High-flux bionic multi-aperture multispectral polarization imaging system

Abstract

The present invention relates to a high-light-flux biomimetic multi-aperture multispectral polarization imaging system, comprising a notch filter array, a lens array, and a polarization camera array; the notch filter array comprises a plurality of notch filters; the lens array comprises N camera lenses, each having parallel optical axes and coplanar focal planes; the polarization camera array comprises N polarization cameras, each polarization camera having four polarization states of 0°, 45°, 90°, and 135°, and the detector image planes of the polarization cameras being coplanar; parallel light emitted at different angles by a target passes through the notch filters and lenses and is imaged in the detector image plane of the polarization camera. The present invention enables simultaneous detection and imaging of a target's multispectral and polarization information, and can output images with a higher signal-to-noise ratio than color polarization cameras.

Description

Technical Field

[0001] The invention relates to a high-light-flux bionic multi-aperture multi-spectral polarization imaging system. Background Art

[0002] The multi-aperture imaging system is a novel optoelectronic imaging system designed based on the structure of a bionic compound eye. Compared to single-aperture imaging systems, it offers advantages such as a larger field of view, more information, and the ability to capture images at different scales. For example, the mantis shrimp's compound eye is capable of detecting polarized light, which is imperceptible to the human eye. It can distinguish four linear polarization directions and two circular polarization states, while also simultaneously sensing spectral information across 16 different wavelengths.

[0003] Polarization imaging offers specific advantages. It can not only detect the geometry and surface of an object, but also measure physical properties that are not detectable with conventional imaging. Polarization imaging is often used to enhance the contrast of difficult-to-distinguish objects for target recognition or classification tasks.

[0004] Hyperspectral imaging technology is based on image data from numerous narrowbands. It combines imaging and spectroscopy techniques to detect the two-dimensional geometric space and one-dimensional spectral information of a target, acquiring continuous, narrowband image data with high spectral resolution. However, the presence of narrowband filters significantly reduces the amount of information captured by the detector.

[0005] Notch filters, also known as band-stop filters, have luminous flux characteristics that are opposite to those of narrowband filters. Using notch filters can significantly increase the system's luminous flux compared to using narrowband filters.

[0006] Polarization spectral imaging is a newly developed photoelectric detection technology that combines polarization imaging and spectral imaging techniques. It can simultaneously acquire high-resolution multispectral information about a target's polarization. Compared to traditional detection technologies, polarization spectral imaging captures more information and has broad application prospects.

[0007] Some scholars have combined polarization with narrowband filters to solve the problem that polarization images do not contain spectral information. However, due to the small light transmission range of narrowband filters, the amount of light flux that can be received by the optical system is severely reduced, and the amount of information captured by the detector is small, making it difficult to achieve computational imaging such as high-resolution and high-quality imaging. Summary of the Invention

[0008] In view of this, an object of the present invention is to provide a high-light-flux bionic multi-aperture multi-spectral polarization imaging system to solve the above-mentioned problems.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] A high-light-flux bionic multi-aperture multi-spectral polarization imaging system comprises a notch filter array, a lens array, and a polarization camera array. The notch filter array comprises a plurality of notch filters. The lens array comprises N camera lenses, each with parallel optical axes and coplanar focal planes. The polarization camera array comprises N polarization cameras, each with four polarization states of 0°, 45°, 90°, and 135°. The detector image planes of the polarization cameras are coplanar. Parallel light from a target at different angles passes through the notch filters and lenses and forms an image in the detector image plane of the polarization camera.

[0011] Furthermore, a single notch filter, a camera lens, and a polarization camera form a single aperture structure, and the central axes of the three coincide and align.

[0012] Furthermore, the notch filter array, lens array, and polarization camera array are distributed in a rectangular array.

[0013] Furthermore, the notch filter adopts the Edmund Notch Filter series, and the central wavelength is 405nm, 488nm, 514.5nm, 532nm or 632.8nm.

[0014] Furthermore, the principle of compressed sensing is combined with the prior information of sparsity and smoothness to perform spectral super-resolution calculation on the collected image. The convex optimization equation is as follows:

[0015]

[0016] where ||·|| F represents the F norm, ||·||1 represents the 1 norm, Y represents the data captured by the detector, H represents the system acquisition matrix, D represents the dictionary, B represents the corresponding sparse matrix, λ represents the wavelength independent variable, μ represents the coefficient of the sparse constraint term, and γ represents the coefficient of the spectral smoothness constraint term.

[0017] Furthermore, the same polarization state of different polarization cameras has different spectral information; different polarization states of the same polarization camera have the same spectral information.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention can achieve synchronous detection and imaging of target multispectral information and polarization information, and can output images with higher signal-to-noise ratio than color polarization cameras;

[0020] 2. The detector of the present invention obtains four-dimensional information, namely spatial, multispectral and polarization, which is more conducive to target recognition and classification;

[0021] 3. The present invention can change the spectral range of the detection target by replacing the notch filter or the camera according to actual requirements, thereby realizing flexible data collection for different scenes. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the system structure of the present invention;

[0023] Figure 2 This is a system simulation assembly diagram in one embodiment of the present invention;

[0024] Figure 3 This is a diagram of a single aperture three-dimensional structure in one embodiment of the present invention;

[0025] Figure 4 is a graph showing the quantum effect of a camera according to an embodiment of the present invention;

[0026] Figure 5 is a transmittance curve diagram of a notch filter in one embodiment of the present invention;

[0027] Figure 6 is a diagram showing the distribution of polarization state pixels on a polarization camera chip according to an embodiment of the present invention;

[0028] In the figure: 1-high-throughput bionic multi-aperture multi-spectral polarization imaging system, 2-notch filter array, 3-lens array, 4-camera array. DETAILED DESCRIPTION

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] Please refer to Figure 1-4 This embodiment provides a high-light-flux bionic multi-aperture multi-spectral polarization imaging system, comprising a notch filter array, a lens array, and a polarization camera array; the notch filter array comprises a plurality of notch filters; the lens array comprises four camera lenses, the optical axes of each camera lens are parallel, and the focal planes are coplanar; the polarization camera array comprises four polarization cameras, and the detector image planes of the polarization cameras are coplanar.

[0031] In this embodiment, reference Figure 3 A single notch filter, camera lens and polarization camera form a single aperture structure. The central axes of the three coincide and align. Parallel light from the target at different angles passes through the notch filter and lens and forms an image in the detector image plane of the polarization camera.

[0032] In this embodiment, the notch filter array, lens array, and polarization camera array are preferably arranged in a rectangular array, with a top-bottom center spacing of 50 mm and a left-right center spacing of 50 mm. The array spacing should be minimized as much as possible without affecting operation, thereby reducing the overall size of the system and increasing the field of view overlap between apertures.

[0033] In this embodiment, preferably, each camera chip has four polarization states, namely 0°, 45°, 90°, and 135°. Figure 4 As shown in the figure, the polarization state pixel distribution pattern on the polarization camera chip of the high-throughput bionic multi-aperture multispectral polarization imaging system. If the polarization camera acquires an image as a matrix A with a pixel size of 2448x2048, then the pixel size of each polarization state image is 1224x1024. According to the MATLAB software syntax, polarization state P0 = A(2:2:end,2:2:end), polarization state P 45 =A(1:2:end,2:2:end), polarization state P 90 =A(1:2:end,1:2:end), polarization state P 135 =A(2:2:end,1:2:end).

[0034] In this embodiment, preferably, the notch filter adopts the Edmund Notch Filter series, and the center wavelength adopts 405nm, 488nm, 514.5nm, 532nm or 632.8nm. Taking the center wavelength of 532nm as an example, the optical density OD ≥ 4.0, the coating is Hard Coated, the half-maximum full width is 26.6nm, and the half-maximum full width tolerance is ±2.7. The transmittance curve of the notch filter is as follows: Figure 5 As shown, the average transmittance is about 90%. The lens is an Edmund fixed-focus series model Edmund 85-869, with a focal length of 35mm, an F number of 1.8 to 16, an entrance pupil of 23.68mm, a maximum distortion of -0.02%, a horizontal field of view of 14.3°, a vertical field of view of 10.7°, and a diagonal field of view of 17.8°. The polarization camera is a FLIR BFS-U3 series, model BFS-U3-51S5P, with a resolution of 2448x2048, a pixel size of 3.45μm, and a chip of Sony IMX250, CMOS, 2 / 3". The quantum effect curves of the camera in different polarization states are shown as follows. Figure 6 As shown, the wavelength range is from 350 to 1000 nm, and the suitable range is between 400 and 700 nm.

[0035] In this embodiment, in order to improve the spectral resolution of the collected image data, the compressed sensing principle is combined with the sparsity and smoothness prior information to perform spectral super-resolution calculation on the collected image. The convex optimization equation is as follows:

[0036]

[0037] where ||·|| F represents the F norm, ||·||1 represents the 1 norm, Y represents the data captured by the detector, H represents the system acquisition matrix, D represents the dictionary, B represents the corresponding sparse matrix, λ represents the wavelength independent variable, μ represents the coefficient of the sparse constraint term, and γ represents the coefficient of the spectral smoothness constraint term.

[0038] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A high-light-flux biomimetic multi-aperture multi-spectral polarization imaging system, characterized in that: The system comprises a notch filter array, a lens array, and a polarization camera array; the notch filter array comprises a plurality of notch filters; the lens array comprises N camera lenses, the optical axes of each camera lens are parallel, and the focal planes are coplanar; the polarization camera array comprises N polarization cameras, each polarization camera comprises four polarization states of 0°, 45°, 90°, and 135°, and the detector image planes of the polarization cameras are coplanar; parallel light at different angles emitted by a target passes through the notch filters and lenses and forms an image in the detector image plane of the polarization camera; A single notch filter, camera lens, and polarization camera form a single aperture structure, with their central axes aligned. The notch filter array, lens array, and polarization camera array are distributed in a rectangular array; Based on the directly captured multispectral data, the spectral super-resolution calculation of the collected image is performed by combining the principle of compressed sensing with the prior information of sparsity and smoothness. The convex optimization equation is as follows where ||·|| F represents the F norm, ||·||1 represents the 1 norm, Y represents the data captured by the detector, H represents the system acquisition matrix, D represents the dictionary, B represents the corresponding sparse matrix, λ represents the wavelength independent variable, μ represents the coefficient of the sparse constraint term, and γ represents the coefficient of the spectral smoothness constraint term.

2. The high-light-flux biomimetic multi-aperture multi-spectral polarization imaging system according to claim 1, characterized in that: The notch filter adopts the Edmund Notch Filter series, and the central wavelength adopts 405nm, 488nm, 514.5nm, 532nm or 632.8nm.

3. The high-light-flux biomimetic multi-aperture multi-spectral polarization imaging system according to claim 1, characterized in that: The same polarization state of different polarization cameras has different spectral information; Different polarization states of the same polarization camera have the same spectral information.

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