Multi-spectral imaging system based on variable filter area adjustment

Abstract

The invention discloses a multispectral imaging system based on variable filter area adjustment. The multispectral imaging system comprises a lens, a variable filter, a detector and computing equipment, the lens comprises a front-group lens and a rear-group lens; the front group of lenses converges and collimates target light information to enable the target light information to be incident on the variable filter; the variable filter performs energy coding on each channel spectral component in the incident target light information by adjusting the light passing area of each spectral channel for multiple times, and outputs the target light information after each modulation; the rear group of lenses collect the information of the target light after each modulation to enable the information to be incident on the detector; the detector detects light intensity information of each time and sends the light intensity information to the computing device; and the computing device linearly decodes the light intensity information obtained for multiple times, and recovers to obtain the spectral component of the target under each wavelength. According to the invention, the problems of low light energy utilization rate, low signal-to-noise ratio, mutual restriction of spectrum channel number and spatial resolution and the like can be solved.

Description

Technical Field

[0001] The invention belongs to the technical field of multispectral imaging, and in particular relates to a multispectral imaging system based on variable filter area adjustment. Background Art

[0002] At present, multispectral imaging has been widely used in various fields, such as agriculture, medicine, industry, cultural relics identification and document protection.

[0003] In view of the current multispectral imaging technology, in one existing design, Ethan Schonbrun et al. proposed a polarization coded color (PEC) camera system, such as Figure 1 As shown in the figure, by combining a pixelated polarizer with a chiral dispersion element, the color is encoded into a linear polarization state and read in a single exposure. Its structure includes a pixelated polarizer composed of four linear micropolarizers and a chiral disperser. The camera can capture three-color images from visible light to near-infrared wavelengths, can be photographed under artificial lighting and daylight, is suitable for single-frame acquisition of fast-moving objects, and can also be used in imaging systems and microscopes to quantify hemoglobin in biological samples. However, the number of spectral channels that the camera can detect is extremely limited. When the pixelated polarizer exceeds three states, the number of resolvable spectral channels cannot be increased, and it is difficult to retrieve four spectra independently in a single exposure. In general, the PEC camera has advantages such as reconfigurable spectral response, but its spectral detection capability needs to be further improved.

[0004] In another existing design, the SHUJIONO team proposed a snapshot multispectral imaging technology, such as Figure 2 As shown in the figure, this technology combines a set of imaging lenses with multispectral filters and polarization filters with a pixel-level color polarization image sensor. The image sensor can obtain polarization color coded images mixed with multispectral images, and then the multispectral polarization image of the target can be reconstructed through the crosstalk elimination decoding algorithm. This technology only needs to expose the image sensor once to obtain the multispectral information of the target, but due to the limited number of encoding times and encoding parameters, the encoding ability is not strong, resulting in a limited number of spectral channels for the final decoding and reconstruction, which cannot exceed nine, which greatly limits the system's ability to detect the spectral details of the target. This technology requires the use of a color polarization image sensor to obtain stronger information decoding capabilities, and requires that the image formed by each point on the target after passing through the imaging lens must correspond to a group of RGB color polarization pixel blocks of the color polarization image sensor, that is, 16 sub-pixels (4*4) of the color polarization detector correspond to one pixel of the black and white detector. Therefore, the reconstructed multispectral polarization image has low spatial resolution, which is not conducive to accurately displaying the detailed features of the target.

[0005] At present, most traditional multispectral imaging technologies use multispectral imaging methods based on filter wheels, acousto-optic tunable filters or liquid crystal tunable filters. This type of system collects the image of the target in a single spectral channel during each measurement, and realizes the image acquisition of the target in different spectral channels by switching the spectral channels of the acousto-optic tunable filter or the liquid crystal tunable filter, or rotating the filter wheel. Since this method can only measure the image of the target in a single spectral channel each time, the utilization rate of the incident light energy is not high, especially for the spectral band with a relatively low spectral response rate of the detector (such as near blue light), the signal-to-noise ratio of the acquired spectral image is relatively low.

[0006] With the development of micro-electromechanical system technology, multi-channel spectral filter pixel array chips that can be integrated with detectors at the pixel level have emerged. A large number of micro-nano-level spectral filter units are integrated on the chip, which can simultaneously image multiple spectral channels. Currently, there are specifications such as 2*2 four-channel, 3*3 nine-channel, and 4*4 sixteen-channel. However, this method requires that the multi-channel spectral filter unit be regarded as a macro-pixel and correspond to multiple pixels on the detector. One macro-pixel corresponds to one object point. This will lead to a mutual restriction between the number of spectral channels and the spatial resolution. The more spectral channels there are, the more detector pixels the macro-pixel contains, and the lower the spatial resolution.

[0007] In summary, the existing multispectral imaging technology has various limitations, such as low light energy utilization, low signal-to-noise ratio, and mutual constraints between the number of spectral channels and spatial resolution, which affect the development and application of multispectral imaging technology. Summary of the invention

[0008] In order to solve the above problems existing in the prior art, the present invention provides a multi-spectral imaging system based on variable filter area adjustment. The technical problem to be solved by the present invention is achieved by the following technical solutions:

[0009] A multi-spectral imaging system based on variable filter area adjustment comprises: a lens, a variable filter, a detector and a computing device; the lens comprises a front lens group and a rear lens group, which are respectively arranged in front of and behind an aperture stop, and each comprises a plurality of lenses; the variable filter is a multi-channel narrow-band filter, which is arranged at the aperture stop of the lens, and the light passing area and the gating wavelength of each spectral channel are controllable; the detector is arranged at the image plane of the lens;

[0010] The front lens group is used to converge and collimate the target light information so that it is incident on the variable filter;

[0011] The variable filter is used to perform energy encoding on the spectral components of each channel in the incident target light information by adjusting the light transmission area of ​​each spectral channel multiple times, and output the target light information after each modulation;

[0012] The rear lens group is used to collect the target light information after each modulation and make it incident on the detector;

[0013] The detector is used to detect the intensity information of each light focused by the rear lens group and send it to the computing device;

[0014] The computing device is used to linearly decode the light intensity information obtained multiple times, and restore the spectral components of the target at each wavelength.

[0015] In one embodiment of the present invention, the variable filter completes the adjustment of the light transmission area of ​​each spectral channel in multiple modulations according to a pre-set light transmission area matrix; wherein the number of rows of the light transmission area matrix represents the number of modulations, and each element in each row is the light transmission area of ​​each spectral channel in the corresponding modulation; the light transmission area matrix is ​​a full rank matrix.

[0016] In one embodiment of the present invention, in any modulation of the variable filter, each spectral channel uses its light passing area, transmittance and selection center wavelength to perform energy encoding on the spectral components belonging to the channel in the incident target light information.

[0017] In one embodiment of the present invention, for any modulation of the variable filter, the light intensity information detected by the detector is the sum of the energy encoding results of all spectral channels in the modulation of the variable filter, which is expressed as:

[0018]

[0019] Wherein, O(x, y) is the light emitted from a point (x, y) on the target; the variable filter has n spectral channels, and the selection center wavelength of the i-th spectral channel is λ i , the transmittance is T i (λ), the light passing area is S i , S i T i O(x,y,λ i ) is the energy encoding result of the i-th spectral channel, i = 1~n; O(x * ,y * ) is the light intensity information detected by the detector.

[0020] In one embodiment of the present invention, the process of the computing device linearly decoding the light intensity information obtained multiple times to restore the spectral components of the target at each wavelength includes:

[0021] Obtaining a light intensity information matrix according to the light intensity information obtained multiple times;

[0022] Calculate the product of the inverse matrix of the light-transmitting area matrix and the light intensity information matrix to obtain a first matrix;

[0023] The components in the first matrix are divided by the transmittance of the corresponding spectral channel to obtain the spectral components of the target at the corresponding wavelength.

[0024] In one embodiment of the present invention, obtaining a light intensity information matrix according to the light intensity information obtained multiple times includes:

[0025] According to the light intensity information obtained by n modulations, the equation group is obtained as follows:

[0026]

[0027] Rewriting the equations into matrix form, we get the light intensity information matrix, which is expressed as:

[0028]

[0029] Wherein, O(x, y) is the light emitted from a point (x, y) on the target; the variable filter has n spectral channels, and the selection center wavelength of the i-th spectral channel is λ i , the transmittance is T i (λ), the light passing area is S i , S i T i O(x,y,λ i ) is the energy encoding result of the i-th spectral channel, i=1~n; is the light-transmitting area matrix; i (x * ,y * ) is the light intensity information detected by the detector after the i-th modulation.

[0030] In one embodiment of the present invention, the first matrix is ​​expressed as:

[0031]

[0032] The spectral components of the target at each wavelength are expressed as:

[0033] O(x,y,λ i )=T i O(x,y,λ i ) / T i ;

[0034] Among them, O(x,y,λ i ) represents the light O(x,y) emitted from a point (x,y) on the target at a wavelength λ i The spectral components below.

[0035] In one embodiment of the present invention, the detector is a black and white detector.

[0036] The present invention proposes a multi-spectral imaging system based on variable filter area adjustment, which performs multiple energy encoding on the spectral components of each channel in the incident target light by adjusting the light transmission area of ​​each spectral channel on the filter multiple times, and then linearly decodes the obtained multiple groups of spectral mixed information to restore multiple spectral components of the target. Compared with the prior art, the present invention has the following effects:

[0037] 1. Higher energy efficiency and higher signal-to-noise ratio

[0038] The present invention can encode and decode spectral information by adjusting the light-passing area of ​​different channels of the variable filter, and can efficiently utilize energy. Specifically, by reasonably adjusting the light-passing area of ​​different channels of the variable filter, light of different wavelengths can be effectively passed and modulated as needed, thereby improving the energy utilization efficiency of the entire system. At the same time, the present invention can also improve the signal-to-noise ratio. Through a unique encoding and decoding method based on variable filter area adjustment, it can reduce noise interference and improve signal quality when processing spectral information. For example, by reasonably controlling the light-passing area of ​​different channels of the variable filter, the light information received by the detector can be made purer, unnecessary noise components can be reduced, and the signal-to-noise ratio can be improved. A better multi-spectral imaging effect can be achieved.

[0039] 2. The number of spectral channels and spatial resolution have no mutual constraints

[0040] The spatial resolution of the present invention is not restricted by the number of spectral channels. There is no multi-channel spectral filter pixel array chip for pixel-level integration in front of the detector of the system, and the spatial resolution is only affected by the detector and is not mutually restricted by the number of spectral channels.

[0041] 3. The number of spectral channels can be flexibly adjusted

[0042] The present invention has greater flexibility in the number of spectral channels. By adjusting the light-passing areas of different channels of the variable filter, the number of spectral channels can be flexibly adjusted according to actual needs without being limited to fixed encoding times and encoding parameters, thereby being able to better meet different requirements for target spectral detail detection.

[0043] 4. The system structure is simpler

[0044] The present invention mainly constructs a system based on three main components: a lens, a variable filter and a detector. The structure is more concise and clear, which reduces the complexity and cost of the system and also improves the stability and reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1A schematic diagram of an existing polarization coded color (PEC) camera system;

[0046] Figure 2 It is a schematic diagram of the structure of an existing snapshot multi-spectral imaging system;

[0047] Figure 3 A schematic diagram of the structure of a multi-spectral imaging system based on variable filter area adjustment provided by an embodiment of the present invention;

[0048] Figure 4 A schematic diagram for understanding the variable filter structure provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0049] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0050] The embodiment of the present invention provides a multi-spectral imaging system based on variable filter area adjustment, such as Figure 3 As shown, it may include:

[0051] A lens, a variable filter, a detector and a computing device; the lens comprises a front lens group and a rear lens group, which are respectively arranged in front of and behind the aperture stop, and each comprises a plurality of lenses; the variable filter is a multi-channel narrow-band filter, which is arranged at the aperture stop of the lens, and the light passing area and the selected wavelength of each spectral channel are controllable; the detector is arranged at the image plane of the lens;

[0052] The front lens group is used to converge and collimate the target light information so that it is incident on the variable filter;

[0053] The variable filter is used to perform energy encoding on the spectral components of each channel in the incident target light information by adjusting the light transmission area of ​​each spectral channel multiple times, and output the target light information after each modulation;

[0054] The rear lens group is used to collect the target light information after each modulation and make it incident on the detector;

[0055] The detector is used to detect the intensity information of each light focused by the rear lens group and send it to the computing device;

[0056] The computing device is used to linearly decode the light intensity information obtained multiple times, and restore the spectral components of the target at each wavelength.

[0057] In the embodiment of the present invention, the structural design of the multi-spectral imaging system based on variable filter area adjustment ensures the effective transmission and processing of optical information in the system, and lays a foundation for realizing efficient spectral encoding and decoding.

[0058] In the embodiment of the present invention, the target may be any object. Figure 3 The boxes contain the components of the multi-spectral imaging system based on variable filter area adjustment. It mainly includes lenses, variable filters, detectors and computing devices. Taking the position of the aperture diaphragm as the boundary, the lens is further divided into a front lens group and a rear lens group. The front lens group is placed in front of the aperture diaphragm, and the rear lens group is placed behind the aperture diaphragm. The front lens group and the rear lens group are both composed of multiple lenses. For the front lens group and the rear lens group, the multiple lenses therein can be coaxially arranged, and the size and spacing of each lens in the front lens group and the rear lens group can be set as needed. In the embodiment of the present invention, there is no restriction on the lens type in the front lens group and the rear lens group, for example, it can be a spherical lens or an aspherical lens.

[0059] The front lens is responsible for converging and collimating the target light information so that it is incident on the variable filter.

[0060] The variable filter is placed at the aperture stop of the lens. It is a multi-channel narrowband filter with controllable light passing area and gating wavelength of different channels. Its controllable light passing channel size and gating wavelength enable the selective passage and modulation of light of different wavelengths as needed. By reasonably dividing the spectral channels, each spectral channel has a specific gating center wavelength, transmittance and light passing area, thereby realizing the fine encoding of spectral information. In use, the variable filter is divided into n spectral channels, and the gating center wavelength of each spectral channel is λ i , (i = 1 ~ n), the transmittance is T i (λ), the area of ​​the clear aperture is S i For an illustration of the variable filter structure, see Figure 4 The variable filter can change the light passing area of ​​different channels and the selected wavelength by means of voltage regulation or other means, or by using some new electrically controlled materials. Any method that can change the light passing area of ​​each spectral channel of the filter can be included in the protection scope of the present invention, and is not limited here.

[0061] The variable filter will perform multiple modulations on the incident target light information. Specifically, the variable filter completes the adjustment of the light transmission area of ​​each spectral channel in the multiple modulations according to a preset light transmission area matrix; the light transmission area matrix is ​​a full rank matrix.

[0062] In the embodiment of the present invention, the light-transmitting area matrix can be pre-designed according to the requirements of the full-rank matrix and the number of spectral channels n, and determined for subsequent use. In the embodiment of the present invention, S represents the light-transmitting area matrix, which is specifically expressed as:

[0063]

[0064] The number of rows of the light transmission area matrix represents the number of modulations, and each element in each row is the light transmission area of ​​each spectral channel in the corresponding modulation.

[0065] Specifically, in any modulation of the variable filter, the light passing area of ​​each spectral channel is set according to the value of each element of the corresponding row in the light passing area matrix. Each spectral channel uses its light passing area, transmittance and selection center wavelength to encode the energy of the spectral component belonging to the channel in the incident target light information.

[0066] Assuming that the light emitted from a point (x, y) on the target is O(x, y), taking the i-th spectral channel as an example, the encoding result after energy encoding can be expressed as S i T i O(x,y,λ i ). After this modulation, the encoding results output by all spectral channels are combined to obtain the target light information after this modulation;

[0067] The rear lens group is used to collect the target light information after each modulation and make it incident on the detector;

[0068] The detector is used to detect the intensity information of each light focused by the rear lens group and send it to the computing device; in an optional implementation, the detector is a black and white detector, which can be implemented using existing commercial products.

[0069] The computing device is used to linearly decode the light intensity information obtained multiple times, and restore the spectral components of the target at each wavelength.

[0070] In the embodiment of the present invention, the computing device may be a device or component with data processing capability, such as a computer.

[0071] For ease of understanding, the following combination Figure 4 , the processing after the detector is explained.

[0072] The spectral curve near the central wavelength of each spectral channel is approximated as a rectangular function. For any modulation of the variable filter, the light intensity information detected by the detector is the sum of the energy encoding results of all spectral channels in the modulation of the variable filter, which can be expressed as:

[0073]

[0074] Wherein, O(x, y) is the light emitted from a point (x, y) on the target; the variable filter has n spectral channels, and the selection center wavelength of the i-th spectral channel is λ i , the transmittance is T i(λ), the light passing area is S i , S i T i O(x,y,λ i ) is the energy encoding result of the i-th spectral channel, O(x,y,λ i ) is the light at (x, y) under the selected central wavelength λi, i=1~n; O(x*, y*) is the light intensity information detected by the detector.

[0075] The process in which the computing device linearly decodes the light intensity information obtained multiple times to restore the spectral components of the target at each wavelength includes:

[0076] 1) obtaining a light intensity information matrix according to the light intensity information obtained multiple times;

[0077] Specifically, according to the light intensity information obtained by n modulations, the equation group is obtained as follows:

[0078]

[0079] Rewriting the equations into matrix form, we get the light intensity information matrix, which is expressed as:

[0080]

[0081] in, is the light-transmitting area matrix.

[0082] 2) calculating the inverse matrix of the light-transmitting area matrix and multiplying it by the light intensity information matrix to obtain a first matrix;

[0083] Specifically, the first matrix is ​​expressed as:

[0084]

[0085] The left side of the equal sign is the first matrix, in which each row corresponds to a spectral channel, that is, corresponds to a selection center wavelength.

[0086] 3) Dividing the components in the first matrix by the transmittance of the corresponding spectral channel respectively, to obtain the spectral components of the target at the corresponding wavelength.

[0087] Among them, the spectral component of the target at each wavelength is expressed as:

[0088] O(x,y,λ i )=T i O(x,y,λ i ) / T i ;

[0089] Among them, O(x,y,λ i) represents the light O(x,y) emitted from a point (x,y) on the target at a wavelength λ i The spectral components below.

[0090] In an embodiment of the present invention, a variable filter encodes light information at different wavelengths by changing its area. Specifically, when light emitted from a point on the target enters the system, it is first converged and collimated by the front lens group, and then reaches the variable filter. The variable filter is divided into multiple spectral channels, each of which has its specific selection center wavelength, transmittance and light-passing area. The spectral curve near the center wavelength of each spectral channel is approximated as a rectangular function, and by changing the size of the light-passing area of ​​different spectral channels, multiple modulation shots can obtain different combinations of light information. This method of encoding light information at different wavelengths by changing the area enables the spectral information to be encoded and recorded in a unique way, making it possible for subsequent decoding and restoration of the spectral information.

[0091] For example, when changing the light passing area of ​​different channels, the energy of light of different wavelengths passing through will change, and the light intensity received on the detector will also change accordingly. By taking multiple shots of light information under different area settings, a relationship model between spectral information and light passing area can be established, thereby achieving effective encoding of spectral information.

[0092] Based on the above encoding process, during decoding, the original spectral information can be restored by analyzing and processing the light information received by the detector and using the established relationship model between the spectral information and the light-transmitting area. Specifically, the light information received on the detector is processed according to a certain algorithm and mathematical model, for example, the light information obtained by multiple shots is combined into a set of equations and rewritten into a matrix form. On the premise that the light-transmitting area matrix is ​​a full-rank matrix, the input light of each channel can be further represented, thereby restoring the components of light emitted from a point on the target at different wavelengths, and finally realizing the interpretation of the entire spectral information.

[0093] This light information interpretation idea is the key to the accurate acquisition of spectral information by the multi-spectral imaging system based on variable filter area adjustment. It ensures that the system can effectively restore the original spectral information from the encoded light information, thereby achieving accurate spectral imaging of the target.

[0094] In summary, the present invention proposes a multispectral imaging system based on variable filter area adjustment. By adjusting the light-passing area of ​​each spectral channel on the filter multiple times, the spectral components of each channel in the incident target light are energy encoded multiple times, and then the obtained multiple groups of spectral mixing information are linearly decoded to restore the multiple spectral components of the target.

[0095] Compared with the prior art, the present invention has the following effects:

[0096] 1. Higher energy efficiency and higher signal-to-noise ratio

[0097] The present invention can encode and decode spectral information by adjusting the light-passing area of ​​different channels of the variable filter, and can efficiently utilize energy. Specifically, by reasonably adjusting the light-passing area of ​​different channels of the variable filter, light of different wavelengths can be effectively passed and modulated as needed, thereby improving the energy utilization efficiency of the entire system. At the same time, the present invention can also improve the signal-to-noise ratio. Through a unique encoding and decoding method based on variable filter area adjustment, it can reduce noise interference and improve signal quality when processing spectral information. For example, by reasonably controlling the light-passing area of ​​different channels of the variable filter, the light information received by the detector can be made purer, unnecessary noise components can be reduced, and the signal-to-noise ratio can be improved. A better multi-spectral imaging effect can be achieved.

[0098] 2. The number of spectral channels and spatial resolution have no mutual constraints

[0099] The spatial resolution of the present invention is not restricted by the number of spectral channels. There is no multi-channel spectral filter pixel array chip for pixel-level integration in front of the detector of the system, and the spatial resolution is only affected by the detector and is not mutually restricted by the number of spectral channels.

[0100] 3. The number of spectral channels can be flexibly adjusted

[0101] The present invention has greater flexibility in the number of spectral channels. By adjusting the light-passing areas of different channels of the variable filter, the number of spectral channels can be flexibly adjusted according to actual needs without being limited to fixed encoding times and encoding parameters, thereby being able to better meet different requirements for target spectral detail detection.

[0102] 4. The system structure is simpler

[0103] The present invention mainly constructs a system based on three main components: a lens, a variable filter and a detector. The structure is more concise and clear, which reduces the complexity and cost of the system and also improves the stability and reliability of the system.

[0104] It should be noted that, in the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0105] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0106] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification.

[0107] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A multispectral imaging system based on variable filter area adjustment, characterized in that: include: A lens, a variable filter, a detector and a computing device; the lens comprises a front lens group and a rear lens group, which are respectively arranged in front of and behind the aperture stop, and each comprises a plurality of lenses; the variable filter is a multi-channel narrow-band filter, which is arranged at the aperture stop of the lens, and the light passing area and the selected wavelength of each spectral channel are controllable; the detector is arranged at the image plane of the lens; The front lens group is used to converge and collimate the target light information so that it is incident on the variable filter; The variable filter is used to perform energy encoding on the spectral components of each channel in the incident target light information by adjusting the light transmission area of ​​each spectral channel multiple times, and output the target light information after each modulation; The rear lens group is used to collect the target light information after each modulation and make it incident on the detector; The detector is used to detect the intensity information of each light focused by the rear lens group and send it to the computing device; The computing device is used to linearly decode the light intensity information obtained multiple times, and restore the spectral components of the target at each wavelength.

2. The multi-spectral imaging system based on variable filter area adjustment according to claim 1, characterized in that: The variable filter completes the adjustment of the light transmission area of ​​each spectral channel in multiple modulations according to a preset light transmission area matrix; wherein the number of rows of the light transmission area matrix represents the number of modulations, and each element in each row is the light transmission area of ​​each spectral channel in the corresponding modulation; the light transmission area matrix is ​​a full rank matrix.

3. The multi-spectral imaging system based on variable filter area adjustment according to claim 2, characterized in that: In any modulation of the variable filter, each spectral channel uses its light-passing area, transmittance and selection center wavelength to perform energy encoding on the spectral components belonging to the channel in the incident target light information.

4. The multi-spectral imaging system based on variable filter area adjustment according to claim 3, characterized in that: For any modulation of the variable filter, the light intensity information detected by the detector is the sum of the energy encoding results of all spectral channels in the modulation of the variable filter, which can be expressed as: Wherein, O(x, y) is the light emitted from a point (x, y) on the target; the variable filter has n spectral channels, and the selection center wavelength of the i-th spectral channel is λ i , the transmittance is T i (λ), the light-transmitting area is Si, SiTiO(x, y, λi) is the energy encoding result of the i-th spectral channel, i=1~n; O(x*, y*) is the light intensity information detected by the detector.

5. The multi-spectral imaging system based on variable filter area adjustment according to claim 1 or 4, characterized in that: The process of the computing device linearly decoding the light intensity information obtained multiple times to restore the spectral components of the target at each wavelength includes: Obtaining a light intensity information matrix according to the light intensity information obtained multiple times; Calculate the product of the inverse matrix of the light-transmitting area matrix and the light intensity information matrix to obtain a first matrix; The components in the first matrix are divided by the transmittance of the corresponding spectral channel to obtain the spectral components of the target at the corresponding wavelength.

6. The multi-spectral imaging system based on variable filter area adjustment according to claim 5, characterized in that: The step of obtaining a light intensity information matrix according to the light intensity information obtained for multiple times includes: According to the light intensity information obtained by n modulations, the equation group is obtained as follows: Rewriting the equations into matrix form, we get the light intensity information matrix, which is expressed as: Wherein, O(x, y) is the light emitted from a point (x, y) on the target; the variable filter has n spectral channels, and the selection center wavelength of the i-th spectral channel is λ i , the transmittance is T i (λ), the light passing area is S i , S i T i O(x,y,λ i ) is the energy encoding result of the i-th spectral channel, i=1~n; is the light-transmitting area matrix; i (x * ,y * ) is the light intensity information detected by the detector after the i-th modulation.

7. The multi-spectral imaging system based on variable filter area adjustment according to claim 6, characterized in that: The first matrix is ​​expressed as: The spectral components of the target at each wavelength are expressed as: O(x,y,λ i )=T i O(x,y,λ i ) / T i ; Among them, O(x,y,λ i ) represents the light O(x,y) emitted from a point (x,y) on the target at a wavelength λ i The spectral components below.

8. The multi-spectral imaging system based on variable filter area adjustment according to claim 1, characterized in that: The detector is a black and white detector.

Images