlens to the primary relay image plane 31. It is the minimum resolvable size of the relay image plane 31.

[0035] In this specific embodiment, the number of microlens arrays 3 is Ne × Ne The spatial resolution of a single light field imaging is... Ne × Ne The collimation system, i.e., collimating lens 4, is an object-side telecentric system. The aperture array 6 is positioned at the front focal plane of the lens array 7. The number of aperture arrays 6 is... N × N Lens array 7 is an image-side telecentric system, and the number of lenses in lens array 7 is [number missing]. N × N A 31-min aperture multi-channel image is formed on a static interferometer system using a single relay image plane; a lightweight beam splitter and compensating plate 8 perform phase modulation on the incident light field splitting path; the lens array 7 is arranged in a two-dimensional square configuration, with each lens unit being square, having a duty cycle of 100%, and dimensions of [missing information]. dl × d l ,like d l = k × d m Then the resolution of the light field imaging is k × k If the number of pixels of infrared detector 12 is P×P, then the angular resolution of the light field imaging system is P / Ne ×P / Ne .

[0036] In this specific embodiment, Figure 2 This is a schematic diagram of an interferometric modulation system based on orthogonal stepped micromirrors. As can be seen from the diagram, the height of the low-step multi-stage micromirror 10 is... To satisfy the principle of optical path difference complementarity, the height of the high-step multi-stage micromirror 9 is... The low-level echelle micromirror 10 and the high-level echelle micromirror 9 are placed symmetrically about the beam splitter 8, forming a beam splitter. The phase modulation unit, and the light field interferometric image array after each light field imaging unit is phase modulated according to the corresponding phase, contains complete three-dimensional spatial distribution information and spectral information of the target, where the spectral sampling points are... N 2 The multidimensional data cube of the snapshot infrared light field spectral imager is k × k ×P / Ne ×P / Ne × N 2 .

[0037] In this specific embodiment, the total number of steps in the high-step micromirror is: The step order of the low-step micromirror is: The single-step height of the low-step micromirror is To satisfy the principle of optical path difference complementarity, the single step height of the high-echelon micromirror is... Two stepped micromirrors are placed symmetrically about the beam splitter, forming a beam splitter. The phase modulation unit, and the optical field interferometric image array after each optical field imaging unit is phase modulated accordingly, contain complete three-dimensional spatial distribution information and spectral information of the target, wherein the spectral sampling points are... When the first Advanced tiered micromirrors and the first Low-level step-down micromirrors form phase modulation units The modulation optical path difference generated by the phase modulation unit is .

[0038] In this specific embodiment, the relay imaging system 11 couples the optical field interferometric image array to the back focal plane of the infrared detector 12. The relay imaging system 11 adopts an object-side telecentric optical path design and an achromatic and thermal design.

[0039] In this specific embodiment, all-optical information To conduct detection, depth information z It can be determined by the angle of light incidence. Reconstruction.

[0040] In this specific embodiment, Figure 3 and Figure 4 These are schematic diagrams of a non-focused light field imaging system and a schematic diagram illustrating the principle of representing light field information. Figure 3 S1, S2, and S3 represent object points at different depths, and S1ˊ, S2ˊ, and S3ˊ are primary imaging points of the object points. As can be seen from the figure, in order to achieve accurate positioning of each pixel and detection of light field intensity, a four-dimensional light field is established between the microlens array 3 and the primary relay image plane 31. The mathematical matrix transfer model, in which, These are the focal plane coordinates of the detector. Let the coordinates be those of the target principal plane. Let represent the coordinates of the sub-microlenses on the microlens array. The coaxial spatial translation, rotation, and off-axis spatial translation transformation matrices are derived, a microlens light field sampling model is established, and the microlens mapping detection area is divided. This allows us to determine the geometric correspondence between the target point and the pixel point. Furthermore, by establishing a light field radiation model, we can derive the image point light intensity for each matrix coordinate.

[0041] In this specific embodiment, to reconstruct the depth information of the target point, a scale-depth transformation algorithm is used to cubic the four-dimensional light field data of the interferometric channel image unit. Perform deep reconstruction.

[0042] In this specific embodiment, Figure 5 This is a schematic diagram of the front optical path of a multiple interferometric imaging system. As can be seen from the figure, the crosstalk problem between spectral channels is solved by the aperture stop array 6. After the target object is imaged by the optical field imaging part is collimated by the collimating lens, it passes through the aperture stop array and the lens array in sequence to obtain multiple imaging with different apertures. The image-side telecentric design of each interference channel realizes the equal optical path difference modulation of the principal rays of each field of view.

[0043] In this specific embodiment, Figure 6This diagram illustrates the decoupling and reconstruction process of multidimensional optical information. As shown, the system directly detects the optical field interferometric image array, obtains the optical field interferogram data cube through image processing, and then obtains the interferometric image data cube and the optical field images of each channel through interferometric optical field demixing. The spectral information of the interferometric image data cube can be demodulated through Fourier transform processing. In the scale-depth space, the disparity information of the optical field image is demodulated through a spatial transformation algorithm, and the depth distribution is reconstructed. When all-optical information is ignored... In the case of higher than the detector's temporal resolution variation and neglecting light obstruction and loss, the all-optical function is: The intensity distribution of the light field interference image array is derived as shown in equation (2): (2) In the formula, P It is a phantom optical function. The light intensity distribution of the light field interference image array. For the angle of light propagation, For wavelength, i The imaginary unit, for The sampling optical path difference of the coordinate interference channel. .

[0044] In this specific embodiment, the intensity distribution of the light field interference image can be further expressed as: (3) In the formula, For the target four-dimensional light field data cube, by Calculation derivation, The target image spectral data cube.

[0045] In this specific embodiment, Figure 7 This diagram illustrates the decoupling process of light field and interferometric information. As shown, based on the grayscale differences between image units of different interferometric orders, a feature recognition algorithm is used to extract the edge features of the image units. These edge features are then used to decompose each interferometric image unit. Interferometric path difference matching is performed on the image units of each interferometric order to obtain the interferogram data cube. .

[0046] In this specific embodiment, Figure 8 This is a schematic diagram of a ray-Gaussian convolution kernel. As can be seen from the diagram, depth information is reconstructed based on a scale-depth space transformation algorithm using a four-dimensional light field data cube. Extracting from the middle or The slice is a polar plane image (EPI). The parallax relationship between the tilt angle of the linear structure in the EPI and the sub-image is shown in equation (4): (4) In the formula, D The parallax between the uppermost and lowermost sub-images in the sub-image array containing the polar plane image. Q for y Number of sub-images along the axis, p In pixels β The angle of inclination for a linear structure.

[0047] In this specific embodiment, to reconstruct parallax, a scale-depth space with scale-invariant and rotation-invariant properties is constructed using a ray-Gaussian convolution kernel, and extreme points are found within the space. The ray-Gaussian convolution kernel is shown in equation (5): (5) in, For ray-Gaussian convolution kernel, represents the scale parameter of the convolution kernel. The angle parameter of the convolution kernel.

[0048] In this specific embodiment, to achieve a denser target scene depth map, Figure 9 The flowchart shows the depth reconstruction algorithm based on scale-depth space. As can be seen from the figure, the scale-depth space of the light field (Lisad-2) is constructed by the normalized second derivative of the ray-Gaussian convolution kernel to realize the disparity reconstruction of non-edge feature rays (Lisad-1 realizes the disparity reconstruction of edge feature rays).

[0049] In this specific embodiment, to achieve spectral reconstruction, the interference sequence formed by extracting corresponding image points from each image unit is as follows: (6) In the formula, X For sub-image array along u Number of sub-images along the axial direction, Q For sub-image array along v The number of sub-images along the axial direction. The spectral curve can be reconstructed by performing a Fourier transform on the interference intensity sequence.

[0050] In this specific embodiment, a method can be used to fabricate a microstepped mirror by orderly arranging substrates on a wedge-shaped block, which has high process controllability, high precision in controlling the height of the microstepped mirror, high precision in controlling the surface roughness of the reflecting surface, and good repeatability.

[0051] like Figure 10 The diagram shown is a schematic of the stepped micromirror substrate stacking device in this embodiment. Referring to this diagram, the method for fabricating a stepped micromirror by orderly arranging substrates on a wedge-shaped block in this embodiment is as follows: (i) Select N pieces of machinable solid material as the substrate for the micro-step mirror and clean them; (ii) Grind and polish the left and right sides of each substrate to achieve a surface roughness of 0.1nm~1μm, with the left side parallel to the right side and the thickness of each substrate reaching the set size; then clean each substrate after grinding. (III) Stack the N ground substrates in sequence, so that the right side of each substrate is in contact with the left side of the adjacent substrate. After stacking, the upper surface and lower surface of each substrate are coplanar. Then use curing adhesive to bond and fix the stacked substrates together. (iv) Place the substrates prepared in step (iii) on a grinding table and grind the lower surface of each substrate to achieve a surface roughness of 0.1 nm to 1 μm, with the lower surface of the substrate perpendicular to its left and right sides; then remove the cured adhesive with a remover solution and clean each substrate. (v) Select a machinable solid material, grind and polish it into a wedge-shaped block; the lower surface of the wedge-shaped block is a horizontal plane, the upper surface is an inclined plane, the left and right sides are vertical planes, and the included angle between the upper surface and the right side of the wedge-shaped block is... Less than 90°; the surface roughness of the upper and lower surfaces of the wedge reaches 0.1nm~1μm; clean the wedge; (vi) Grind and polish a rectangular block as a substrate, with a surface roughness of 0.1 nm to 1 μm on the upper surface of the substrate; clean the substrate; (vii) Grind and polish a cuboid as a standard block fixed on the substrate; the right side of the standard block is perpendicular to the lower surface, and the surface roughness of the right side and the lower surface reaches 0.1nm~1μm; clean the standard block; (viii) Place the standard block at one end of the base, with the lower surface of the standard block coplanar with the upper surface of the base; then bond and fix the standard block to the base. (ix) Place the wedge block on the base, so that the left side of the wedge block is coplanar with the right side of the standard block, and the lower surface of the wedge block is coplanar with the upper surface of the base; then bond and fix the wedge block to the base. (x) Place each substrate on the wedge block in sequence, with the left side of the first substrate coplanar with the right side of the standard block, the right side of each substrate coplanar with the left side of the adjacent substrate, and the edges of the lower surface of each substrate in complete contact with the upper surface of the wedge block; then bond and fix each substrate together, forming a stepped structure on the lower surface of the substrate. (xi) Deposit an anti-reflection film and a protective film on the upper surface of the stepped structure obtained in step (x).

[0052] low step height d It can be expressed as shown in equation (7): (7) in This refers to the substrate thickness, also known as the step width. The angle of inclination of the wedge block.

[0053] Similarly, the height of higher steps Nd It can be expressed as shown in equation (8): (8) in The wedge angle corresponding to the fabrication of the high-step micromirror.

[0054] Although embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0055] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A snapshot-type infrared light field spectral imager, characterized in that, The snapshot-type infrared light field spectral imager includes a light field imaging system, a collimation system, a folding mirror, a multiple interferometric imaging system, a relay imaging system, and an infrared detector; The light field imaging system includes a front objective lens and a microlens array. The target under test is imaged and focused onto the lens surface of the microlens array through the front objective lens, and the light field information is imaged onto a primary relay image plane. The primary relay image plane is located on the image-side focal plane of the microlens array. The multiple interferometric imaging system includes an aperture array, a lens array, a beam splitter, a compensating plate, a low-order step micromirror, and a high-order step micromirror. The primary relay image plane is collimated by the collimation system, reflected by the folding mirror, and then incident on the multiple interferometric imaging system. Aperture-splitting multi-channel imaging is achieved through the aperture array and the lens array. The beam is split by the beam splitter and the compensation plate, and then projected a secondary image onto the reflecting surfaces of the high-order step-micromirror and the low-order step-micromirror in the form of an optical field image array. Aperture-splitting multi-channel phase modulation is performed, and the modulated optical fields from both paths are reflected a second time to the beam splitter and the compensation plate, coupling to form an infrared optical field interferometric image array. This image is then projected onto the back focal plane of the infrared detector through the relay imaging system. The front objective lens adopts a dual telecentric design, and the microlens array is positioned at the focal plane of the front objective lens. The microlens array includes microlenses, and the detection depth range of the light field imaging system is [not specified]. for: In the formula, For depth range, The diameter of the microlens. The focal length of the microlens. The minimum resolvable size of a relay image plane; The multidimensional data cube of the snapshot infrared light field spectral imager is k × k ×P / Ne ×P / Ne × N 2 , k Where is the number of pixels in single-channel light field imaging, and P is the number of pixels on one side of the infrared detector. Ne Let P be the number of units on one side of the microlens array, and let P be the angular resolution of the light field imaging system. Ne ×P / Ne , The total step order of a high-step micromirror or the step order of a low-step micromirror. When the The higher-order stepped micromirrors and the first The low-step micromirror forms a phase modulation unit. The modulation optical path difference generated by the phase modulation unit is , The single-step height is for the low-step micromirror.

2. The snapshot-type infrared light field spectral imager according to claim 1, characterized in that, The spatial resolution of the single-field imaging is the same as the number of microlens arrays.

3. The snapshot-type infrared light field spectral imager according to claim 2, characterized in that, The number of microlens arrays is Ne × Ne The spatial resolution of the first-order light field imaging is Ne × Ne ; The infrared detector has P×P pixels, and the angular resolution of the light field imaging system is P / Ne ×P / Ne .

4. The snapshot-type infrared light field spectral imager according to claim 3, characterized in that, The lens array comprises two-dimensional square lens units, each lens unit being square with a 100% duty cycle. The dimensions of each lens array unit are as follows: d l × d l , d l This refers to the side length of the square lens unit. d m Where is the diameter of the microlens, when d l = k × d m The resolution of the light field imaging system is k × k , k This represents the number of microlens units on one side of the lens unit, i.e., the number of pixels in a single-channel light field imaging.

5. The snapshot-type infrared light field spectral imager according to claim 1, characterized in that, The collimation system is an object-side telecentric system; the aperture array is placed at the front focal plane of the lens array; the lens array is an image-side telecentric system, which images the primary relay image plane through multiple aperture channels onto the multiple interferometric imaging system.

6. The snapshot-type infrared light field spectral imager according to claim 1, characterized in that, The number of aperture units in the aperture array is the same as the number of lens units in the lens array.

7. The snapshot-type infrared light field spectral imager according to claim 1, characterized in that, The number of aperture arrays is N × N The number of the lens arrays is N × N The low-order micromirror and the high-order micromirror are symmetrically arranged about the beam splitter, and the total number of steps of the high-order micromirror is [number missing]. The step order of the low-step micromirror is: The single-step height of the low-step micromirror is... The single-step height of the high-step micromirror is The low-order micromirror and the high-order micromirror form Phase modulation unit.

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