A handheld multispectral imager

Abstract

The application provides a handheld multispectral imager, which comprises an image sensor, and the image sensor comprises a pixel photosensitive unit, a first matching layer and a light splitting structure; the pixel photosensitive unit is used for realizing image acquisition and data readout; the first matching layer is integrally deposited and grown on the pixel photosensitive unit, and is used for improving the central wavelength transmittance of the image sensor; the light splitting structure comprises a plurality of periods which are periodically distributed, each period comprises a narrow-band filter film which is integrally deposited and grown on the first matching layer, and the narrow-band filter film is used for realizing tunable central wavelength in a required waveband; and the narrow-band filter film comprises a plurality of FP cavity structures which are mosaically distributed. The technical scheme of the application is used to solve the technical problems of low central wavelength transmittance and low quantum efficiency of the image sensor in the prior art.

Description

Technical Field

[0001] This invention relates to the field of spectral imaging technology, and more particularly to a handheld multispectral imager. Background Technology

[0002] Hyperspectral Imaging (HSI) systems can acquire three-dimensional spectral images with "image-spectrum integration" characteristics, which are composed of two-dimensional spatial image information and one-dimensional spectral information. It can observe both the two-dimensional spatial information and the spectral information of each pixel.

[0003] Spatial information in an image reflects external features such as the size, shape, and defects of the target object, while spectral information reflects the physical and chemical composition of the target object. Therefore, by analyzing and processing spectral information, we can identify the physical and chemical information such as the material, texture, and components of a substance. Furthermore, we can quickly and intuitively identify the relevant location and range through the spatial information of the image.

[0004] In classic HSI systems, since the system is based on a single discrete device, in order to ensure spatial and spectral resolution, optical devices such as objectives, apertures, collimators, and various lenses must be introduced. At the same time, the focusing and collimation problems between various devices must be considered. This results in traditional HSI systems being very complex, large in size, and expensive, which greatly limits their application range.

[0005] Furthermore, in order to filter out the target's characteristic spectral bands and achieve target differentiation, a narrowband filter is integrated onto the spectral imaging chip, which allows for tunable filtering at the center of the desired band (e.g., ...). Figure 7 As shown, the center wavelength of a narrowband filter is tunable within a certain range. However, due to the limitations of existing high and low refractive indices, the spectral bandwidth cannot cover the entire spectrum (e.g., Figure 7 As shown, the cutoff bandwidth is less than 200nm, and there is interference from other band signals, such as... Figure 8 As shown, in addition to the required band, other bands have an impact. An external cutoff filter (such as...) is required. Figure 9 As shown, this is the cutoff interference band. Existing external cutoff filters, which are deposited separately and then bonded to the image sensor, reduce spectral transmittance, leading to decreased quantum efficiency and affecting imaging performance.

[0006] Existing handheld portable spectral imaging devices typically employ a traditional mechanism, separating the spectral dispersion and imaging components. This includes three common approaches: Approach 1: A switchable filter is placed in front of the image sensor. This approach can only image one spectral band at a time. When switching to another spectral band, a mechanical structure moves / rotates the required new filter in front of the imaging component. This design introduces numerous moving mechanisms, severely impacting system integration and stability, reducing system uptime, and increasing maintenance difficulty. Furthermore, the presence of moving mechanisms and filter arrays inevitably increases the overall system size; acquiring multiple spectral band images of the same scene requires constant staring and multiple filter switching, failing to achieve the goal of rapidly acquiring a complete spectral data cube. Approach 2: A liquid crystal tunable filter (LCTF) unit is placed in front of the image sensor. Voltage controls the LCTF to adjust to a specific wavelength, after which the image sensor images, then adjusts to the next wavelength, and so on. The process is similar to Approach 1. Besides the drawbacks of low imaging speed and the need for constant staring, this method also suffers from low light transmittance and uneven transmittance within the field of view. Under normal light sources, it is practically impossible to achieve a clear image of the target. Solution three involves placing a MEMS-FP cavity (Micro-Electro-Mechanical Systems-Fabry-Perot Resonator) filter unit in front of the image sensor. This solution is similar to solution two above, using a MEMS mechanism to control the thickness of the FP cavity to achieve filtering effects across different spectral bands. In addition to the aforementioned drawbacks, existing MEMS-FP cavity filters struggle to achieve a field of view exceeding the millimeter level, and their low transmittance limits their application to single-point detection, making them unsuitable for imaging detection. Summary of the Invention

[0007] The present invention aims to solve at least one of the technical problems existing in the prior art.

[0008] This invention provides a handheld multispectral imager, which includes an image sensor comprising: a pixel photosensitive unit for image acquisition and data readout; a first matching layer integrally deposited on the pixel photosensitive unit for improving the transmittance of the center wavelength of the image sensor; and a beam-splitting structure comprising multiple periodically distributed periods, each period comprising a narrowband filter integrally deposited on the first matching layer for tunability of the center wavelength in a desired band; the narrowband filter comprising multiple FP cavity structures arranged in a mosaic pattern.

[0009] Furthermore, the image sensor also includes a second matching layer, which is integrally deposited and grown on the beam-splitting structure. The second matching layer is used to improve the transmittance of the center wavelength of the image sensor.

[0010] Furthermore, the image sensor also includes: a transition layer integrally deposited and grown on a narrowband filter film; a first cutoff filter film integrally deposited and grown on the transition layer, the first cutoff filter film being used to cut off a first interference band; a second cutoff filter film integrally deposited and grown on the first cutoff filter film, the second cutoff filter film being used to cut off a second interference band, the second interference band being different from the first interference band; and a third cutoff filter film integrally deposited and grown on the second cutoff filter film, the third cutoff filter film being used to cut off a third interference band, the third interference band being different from both the first and second interference bands.

[0011] Furthermore, the image sensor also includes a cutoff filter, which is attached to the narrowband filter film and is used to cut off interference bands.

[0012] Furthermore, each cycle also includes multiple polarization filter structures with different polarization directions, and these multiple polarization filter structures are randomly arranged with multiple FP cavity structures.

[0013] Furthermore, each cycle includes four polarization filter structures with polarization angles of 0°, 45°, 90° and 135° respectively.

[0014] Furthermore, each period also includes at least one fully transparent spectral structure, which is randomly arranged with multiple polarization filter structures and multiple FP cavity structures.

[0015] Furthermore, each cycle also includes at least one bandpass broadband filter structure, which is randomly arranged with multiple polarization filter structures and multiple FP cavity structures.

[0016] Furthermore, multiple polarization filter structures are integrally deposited and grown on the first matching layer.

[0017] Furthermore, the handheld multispectral imager also includes: an imaging lens group, which is used to transmit light within the spectral range of the handheld multispectral imager and focus the transmitted light onto the image sensor; a readout circuit, which is connected to the image sensor; and a control circuit, which includes a processor and a communication module, with the processor connected to the readout circuit and the communication module respectively.

[0018] The present invention provides a handheld multispectral imager, which includes an image sensor. The image sensor is formed by integrally depositing a narrowband filter film on a first matching layer, which is integrally deposited on a pixel photosensitive unit. There are no gaps between the narrowband filter film, the first matching layer and the pixel photosensitive unit, resulting in high spectral transmittance, reduced energy loss, and integral molding in a single fabrication process. It is not affected by external environmental pollution, has better robustness, and has higher fabrication efficiency and integration. In this invention, due to the significant difference in refractive index between the narrowband filter material and the pixel photosensitive unit material of the image sensor during the growth process, direct growth would lead to refractive index mismatch and a decrease in center wavelength transmittance, resulting in low quantum efficiency of the spectral imaging system and affecting imaging performance. Therefore, by setting a matching layer between the pixel photosensitive unit and the narrowband filter, the problems of refractive index mismatch and decreased center wavelength transmittance can be effectively overcome, effectively improving the center wavelength transmittance of the image sensor. While increasing transmittance, the bandwidth is reduced, allowing for the preparation of more spectral bands and the acquisition of more spectral lines within a fixed cutoff range. The overlap between adjacent spectral bands is also reduced, making data processing easier and effectively improving the spectral resolution of the handheld multispectral imager. Attached Figure Description

[0019] The accompanying drawings, which form part of this specification, are provided to further illustrate embodiments of the invention and, together with the textual description, explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0020] Figure 1 A partial structural schematic diagram of an image sensor (only one FP cavity structure of the narrowband filter is shown) provided according to a specific embodiment of the present invention is illustrated.

[0021] Figure 2 A schematic diagram of the beam-splitting structure of an image sensor according to a specific embodiment of the present invention is shown;

[0022] Figure 3 This diagram illustrates the peak transmittance at the center wavelength with and without a matching layer according to a specific embodiment of the present invention.

[0023] Figure 4 A schematic diagram of the center wavelength peak transmittance of the unmatched layer, the substrate-side matching layer, and the air-side matching layer provided according to a specific embodiment of the present invention is shown.

[0024] Figure 5A schematic diagram of the center wavelength peak transmittance of the unmatched layer, the L-matched layer, and the HL-matched layer provided according to a specific embodiment of the present invention is shown.

[0025] Figure 6 A partial structural schematic diagram of an image sensor (only one FP cavity structure of the narrowband filter is shown) provided according to a specific embodiment eleven of the present invention is illustrated.

[0026] Figure 7 A schematic diagram of a narrowband filter in the prior art is shown;

[0027] Figure 8 A schematic diagram of a narrowband filter in the prior art that is subject to interference from signals in other bands is shown;

[0028] Figure 9 A schematic diagram of a cutoff filter membrane in the prior art is shown;

[0029] Figure 10 A schematic diagram of the structure of a polarization-type image sensor in the prior art is shown;

[0030] Figure 11 A schematic diagram of a single-period structure of a beam splitter with a polarization filtering structure provided according to a specific embodiment of the present invention;

[0031] Figure 12 A schematic diagram of the structure of a handheld multispectral imager provided according to a specific embodiment of the present invention is shown.

[0032] The above figures include the following reference numerals:

[0033] 10. Pixel photosensitive unit; 20. Narrowband filter film; 30. First cutoff filter film; 40. Transition layer; 50. First matching layer; 60. Second cutoff filter film; 70. Third cutoff filter film. Detailed Implementation

[0034] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0036] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0037] As a first embodiment of the present invention, such as Figure 1 As shown, a handheld multispectral imager is provided. The handheld multispectral imager includes an image sensor, which includes: a pixel photosensitive unit 10, a first matching layer 50, and a beam-splitting structure. The pixel photosensitive unit 10 is used to realize image acquisition and data readout. The first matching layer 50 is integrally deposited and grown on the pixel photosensitive unit 10, and is used to improve the transmittance of the center wavelength of the image sensor. The beam-splitting structure includes multiple periods distributed in a periodic manner. Each period includes a narrowband filter 20, which is integrally deposited and grown on the first matching layer 50. The narrowband filter 20 is used to realize tunability of the center wavelength in the desired band. The narrowband filter 20 includes multiple FP cavity structures distributed in a mosaic pattern.

[0038] In a first embodiment of the present invention, the handheld multispectral imager includes an image sensor. The image sensor is formed by integrally depositing a first matching layer on the pixel photosensitive unit and integrally depositing a narrowband filter on the first matching layer. There are no gaps between the narrowband filter, the first matching layer, and the pixel photosensitive unit, resulting in high spectral transmittance, reduced energy loss, and a one-time fabrication process that is unaffected by external environmental contamination, offering better robustness, higher fabrication efficiency, and higher integration. In this invention, because the refractive index difference between the narrowband filter material and the pixel photosensitive unit material of the image sensor is significant during the growth process, direct growth would lead to refractive index mismatch and a decrease in center wavelength transmittance, resulting in low quantum efficiency of the spectral imaging system and affecting imaging performance. Therefore, by setting a matching layer between the pixel photosensitive unit and the narrowband filter, the problem of refractive index mismatch and decreased center wavelength transmittance can be effectively overcome, effectively improving the center wavelength transmittance of the image sensor. While increasing transmittance, the bandwidth is reduced, allowing for the fabrication of more spectral bands and the acquisition of more spectral lines within a fixed cutoff range, with less overlap between adjacent spectral bands. Obtaining a smaller bandwidth effectively improves the spectral resolution of the spectroscopic imaging system. The improved spectral resolution expands the system's application scenarios, shifting the focus of spectral imaging material detection from a technology heavily reliant on classification and recognition algorithms to one that precisely measures the absorption and reflectance of substances at specific wavelengths, significantly increasing the system's confidence level. Furthermore, the enhanced resolution of the spectroscopic imaging system alleviates the burden on subsequent data processing. Previously computationally intensive classification and recognition algorithms may become unnecessary, eliminating the need for high-performance processors and reducing system cost, power consumption, development complexity, and reliability.

[0039] like Figure 2 As shown, a specific embodiment is provided, in which the spectral structure has a 4*4 size as one cycle, and each cycle includes 16 FP cavity structures with different spectral bands distributed in a mosaic pattern. By extracting and combining the pixel data of the same position in each cycle, the spectral image of the corresponding spectral band at that position can be obtained.

[0040] As a second embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager, based on the first embodiment, further defines the film structure of the image sensor. In this embodiment, the film structure of the image sensor is configured as Sub|Q1(HL)^S1 H 2nL H(LH)^S2|Air, where Q1 is the film structure of the first matching layer 50, (HL)^S1 H 2nL H(LH)^S2 is the film structure of the narrowband filter 20, n is the film thickness adjustment coefficient of the narrowband filter 20, H is a high refractive index material, L is a low refractive index material, and S1 and S2 are the number of stacking operations. In the second embodiment of the present invention, by configuring the specific model structure of the image sensor, tunable center filtering in the desired band and improved center wavelength transmittance can be achieved.

[0041] As a third embodiment of the present invention, a handheld multispectral imager is provided, which further defines the film structure of the first matching layer based on the first embodiment. In this embodiment, the film structure Q1 of the first matching layer 50 includes L or HL, where H represents a high refractive index material and L represents a low refractive index material.

[0042] Specifically, in this third embodiment, any image sensor can be represented by an equivalent interface, whose reflection, transmission, and phase characteristics are determined by the combined admittance of the incident medium and the equivalent interface. Essentially, the effect of any thin film layer can be viewed as altering the admittance of the equivalent interface, thereby changing the optical properties of the thin film system. Optical admittance is the ratio of electric field strength to magnetic field strength; in the optical band, optical admittance is numerically equal to the refractive index.

[0043] On the substrate (refractive index n) s When the beam has only one thin film (i.e., any H or L, a single-layer thin film), its characteristic matrix is ​​as follows when the beam is incident perpendicularly from air (n0 = 1):

[0044]

[0045] The above formula contains all the useful parameters of the thin film, where, B is the electric field strength, C is the magnetic field strength, δ1 is the phase thickness of the first thin film, n1 is the refractive index of the first thin film, d1 is the film thickness of the first thin film, λ is the center wavelength, θ1 is the incident angle of the first thin film, η1 is the tilt optical admittance of the first thin film, and η s The tilted optical admittance is the base, and i is a complex number.

[0046] Depend on From the expression of the matrix, we can see that when the effective optical thickness of the thin film is an integer multiple of 1 / 4 wavelength, that is...

[0047]

[0048] Where n is the refractive index, d is the film thickness, and θ is the incident angle.

[0049] or its phase thickness is Integer multiples of, i.e.

[0050]

[0051] Where δ is the phase thickness of the film;

[0052] The characteristic matrix of the thin film is

[0053]

[0054]

[0055] R = [(η0 - η] S ) / (η0+η S )] 2

[0056] Where Y represents optical admittance, R is reflectivity, η0 is optical admittance at the center wavelength λ, and the characteristic matrix of the thin film is an identity matrix. At the reference wavelength λ, it has no effect on the reflection or transmission characteristics of the film system. This thin film is called a dummy layer.

[0057] Taking a currently designed image sensor as an example, the narrowband filter film is essentially a dummy layer, which does not affect the spectral transmittance. The film structure is as follows:

[0058] Sub|(HL)^3H 2nL H(LH)^3|Air

[0059] At the center wavelength λ, the middle cavity layer is an even multiple of λ / 4 and has no effect on the transmittance of the center wavelength, so it can be removed. In the remaining structure, two adjacent high refractive index film layers form a λ / 2 layer, which can also be removed. In this way, all film layers are removed, and finally, the Sub|Air structure is obtained.

[0060] Due to the difference between the refractive index of the substrate and the refractive index of air, residual reflectivity inevitably exists at the center wavelength. This can be addressed by adding a matching layer to improve transmittance at the center wavelength. For example... Figure 3 As shown, the peak transmittance at the center wavelength with a matching layer is significantly higher than that without a matching layer. Introducing the concept of a dummy layer transforms the design problem of the matching layer into an antireflection coating design primarily related to the substrate. For Sub|Air, a thick, low-refractive-index layer can be added near the substrate or on the air side to act as a matching layer.

[0061] For the case of a low-refractive-index spacer layer (i.e., 2L), the half-width is expressed by the following formula:

[0062]

[0063] Where x represents the total number of high-refractive-index layers in the multilayer reflective film. Without a matching layer, the multilayer reflective film refers to the upper Bragg mirror; with a matching layer, it refers to the multilayer film before the 2L spacer layer, including the high-refractive-index layers within the spacer layer. When the film system structure is Sub|(HL)^3H 2LH(LH)^3|Air, X = 4; when the film system structure is Sub|HL(HL)^3H 2L H(LH)^3LHL|Air, X = 5. m represents the interference order, and n... H n is the refractive index of a high-refractive-index material. L The refractive index is the refractive index of the low-refractive-index material.

[0064] According to equation (1), the half-width of the membrane system before adding the matching layer is:

[0065]

[0066] The half-width after adding a low-refractive-index matching layer to the substrate side is:

[0067]

[0068] Based on the half-width at half-maximum (WWHM) after adding a matching layer to the substrate side, it can be seen that the addition of the matching layer improves the transmittance of the filter while changing the WWHM, and the change in WWHM affects the resolution. Adding a matching layer on the side closer to the substrate can reduce the WWHM while improving the transmittance of the filter. A reduced WWHM allows for the preparation of more spectral bands within a limited cutoff range, reduces the overlap between adjacent spectral bands, and better identifies the characteristics of different spectral bands. However, a too narrow WWHM is not conducive to signal recognition. Therefore, the WWHM can be adjusted according to the actual number of spectral bands and the required signal recognition rate.

[0069] As a fourth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager introduces a second matching layer based on the image sensor provided in the first embodiment. The second matching layer is integrally deposited and grown on the narrowband filter 20. The second matching layer is used to improve the peak transmittance of the center wavelength of the image sensor. In this fourth embodiment, a first matching layer is disposed on the substrate side and a second matching layer is disposed on the air side. The addition of the first and second matching layers improves the transmittance of the filter while changing the half-width. Figure 4As shown, adding a matching layer to the substrate side reduces the half-width at half-maximum (WWHM), while adding it to the air side increases it. To make the bandwidth with and without a matching layer close to that without a matching layer, matching layers can be added simultaneously to both the substrate and air sides, thus ensuring that the WWHM remains unchanged.

[0070] As a fifth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager is based on the fourth embodiment, and the film structure of the image sensor is further defined. In this embodiment, the film structure is Sub|Q1(HL)^S1 H 2nL H(LH)^S2 Q2|Air, where Q1 is the film structure of the first matching layer 50, (HL)^S1 H 2nL H(LH)^S2 is the film structure of the narrowband filter 20, n is the film thickness adjustment coefficient of the narrowband filter 20, Q2 is the film structure of the second matching layer, H is a high refractive index material, L is a low refractive index material, and S1 and S2 are the number of stacking times.

[0071] As a sixth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager is based on the fifth embodiment, with specific definitions for the first and second matching layers. In this embodiment, the film structure is Sub|HL(HL)^3H 2nL H(LH)^3LHL|Air, and its half-width is... To obtain, where λ is the center wavelength, m represents the interference order, and n H n is the refractive index of a high-refractive-index material. L η is the refractive index of a low-refractive-index material. s The tilted optical admittance of the substrate. As a specific embodiment of the invention, the half-width of the image sensor is...

[0072] As a seventh embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager further defines the film structure of the image sensor based on the first embodiment. In this embodiment, the film structure with a low refractive index layer added to the substrate side is Sub|L(HL)^3H 2nL H(LH)^3|Air. The film structure with a high refractive index layer and a low refractive index layer added to the substrate side is Sub|HL(HL)^3H 2nL H(LH)^3|Air. The transmittance curve is shown below. Figure 5 As shown, after adding the matching layer L, the transmittance of the center wavelength is 92.78%; after adding the matching layer HL, the transmittance of the center wavelength is 94.68%, which is even higher.

[0073] As an eighth embodiment of the present invention, a handheld multispectral imager is provided. The handheld multispectral imager includes a pixel photosensitive unit 10, a beam splitting structure, and a third matching layer. The pixel photosensitive unit 10 is used to realize image acquisition and data readout. A narrowband filter 20 of the beam splitting structure is integrally deposited and grown on the pixel photosensitive unit 10. The narrowband filter 20 is used to realize tunability at the center wavelength of the desired band. The third matching layer is integrally deposited and grown on the narrowband filter 20. The third matching layer is used to improve the peak transmittance of the center wavelength of the image sensor.

[0074] In the eighth embodiment of the present invention, considering that the refractive index difference between the film material and the pixel photosensitive unit material of the image sensor is large during the growth process of the narrowband filter film, direct growth will lead to refractive index mismatch and a decrease in the center wavelength peak transmittance, which will result in low quantum efficiency of the spectral imaging system and affect the imaging effect. Therefore, by integrally growing a third matching layer on the upper layer of the narrowband filter film, the problem of refractive index mismatch and decrease in center wavelength peak transmittance can be effectively overcome, and the center wavelength peak transmittance of the image sensor can be effectively improved.

[0075] As a ninth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager further defines the film structure of the image sensor based on the eighth embodiment. In this embodiment, the film structure of the image sensor is Sub|(HL)^S1 H 2nL H(LH)^S2Q3|Air, where (HL)^S1 H 2nLH(LH)^S2 is the film structure of the narrowband filter 20, n is the film thickness adjustment coefficient of the narrowband filter 20, Q3 is the film structure of the third matching layer, H is a high refractive index material, L is a low refractive index material, and S1 and S2 are the number of stacking operations.

[0076] Specifically, in this invention, the film structure selection of the matching layer of the image sensor is shown in Table 1. Q1 and Q2 have a corresponding relationship: when Q1 is L, there is no Q2; when Q2 is L, there is no Q1; when Q1 is HL, there is no Q2 or Q2 is LHL; when Q1 is LHL, Q2 is LH.

[0077] Table 1 Selection of Matching Layer Membrane System Structure

[0078] Q1 Q2 Equivalent to L <![CDATA[ Sub|L|Air (basal side) L <![CDATA[ Sub|L|Air (Air side) HL <![CDATA[ Sub|HL|Air (basal side) HL LHL <![CDATA[ Sub|L|Ar (Air side) LHL LH <![CDATA[ Sub|L|Air (basal side)

[0079] As a tenth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager, based on the eighth embodiment, specifies how the half-width of the image sensor is determined. In this embodiment, the half-width of the image sensor can be determined according to... To obtain, where λ is the center wavelength, x represents the total number of high refractive index layers in the multilayer reflective film, m represents the interference order, and nH n is the refractive index of a high-refractive-index material. L The refractive index is the refractive index of the low-refractive-index material.

[0080] As the eleventh embodiment of the present invention, such as Figure 6 As shown, a handheld multispectral imager is provided, which further defines the image sensor based on the first embodiment. In this embodiment, the image sensor further includes a transition layer 40, which is integrally deposited and grown on the narrowband filter film 20; a first cutoff filter film 30, which is integrally deposited and grown on the transition layer 40, and is used to cut off a first interference band; a second cutoff filter film 60, which is integrally deposited and grown on the first cutoff filter film 30, and is used to cut off a second interference band, which is different from the first interference band; and a third cutoff filter film 70, which is integrally deposited and grown on the second cutoff filter film 60, and is used to cut off a third interference band, which is different from both the first and second interference bands.

[0081] In the eleventh embodiment of the present invention, the image sensor integrally deposits and grows a transition layer on a narrowband filter film, and integrally deposits and grows a first cutoff filter film on the transition layer. There are no gaps between the first cutoff filter film, the transition layer, the narrowband filter film, and the pixel photosensitive unit, resulting in high spectral transmittance, reduced energy loss, and a one-time fabrication process that is integrally formed, unaffected by external environmental contamination, and exhibits better robustness, higher fabrication efficiency, and higher integration. By integrally depositing and growing a second cutoff filter film on the first cutoff filter film and an integrally depositing and growing a third cutoff filter film on the second cutoff filter film, the cutoff range of the interference band can be effectively broadened. Furthermore, since the equivalent refractive indices of the narrowband filter film and the first cutoff filter film are different, direct superposition would affect the peak transmittance. By setting a transition layer between the narrowband filter film and the first cutoff filter film, the peak transmittance of the image sensor can be effectively improved. Compared with the externally bonded cutoff filter film in the prior art, the image sensor provided by this invention integrates the first cutoff filter film and the narrowband filter film into the image sensor, which greatly improves quantum efficiency and spectral transmittance. The second cutoff filter film is placed on the first cutoff filter film, and the third cutoff filter film is placed on the second cutoff filter film, which can broaden the cutoff range of the interference band. The transition layer is set between the narrowband filter film and the first cutoff filter film, which effectively improves the peak transmittance of the image sensor and can effectively improve the spectral resolution of the handheld multispectral imager.

[0082] As a twelfth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager, based on the tenth embodiment, further defines the film structure of the image sensor. In this embodiment, the film structure of the image sensor is configured as Sub|HL H(LH)^S12nL(HL)^S1 H Ln1(W1)^S2n2(W2)^S3n3(W3)^S4|Air, where HL is the film structure of the matching layer 50, and H(LH)^S12nL(HL)^S1 H represents the film structure of the narrowband filter 20, L represents the film structure of the transition layer 40, n1(W1)^S2 represents the film structure of the first cutoff filter 30, n2(W2)^S3 represents the film structure of the second cutoff filter 60, and n3(W3)^S4 represents the film structure of the third cutoff filter 70. W1, W2, and W3 all include high-refractive-index materials and low-refractive-index materials. H represents a high-refractive-index material, L represents a low-refractive-index material, S1, S2, S3, and S4 represent the number of stacking operations, n represents the film thickness adjustment coefficient of the narrowband filter 20, n1 represents the film thickness adjustment coefficient of the first cutoff filter 30, n2 represents the film thickness adjustment coefficient of the second cutoff filter 60, and n3 represents the film thickness adjustment coefficient of the third cutoff filter 70. In this embodiment, by configuring the specific model structure of the image sensor, tunable filtering at the center of the desired wavelength band and prevention of stray light interference can be achieved. In this invention, the film thickness adjustment coefficients n1, n2, and n3 of the cutoff filter film are determined using two methods. The first method involves obtaining them through software simulation. This method uses software to simulate various filter curves and determines the optimal film thickness adjustment coefficients by analyzing the performance differences of the tuned filter curves obtained with different parameters. The second method involves determining the spectral band to be cut off by the cutoff filter film; calculating the center wavelength of the spectral band to be cut off based on the first and second boundary thresholds; and determining the film thickness adjustment coefficients of the cutoff filter film based on the center wavelength of the spectral band to be cut off and the center wavelength of the narrowband filter film. This method uses numerical calculation to obtain the film thickness adjustment coefficients, which is simple and can achieve effective cutoff in a specific band. In practical applications, the appropriate coefficient can be selected according to actual needs.

[0083] As a thirteenth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager, based on the above embodiments, further defines the parameters of the film structure of the image sensor. In this embodiment, S1 = 5-7, S2, S3, S4 = 8-13, n1, n2, n3 = 0.5-2.5. Wherein Sub is the substrate Si, Air is air, H represents high-refractive-index materials Ta2O5, Ti3O5, TiO2, Si3N4, and Nb2O5; L represents one or a mixture of low-refractive-index materials SiO2, MgF2, and Al2O3.

[0084] As a fourteenth embodiment of the present invention, a handheld multispectral imager is provided, which further defines the cutoff filter film based on the above embodiments. In this embodiment, the first cutoff filter film is integrally deposited and grown on the narrowband filter film using semiconductor technology. The first cutoff filter film uses a material compatible with semiconductor technology, thereby further improving spectral transmittance and reducing energy loss. W1, W2, and W3 all include (0.5LH0.5L) or (0.5HL0.5H). The first cutoff filter film 30, the second cutoff filter film 60, and the third cutoff filter film 70 are all prepared by alternating deposition of high-refractive-index materials and low-refractive-index materials. The high-refractive-index materials of the first cutoff filter film 30, the second cutoff filter film 60, and the third cutoff filter film 70 all include Ta2O5, Ti3O5, TiO2, Si3N4, or Nb2O5, and the low-refractive-index materials of the first cutoff filter film 30, the second cutoff filter film 60, and the third cutoff filter film 70 all include at least one of SiO2, MgF2, and Al2O3. By limiting the cutoff filter film, quantum efficiency and spectral transmittance can be greatly improved.

[0085] As the fifteenth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager further defines the structure of the narrowband filter film based on the above embodiments. By setting the structure of the narrowband filter film, the structural complexity of the chip structure can be effectively reduced, the structural volume can be reduced, and the cost can be reduced. In this embodiment, the pixel photosensitive unit includes multiple pixel photosensitive areas, and multiple FP cavity structures are arranged one-to-one with the multiple pixel photosensitive areas. The multiple FP cavity structures are all formed in one step using semiconductor technology. Each FP cavity structure includes a first reflector, a light-transmitting layer, and a second reflector stacked sequentially from bottom to top. The first reflector, the light-transmitting layer, the second reflector, and the pixel photosensitive areas are all made of semiconductor-compatible materials and are strictly aligned vertically without any post-lamination parts. This method utilizes advanced semiconductor (CMOS) process technology to directly fabricate the traditional spectral splitting system onto the pixel photosensitive unit of the photoelectric sensor. Due to the close connection, stray light is reduced, and photon utilization is improved, thus achieving a speed of hundreds of frames per second and realizing spectral video functionality. Its size and weight are no different from ordinary RGB chips, enabling an imaging system the size of a finger. CMOS technology brings unparalleled integration to image sensors, allowing for highly integrated connections with any circuit, such as embedding in mobile phones.

[0086] As the sixteenth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager further defines the first and second reflecting mirrors based on the fifteenth embodiment. In this embodiment, the first reflecting mirror is a lower reflecting mirror, and the second reflecting mirror is an upper reflecting mirror. The upper reflecting mirror is fabricated by alternating layers of high-reflectivity materials and multiple layers of low-reflectivity materials to form a Bragg reflector, which overlaps multiple times, achieving a reflectivity of over 99%, serving as the cavity mirror of the FP cavity structure. The lower reflecting mirror has the same structure and materials as the upper reflecting mirror and is located between the light-transmitting layer and the pixel photosensitive area, also exhibiting high reflectivity.

[0087] As the seventeenth embodiment of the present invention, a handheld multispectral imager is provided, which further defines the film thickness adjustment coefficient of the cutoff filter film based on the above embodiments. This embodiment describes in detail a second method for obtaining the film thickness adjustment coefficient of the cutoff filter film. In this embodiment, the film thickness adjustment coefficient can be obtained according to the following steps: determining the spectral band to be cut off by the cutoff filter film; calculating the center wavelength of the spectral band to be cut off based on a first boundary threshold and a second boundary threshold; and determining the film thickness adjustment coefficient of the cutoff filter film based on the center wavelength of the spectral band to be cut off and the center wavelength of the narrowband filter film.

[0088] In the seventeenth embodiment of the present invention, by optimizing the design of the cutoff filter film, that is, by designing the film thickness adjustment coefficient of the cutoff filter film, specifically by calculating the center wavelength of the spectral band to be cut off based on the first boundary threshold and the second boundary threshold, the film thickness adjustment coefficient of the cutoff filter film is determined by the center wavelength of the spectral band to be cut off and the center wavelength of the narrowband filter film. In this way, when the cutoff filter film with the film thickness adjustment coefficient is integrally deposited on the narrowband filter film, the leakage light outside the free spectrum range can be greatly suppressed, the interference band can be cut off, the side mode suppression ratio of the spectral filter can be greatly improved, and the spectral imaging performance of the image sensor can be improved.

[0089] As the eighteenth embodiment of the present invention, an image sensor is provided, which, based on the above embodiments, defines the center wavelength of the cutoff spectral band. In this embodiment, the center wavelength of the cutoff spectral band can be determined according to... To obtain; or, the center wavelength of the spectral band to be cut off can be obtained according to The above describes two methods for obtaining the center wavelength of the spectral band to be cut off, where λ0 is the center wavelength of the spectral band to be cut off, λ1 is the first boundary threshold of the spectral band to be cut off, and λ2 is the second boundary threshold of the spectral band to be cut off. This method obtains the center wavelength of the spectral band to be cut off, resulting in higher calculation accuracy and better assurance of suppressing light leakage outside the free spectral range (compared to the formula). (Obtain the center wavelength of the spectral band to be cut off).

[0090] As the nineteenth embodiment of the present invention, an image sensor is provided, which, based on the above embodiments, limits the film thickness adjustment coefficient of the cutoff filter film. In this embodiment, the film thickness adjustment coefficient n of the cutoff filter film can be determined according to... The wavelength λ is obtained by using the method described above, where λ is the center wavelength of the narrowband filter, and n = n1, n2, or n3. This method of determining the film thickness adjustment coefficient of the cutoff filter film can significantly suppress light leakage outside the free spectral range, effectively cut off interference bands, greatly improve the side-mode suppression ratio of spectral filtering, and enhance the spectral imaging performance of the image sensor.

[0091] As a twentieth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager further defines the image sensor based on the first embodiment. In this embodiment, the image sensor also includes a cutoff filter, which is adhered to the narrowband filter 20. The cutoff filter is used to block interference bands. This embodiment, by designing the image sensor to include a cutoff filter, which is adhered to the narrowband filter, ensures that the chip structure can block interference bands and greatly simplifies the manufacturing process.

[0092] In practical applications, especially in complex environments such as outdoor day-night cycles and foggy weather, the accuracy of information acquired by single-chip micro-spectral imaging systems decreases, making accurate target identification difficult. Polarized light has a long history in machine vision inspection, for example, in detecting stress points, identifying targets, and reducing glare from transparent objects. A typical polarization system requires one or more additional polarizers placed between the target and the camera to detect material stress, enhance contrast, and analyze surface indentations or scratches. Polarization imaging technology is a widely used detection technique for outdoor target detection and industrial quality monitoring, identifying targets based on differences in their polarization characteristics. However, due to the limited types of targets identifiable by polarization characteristics, it is difficult to accurately identify multiple targets in complex environmental backgrounds using only polarization information. Combining spectral imaging and polarization detection technologies, simultaneously acquiring the spectral, spatial, and polarization information of targets, enables real-time and effective monitoring and identification of multiple types of targets in complex background environments. To achieve simultaneous acquisition of polarization, spectral, and imaging information, existing technologies employ a pixel-level integrated photonic crystal spectral modulation structure superimposed with a four-angle polarization photonic lattice structure (0°, 45°, 90°, 135°) along the vertical detector beam-splitting layer. Figure 10As shown, this method can simultaneously acquire target polarization and spectral imaging information. While using the spectrum for material identification, it also enhances contrast through polarization, which can overcome the influence of complex background environments on the identification results to some extent. The integrated photonic crystal structure in this technical solution achieves polarization and spectral filtering effects by changing the lattice constant and lattice direction. This structure is complex and requires advanced manufacturing processes. Each pixel contains both spectral and polarization information, increasing the difficulty of algorithm analysis.

[0093] As the twenty-first embodiment of the present invention, a handheld multispectral imager is provided. Based on the first embodiment, the handheld multispectral imager further defines the beam-splitting structure. In this embodiment, each cycle of the beam-splitting structure also includes multiple polarization filter structures with different polarization directions, and the multiple polarization filter structures and multiple FP cavity structures are randomly arranged.

[0094] In the twenty-first embodiment of the present invention, by fabricating the FP cavity structure of the narrowband filter film and the polarization filter structure in the same layer of the beam-splitting structure, the advantages of polarization enhancement and spectral recognition can be combined to improve the accuracy of target recognition in complex background environments, reduce dependence on external light sources and internal subsequent gain, and provide more complete restoration of information in each spectral band, effectively improving the spectral resolution of handheld multispectral imagers. At the same time, this structure is simple, the fabrication process is mature, and the algorithms for analyzing spectral and polarization information are simple, allowing for application in harsh and demanding environments, such as at night, under glare, or in foggy conditions. This significantly expands its application scenarios in fields such as security monitoring, military anti-camouflage applications, outdoor environmental monitoring, and smart agriculture.

[0095] As the twenty-second embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager is based on the twenty-first embodiment, but further defines multiple polarization filter structures. In this embodiment, each cycle includes four polarization filter structures, and the polarization angles of the four polarization filter structures are 0°, 45°, 90° and 135°, respectively.

[0096] In the twenty-second embodiment of the present invention, the polarization filter structure adopts a four-quadrant grating structure with polarization angles of 0°, 45°, 90°, and 135°. The complete polarization information of the target can be formed by combining the polarization information from these four directions. The four-quadrant grating structure is simple, can be fabricated using thin films, has a mature fabrication process, and can comprehensively acquire target polarization information. Furthermore, based on the twenty-second embodiment of the present invention, other types of polarization filter structures can be derived and modified based on four-quadrant polarization.

[0097] As the twenty-third embodiment of the present invention, such as Figure 11As shown, a handheld multispectral imager is provided. Based on the twenty-second embodiment, this handheld multispectral imager further defines multiple polarization filter structures. In this embodiment, the beam-splitting structure has a 3x3 period. Within each period, five FP cavity structures with five spectral bands and four polarization filter structures with different polarization directions are alternately arranged. The five FP cavity structures represent five different spectral bands, forming four-neighbor pixel spectral and polarization information. The alternating arrangement of polarization filter structures and FP cavity structures results in uniform target spectral and polarization information, which is beneficial for recovering the true image and facilitating analytical calculations. Based on the four-neighbor pixel spectral and polarization information, the polarization and spectral information of this period can be reconstructed to obtain the polarization and spectral information of the entire image captured by the detector. Based on the spectral information within a single period, the spectral curve of the target image in that period can be obtained. Based on the four-quadrant grating structure, the polarization information of the incident light in four directions within that period can be obtained. According to Stokes' theorem, the light polarization direction of the target within that period can be calculated, thus obtaining a full-frame polarized image.

[0098] The aforementioned technical solution involves a beam splitting structure incorporating polarization filtering. When applied to image sensors, this structure allows for interpolation of polarization and spectral information within a specific spectral band using spectral and polarization information from adjacent pixels. This enables simultaneous acquisition of polarization information from a two-dimensional image. By fusing spectral and polarization information, target classification and recognition are performed, significantly improving the accuracy of target identification in challenging environmental conditions.

[0099] As the twenty-fourth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager is based on the twenty-first embodiment, but further defines the beam-splitting structure. In this embodiment, each period of the beam-splitting structure further includes at least one fully transparent spectral band structure, and the at least one fully transparent spectral band structure is randomly arranged with multiple polarization filter structures and multiple FP cavity structures.

[0100] In the twenty-fourth embodiment of the present invention, each period of the beam-splitting structure further includes at least one fully transparent spectral band structure. The fully transparent spectral band has no beam-splitting effect on the incident light, but can acquire full-spectrum information for signal compensation of the spectral filtering structure. In particular, when the beam-splitting structure is a FP cavity structure, the light signal acquired by the image sensor is weak. By adding a fully transparent spectral band structure to the beam-splitting structure, the signal-to-noise ratio of the image sensor can be improved, which can effectively improve the spectral resolution of the handheld multispectral imager.

[0101] As the twenty-fifth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager, based on the above embodiments, further defines the beam-splitting structure. In this embodiment, each cycle of the beam-splitting structure further includes at least one bandpass broadband filter structure, and the at least one bandpass broadband filter structure is randomly arranged with multiple polarization filter structures and multiple FP cavity structures. In this embodiment, by rationally designing the broadband filtering range, specific spectral bands can be transmitted, thereby meeting the needs of different application scenarios.

[0102] As a twenty-sixth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager, based on the above embodiments, further defines the growth method of multiple polarization filter structures. In this embodiment, multiple polarization filter structures are integrally deposited and grown on a first matching layer 50. By integrally depositing and growing multiple polarization filter structures on the first matching layer 50, the volume of the beam-splitting layer can be reduced, energy loss can be reduced, and robustness, fabrication efficiency, and integration can be improved, effectively enhancing the spectral resolution of the handheld multispectral imager.

[0103] As the twenty-seventh embodiment of the present invention, such as Figure 12 As shown, a handheld multispectral imager is provided. This handheld multispectral imager is based on the above embodiments and further defines the handheld multispectral imager. In this embodiment, the handheld multispectral imager also includes an imaging lens group, a readout circuit, and a control circuit. The imaging lens group is used to transmit light within the spectral range index of the handheld multispectral imager and focus the transmitted light onto the image sensor. The readout circuit is connected to the image sensor. The control circuit includes a processor and a communication module, and the processor is connected to the readout circuit and the communication module respectively.

[0104] In the twenty-seventh embodiment of the present invention, the handheld multispectral imager acquires a spectral image by using an imaging lens group to transmit light within the spectral range of the handheld multispectral imager and focus it onto an image sensor, using a readout circuit to read the pixel data of the image sensor, using a processor in a control circuit to perform image processing, and transmitting the final image processing result to the outside world through a communication module. The handheld multispectral imager proposed in this embodiment has all the beneficial effects of the handheld multispectral imager in the embodiments described above. There are no gaps between the narrowband filter film, the first matching layer, and the pixel photosensitive unit, resulting in high spectral transmittance and reduced energy loss. It is integrally formed in a one-time manufacturing process, is not affected by external environmental pollution, has better robustness, higher manufacturing efficiency and integration, and greatly improves quantum efficiency and spectral transmittance, effectively improving the spectral resolution of the handheld multispectral imager.

[0105] As the twenty-eighth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager is based on the twenty-seventh embodiment and further defines the handheld multispectral imager. In this embodiment, the control circuit further includes a power supply module, which is connected to the image sensor, the processor and the communication module respectively to provide power support for the handheld multispectral imager.

[0106] As the twenty-ninth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager is further defined based on the twenty-seventh embodiment. In this embodiment, the communication module can be configured as a wireless communication module, which interacts with external devices. For example, the communication module can generate a Wi-Fi hotspot to connect with a compatible smartphone to transmit image signals and control information. In this specific embodiment, the human-computer interaction is implemented by the smartphone through a dedicated APP. The dedicated APP running on the compatible smartphone has the following functions: connecting to the handheld multispectral imager for data interaction via the phone's Wi-Fi function; having a graphical human-computer interaction interface that can display the spectral images acquired by the handheld multispectral imager in real time; having an image acquisition control that can save the current frame image to the phone's storage space after clicking the image acquisition control; having a function to view specific spectral bands that can display only the image of the selected spectral band after clicking to view specific spectral bands; and having a function to view the spectral reflectance curve of a specific location that can display the spectral reflectance curve of the current location after clicking to view the spectral reflectance curve of the specific location.

[0107] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0108] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0109] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A handheld multispectral imager, characterized in that, The handheld multispectral imager includes an image sensor, which comprises: A pixel photosensitive unit (10) is used to realize image acquisition and data readout; A first matching layer (50) is integrally deposited and grown on the pixel photosensitive unit (10). The first matching layer (50) is used to improve the center wavelength transmittance of the image sensor. The beam-splitting structure includes multiple periods arranged in a periodic pattern. Each period includes a narrowband filter (20) integrally deposited on the first matching layer (50). The narrowband filter (20) is used to achieve tunability at the center wavelength of the desired band. The narrowband filter (20) includes multiple FP cavity structures arranged in a mosaic pattern. Each period also includes multiple polarization filter structures with different polarization directions. The multiple polarization filter structures and the multiple FP cavity structures are randomly arranged. The multiple polarization filter structures are integrally deposited on the first matching layer (50). Each period also includes at least one full-transparency spectral structure. The at least one full-transparency spectral structure is randomly arranged with the multiple polarization filter structures and the multiple FP cavity structures. Each period also includes at least one bandpass broadband filter structure. The at least one bandpass broadband filter structure is randomly arranged with the multiple polarization filter structures and the multiple FP cavity structures. The second matching layer is integrally deposited and grown on the beam-splitting structure, and the second matching layer is used to improve the center wavelength transmittance of the image sensor. A transition layer (40) is integrally deposited and grown on the narrowband filter film (20); a first cutoff filter film (30) is integrally deposited and grown on the transition layer (40), and the first cutoff filter film (30) is used to cut off the first interference band. The second cutoff filter film (60) is integrally deposited and grown on the first cutoff filter film (30). The second cutoff filter film (60) is used to cut off the second interference band, which is different from the first interference band. The third cutoff filter film (70) is integrally deposited and grown on the second cutoff filter film (60). The third cutoff filter film (70) is used to cut off the third interference band, which is different from the first interference band and the second interference band. The film thickness adjustment coefficients of the first cutoff filter membrane (30), the second cutoff filter membrane (60), and the third cutoff filter membrane (70) are based on... To obtain, among which, The center wavelength of the narrowband filter. The center wavelength of the spectral band to be cut off.

2. The handheld multispectral imager according to claim 1, characterized in that, The image sensor also includes a cutoff filter, which is attached to the narrowband filter film (20) and is used to cut off interference bands.

3. The handheld multispectral imager according to claim 1, characterized in that, Each cycle includes four polarization filter structures, with polarization angles of 0°, 45°, 90° and 135° respectively.

4. The handheld multispectral imager according to claim 1, characterized in that, The handheld multispectral imager also includes: Imaging lens assembly: The imaging lens assembly is used to focus the light transmitted within the spectral range of the handheld multispectral imager onto the image sensor. A readout circuit is connected to the image sensor; a control circuit includes a processor and a communication module, the processor being connected to the readout circuit and the communication module respectively.

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