A multi-slit pushbroom hyperspectral imaging system

Abstract

The utility model relates to multi-slit push-scan type hyperspectral imaging system, including front objective lens, multi-slit element, spectrometer imaging subassembly and panchromatic focal plane detector, multi-slit element sets up in the imaging light path of front objective lens, multi-slit element includes rectangular window and multiple parallelly arranged slits, and the rectangular window department sets up filter, spectrometer imaging subassembly respectively receives the light that transmits from rectangular window and slit and handles after, focuses to panchromatic focal plane detector again, panchromatic focal plane detector gathers the light after spectrometer imaging subassembly processing, forms spatial image and spectral data, realizes the errorless splicing and fusion of spectral image according to the position and attitude change in spatial image continuous two frames, obtains the spectral image of high spatial resolution, high spectral resolution. The utility model front lens, the joint design of multi-slit element and spectrometer imaging subassembly obtains the optical system that spectrometer imaging performance is excellent, and the volume is small, and the signal-to-noise ratio is high, and the image acquisition rate is high.

Description

Technical Field

[0001] This utility model relates to the field of spectral imaging technology, and in particular to a multi-slit push-broom hyperspectral imaging system. Background Technology

[0002] Hyperspectral imaging technology is a combination of spectral and imaging technologies, capable of simultaneously acquiring image and spectral information of a target object. It has been widely used in disaster prevention and mitigation, environmental monitoring, land resources, mineral exploration, agriculture and forestry, military and other fields.

[0003] Hyperspectral imaging technology is divided into two categories: snapshot imaging and pushbroom imaging. Snapshot hyperspectral imagers acquire spectral and spatial information simultaneously by capturing area array images, but the spectral and spatial data need to share the same detector channel, thus reducing resolution. Pushbroom imaging spectrometers, on the other hand, combine the excellent performance of high spectral resolution and high spatial resolution, and are being used more and more widely.

[0004] Traditional pushbroom hyperspectral imagers consist of a front objective lens and a beam splitter system, with a single slit between them serving as a field stop. They acquire spectral information of a single band of the target pixel by capturing a single frame, and then acquire spectral data of a band of the scene within the field of view by pushbroom. Traditional single-slit pushbrooms only have one sampling opportunity for the target pixel, resulting in a short gaze time and making them prone to problems such as missing samples and low signal-to-noise ratio. Utility Model Content

[0005] Therefore, the technical problem to be solved by this utility model is to overcome the problem of low light flux and short gaze time in the single-slit push-broom process of the prior art, which leads to low signal-to-noise ratio. It provides a multi-slit push-broom hyperspectral imaging system. Through the joint design of front lens, multi-slit element and beam splitting imaging component, it can obtain an optical system with excellent beam splitting imaging performance, small size, high signal-to-noise ratio and high image acquisition rate.

[0006] To address the aforementioned technical problems, this utility model provides a multi-slit pushbroom hyperspectral imaging system, comprising: a front objective lens, a multi-slit element, a spectroscopic imaging assembly, and a panchromatic focal plane detector; wherein,

[0007] The front objective lens is used to image the light in the target scene;

[0008] A multi-slit element is disposed in the imaging optical path of the front objective lens, and the multi-slit element splits the light into two paths; the multi-slit element includes a rectangular window and multiple parallel slits, and a filter is attached to the rectangular window;

[0009] The beam-splitting imaging component receives and processes the light transmitted through the rectangular window and the slit, and then focuses it onto the panchromatic focal plane detector.

[0010] A panchromatic focal plane detector collects light after it has been processed by a spectroscopic imaging component, forming spatial images and spectral data. Based on the position and attitude changes in two consecutive frames of the spatial image, it performs errorless stitching and fusion of spectral images to obtain spectral images with high spatial resolution and high spectral resolution.

[0011] In one embodiment of this utility model, the front objective lens has the same F-number as the beam splitting imaging component, and the pupil position and size are matched.

[0012] In one embodiment of this utility model, the front objective lens is a transmission objective lens, a reflection objective lens, or a catadioptric objective lens.

[0013] In one embodiment of this utility model, the spectral imaging component includes a concave spherical transmission mirror, a concave spherical reflection mirror, and a planar immersion grating. Part of the light passing through the rectangular window of the multi-slit element is parallelized by the concave spherical transmission mirror, then reflected by the concave spherical reflection mirror to the planar immersion grating, where no dispersion occurs. The light is then focused by the concave spherical transmission mirror and reflected by the concave spherical reflection mirror to a panchromatic focal plane detector to obtain a high-resolution image. Similarly, part of the light passing through the slits of the multi-slit element is parallelized by the concave spherical transmission mirror, then reflected by the concave spherical reflection mirror to the planar immersion grating for dispersion. The light is then focused by the concave spherical transmission mirror and reflected by the concave spherical reflection mirror to a panchromatic focal plane detector to obtain a high-resolution image. Finally, the light is focused by the concave spherical transmission mirror and reflected by the concave spherical reflection mirror to a panchromatic focal plane detector to obtain a spectral image.

[0014] In one embodiment of this utility model, the collimating optical path and the focusing imaging optical path of the spectral imaging component are symmetrically arranged, and both the collimating optical path and the focusing imaging optical path are composed of a concave spherical transmission mirror and a concave spherical reflection mirror.

[0015] In one embodiment of this utility model, the ratio of the radius of curvature of the concave spherical reflector to that of the planar immersion grating is 2.1:1 to 2.4:1.

[0016] In one embodiment of this invention, the spacing between adjacent slits in the multi-slit element ensures that the spectral data of the multi-slit element obtained by the panchromatic focal plane detector do not overlap.

[0017] In one embodiment of this invention, the number of slits in the multi-slit element is at least three, which is used to improve sampling efficiency and increase the number of samplings.

[0018] In one embodiment of this invention, the panchromatic focal plane detector includes an RGB detector with three spectral channels.

[0019] In one embodiment of this utility model, the panchromatic focal plane detector includes a mosaic filter array detector with multiple spectral channels.

[0020] Compared with the prior art, the above-mentioned technical solution of this utility model has the following beneficial effects:

[0021] (1) The multi-slit pushbroom hyperspectral imaging system described in this utility model, through the joint design of the front lens, multi-slit element and beam splitting imaging component, can obtain an optical system with excellent beam splitting imaging performance, small size, high signal-to-noise ratio and high image acquisition rate. By setting multiple slits in the multi-slit element, the target scene can be sampled multiple times in the same frame. This multiple sampling not only improves the sampling efficiency of the system, but also significantly increases the light flux and staring time, thereby improving the signal-to-noise ratio of the system. Compared with the traditional single-slit pushbroom hyperspectral imaging system, this utility model can maintain a higher signal-to-noise ratio without losing image resolution and working efficiency, and is especially suitable for imaging under low light conditions.

[0022] (2) The rectangular window design of the multi-slit element can ensure that the light does not disperse when it passes through the beam splitter and finally reaches the focal plane detector to obtain a high spatial resolution image. By comparing the high spatial resolution images between adjacent frames, the pose change information is obtained to assist in the stitching of the slit images. No external equipment is needed to obtain the pose information. The structure is simple, lightweight and easy to use, and the stitching accuracy is high. Attached Figure Description

[0023] To make the content of this utility model easier to understand, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0024] Figure 1 This is the optical path diagram of the multi-slit element hyperspectral imaging system of this utility model;

[0025] Figure 2 This is a schematic diagram of the multi-slit element of this utility model;

[0026] Figure 3 This is a schematic diagram of the dispersive spectrum of the multi-slit element acquired by the panchromatic focal plane detector of this utility model.

[0027] Explanation of reference numerals in the accompanying drawings: 1. Front objective lens; 2. Multi-slit element; 3. Spectroscopic imaging assembly; 3.1. Concave spherical transmission mirror; 3.2. Concave spherical reflection mirror; 3.3. Planar immersion grating; 4. Panchromatic focal plane detector. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments are not intended to limit the present invention.

[0029] Reference Figure 1 and 2 As shown, this utility model provides a multi-slit pushbroom hyperspectral imaging system, including: a front objective lens 1, a multi-slit element 2, a spectroscopic imaging component 3, and a panchromatic focal plane detector 4.

[0030] The multi-slit element 2 includes a rectangular window and several parallel slits; a filter is provided at the light outlet of the rectangular window;

[0031] The beam-splitting imaging component 3 includes a concave spherical transmission mirror 3.1, a concave spherical reflection mirror 3.2, and a planar immersion grating 3.3. Light from the target scene is imaged after passing through the front objective lens 1. In its imaging optical path, the light passing through the rectangular window of the multi-slit element 2 is parallelized by the concave spherical transmission mirror 3.1, and then reflected by the concave spherical reflection mirror 3.2 to the planar immersion grating 3.3. At this point, no dispersion occurs. The light is then focused by the concave spherical transmission mirror 3.1 and reflected by the concave spherical reflection mirror 3.2 to the panchromatic focal plane detector 4 to obtain a high-resolution spatial image. Light passing through multiple slits on the multi-slit element 2 is parallelized by the concave spherical transmission mirror 3.1, then reflected by the concave spherical reflection mirror 3.2 to the planar immersion grating 3.3 for dispersion. The light is then focused by the concave spherical transmission mirror 3.1 and reflected by the concave spherical reflection mirror 3.2 to the panchromatic focal plane detector 4 to obtain a high-resolution image. Finally, the light is focused by the concave spherical transmission mirror 3.1 and reflected by the concave spherical reflection mirror 3.2 to the panchromatic focal plane detector 4 to obtain a spectral image.

[0032] In the slit transmission path, multiple slits in the multi-slit element 2 perform strip sampling on the image plane of the front objective lens 1. A certain gap is left between the sampling strips. The spectroscopic imaging component 3 disperses the polychromatic light input from each slit to the panchromatic focal plane detector 4. The dispersive spectra of each slit are recorded independently without overlap. The hyperspectral data of each slit can be extracted by the spectral reconstruction algorithm to obtain the hyperspectral data of the scene target.

[0033] The rectangular window in the multi-slit element 2 provides an optical path that does not pass through the multi-slit element 2. After the light passes through the front objective lens 1 for imaging, part of the light passes through the slits of the multi-slit element 2 for spectral dispersion and sampling, while the other part of the light passes through the rectangular window and directly enters the spectral imaging assembly 3. This design enables the system to perform two functions simultaneously in the same optical path: one is to perform hyperspectral imaging through the multi-slit element; the other is that the light passing through the rectangular window does not undergo chromatic dispersion when it passes through the spectral imaging assembly 3, and finally reaches the panchromatic focal plane detector 4 to obtain a high spatial resolution image.

[0034] The rectangular window design enables the acquisition of high-resolution spatial images while simultaneously acquiring hyperspectral data. By comparing high spatial resolution images between adjacent frames, pose change information is obtained to assist in stitching slit images. Pose information can be obtained without the need for external devices. The structure is simple, lightweight, easy to use, and has high stitching accuracy.

[0035] In the above scheme, simultaneous exposure and image acquisition at the same frame rate can be achieved by capturing a single frame. The panchromatic focal plane detector 4 simultaneously acquires the spatial image and spectral data of the target area. Based on the position and attitude changes in two consecutive frames of the spatial image, an image fusion algorithm is run to achieve errorless stitching and fusion of the spectral images, resulting in a spectral image with high spatial resolution and high spectral resolution.

[0036] In this embodiment, the front objective lens 1 can be a transmission objective lens, a reflection objective lens, or a catadioptric objective lens.

[0037] It should be noted that the front objective lens 1 and the beam-splitting imaging component 3 have the same F-number, and their pupil positions and sizes are matched. This matching pupil and consistent F-number design allows for seamless integration of the front objective lens 1 and the beam-splitting imaging component 3, simplifying the optical design of the system and improving its stability and reliability.

[0038] In the above scheme, the collimating optical path and the focusing imaging optical path of the beam-splitting imaging component 3 are symmetrically arranged, and both the collimating optical path and the focusing imaging optical path are composed of a concave spherical transmission mirror 3.1 and a concave spherical reflection mirror 3.2. The collimation and focusing functions are achieved through the same set of components, which reduces the number of optical components and the size of the imaging system.

[0039] In this embodiment, the ratio of the radius of curvature of the concave spherical mirror 3.1 to the planar immersion grating 3.2 is 2.1:1 to 2.4:1.

[0040] Preferably, the panchromatic focal plane detector 4 can be an RGB detector with three spectral channels, or a mosaic filter array detector with multiple spectral channels.

[0041] In this embodiment, the panchromatic focal plane detector 4 has a resolution of 1936×1216, and the ratio of transmitted to reflected light intensity of the beam splitter is 5:1.

[0042] In this embodiment, the multi-slit element 2 has at least three slits to improve sampling efficiency and increase the number of samplings. The parameters of the multi-slit element are shown in Table 1.

[0043] Table 1

[0044]

[0045] In practical applications, the number and spacing of the slits in the multi-slit element 2 can be adjusted according to the spectral characteristics and spatial resolution requirements of the target scene.

[0046] It is worth noting that when actually setting the slit spacing, the slit spacing needs to ensure that the spectral data of the multi-slit elements obtained by the multispectral focal plane detector do not overlap.

[0047] Preferably, the front objective lens 1 is a transmission-type double Gaussian objective lens, comprising a 7-element structure in 5 groups; the collimating lens group and focusing lens group in the beam-splitting imaging assembly 3 are symmetrically placed with the same optical system, each comprising a 4-element structure in 4 groups, and their optical system parameters are shown in Table 2:

[0048] Table 2

[0049]

[0050] The multi-slit hyperspectral imaging system provided by the embodiment based on the above structure has the following key performance parameters:

[0051] Spectral range: 1000-2500nm; covering the near-infrared to short-wave infrared region, suitable for a variety of hyperspectral imaging applications, such as mineral exploration, environmental monitoring and agricultural analysis.

[0052] The system's F-number is 4.7, ensuring both high light throughput and imaging brightness while maintaining a compact design and high resolution.

[0053] Field of view: 45°; provides a wide imaging range, suitable for rapid scanning of large-area targets.

[0054] Front objective lens focal length: 30mm; combined with F-number design, the system's imaging quality and spectral resolution are optimized.

[0055] Image resolution: 6 megapixels; ensuring high-definition spatial images, facilitating subsequent spectral analysis and image processing.

[0056] Spectral resolution: 7nm. Provides high-precision spectral information, effectively distinguishing the spectral characteristics of different substances.

[0057] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. A multi-slit pushbroom hyperspectral imaging system, characterized in that, include: The components include a front objective lens, a multi-slit element, a beam-splitting imaging assembly, and a panchromatic focal plane detector; among them, The front objective lens is used to image the light in the target scene; A multi-slit element is disposed in the imaging optical path of the front objective lens; the multi-slit element includes a rectangular window and multiple parallel slits, and a filter is attached to the rectangular window; The beam-splitting imaging component receives and processes the light transmitted through the rectangular window and the slit, and then focuses it onto the panchromatic focal plane detector. A panchromatic focal plane detector collects light after it has been processed by a spectroscopic imaging component, forming spatial images and spectral data. Based on the position and attitude changes in two consecutive frames of the spatial image, it performs errorless stitching and fusion of spectral images to obtain spectral images with high spatial resolution and high spectral resolution.

2. The multi-slit pushbroom hyperspectral imaging system according to claim 1, characterized in that, The front objective lens has the same F-number as the beam splitting imaging component, and the pupil position and size are matched.

3. The multi-slit push-broom hyperspectral imaging system according to claim 2, characterized in that, The front objective lens is one of a transmission objective lens, a reflection objective lens, or a catadioptric objective lens.

4. The multi-slit pushbroom hyperspectral imaging system according to claim 1, characterized in that, The spectral imaging assembly includes a concave spherical transmission mirror, a concave spherical reflection mirror, and a planar immersion grating. A portion of the light passing through the rectangular window of the multi-slit element is parallelized by the concave spherical transmission mirror, then reflected by the concave spherical reflection mirror to the planar immersion grating, where no dispersion occurs. The light is then focused by the concave spherical transmission mirror and reflected by the concave spherical reflection mirror to a panchromatic focal plane detector to obtain a high-resolution image. A portion of the light passing through the slits of the multi-slit element is parallelized by the concave spherical transmission mirror, then reflected by the concave spherical reflection mirror to the planar immersion grating for dispersion. The light is then focused by the concave spherical transmission mirror and reflected by the concave spherical reflection mirror to a panchromatic focal plane detector to obtain a high-resolution image. Finally, the light is focused by the concave spherical transmission mirror and reflected by the concave spherical reflection mirror to a panchromatic focal plane detector to obtain a spectral image.

5. The multi-slit pushbroom hyperspectral imaging system according to claim 4, characterized in that, The collimating optical path and the focusing imaging optical path of the spectral imaging component are symmetrical, and both the collimating optical path and the focusing imaging optical path are composed of the same concave spherical transmission mirror and concave spherical reflection mirror.

6. The multi-slit pushbroom hyperspectral imaging system according to claim 4, characterized in that, The ratio of the radius of curvature of the concave spherical mirror to that of the planar immersion grating is 2.1:1 to 2.4:

1.

7. The multi-slit pushbroom hyperspectral imaging system according to claim 1, characterized in that, The spacing between adjacent slits in the multi-slit element ensures that the spectral data obtained by the panchromatic focal plane detector do not overlap.

8. The multi-slit pushbroom hyperspectral imaging system according to claim 6, characterized in that, The multi-slit element has at least three slits to improve sampling efficiency and increase the number of samplings.

9. The multi-slit pushbroom hyperspectral imaging system according to claim 1, characterized in that, Its features are: The panchromatic focal plane detector includes an RGB detector with three spectral channels.

10. The multi-slit pushbroom hyperspectral imaging system according to claim 1, characterized in that, The panchromatic focal plane detector includes a mosaic filter array detector with multiple spectral channels.

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