Handheld multispectral imager

Abstract

The application provides a handheld multispectral imager, which comprises an image sensor, the image sensor comprising a pixel photosensitive unit, a light splitting structure, a transition layer, a first, a second and a third cut-off filter film, the narrow-band filter film in the light splitting structure being integrally deposited and grown on the pixel photosensitive unit, the transition layer being integrally deposited and grown on the narrow-band filter film, the first cut-off filter film being integrally deposited and grown on the narrow-band filter film, the transition layer being used for transitioning the two film systems of the narrow-band filter film and the first cut-off filter film, the second cut-off filter film being arranged on the first cut-off filter film, and the third cut-off filter film being arranged on the second cut-off filter film, the first, the second and the third cut-off filter films being respectively used for cutting off first, second and third interference wave bands. The technical scheme of the application is used to solve the technical problems of low spectral transmittance and low quantum efficiency caused by the cut-off filter film pasting mode 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 feature spectral bands and achieve target differentiation, a narrowband filter film can be integrated onto the image sensor, enabling tunable filtering at the center of the desired spectral band (e.g., ...). Figure 6 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 6 As shown, the cutoff bandwidth is less than 200nm, and there is interference from other band signals, such as... Figure 7 As shown, in addition to the required band, other bands have an impact. An external cutoff filter (such as...) is required. Figure 8 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 beam-splitting structure comprising multiple periodically distributed cycles, each cycle including a narrowband filter integrally deposited and grown on the pixel photosensitive unit, the narrowband filter being used to achieve tunability at the center wavelength of a desired band; the narrowband filter including multiple FP cavity structures arranged in a mosaic pattern; a transition layer integrally deposited and grown on the beam-splitting structure; and a first cutoff. The filter film consists of a first cutoff filter film integrally deposited and grown on a transition layer, which is used to cut off the first interference band; the transition layer is used to transition between the narrowband filter film and the first cutoff filter film system; a second cutoff filter film is disposed on the first cutoff filter film, which is used to cut off the second interference band, which is different from the first interference band; and a third cutoff filter film is disposed on the second cutoff filter film, which is used to cut off the third interference band, which is different from both the first and second interference bands.

[0009] Furthermore, the film structure of the image sensor is Sub|H(LH)^S12nL(HL)^S1 H Ln1(W1)^S2n2(W2)^S3n3(W3)^S4|Air,H(LH)^S12nL(HL)^S1 H represents the film structure of the narrowband filter, L represents the film structure of the transition layer, W1, W2, and W3 all include high-refractive-index materials and low-refractive-index materials, n1(W1)^S2 represents the film structure of the first cutoff filter, n2(W2)^S3 represents the film structure of the second cutoff filter, and n3(W3)^S4 represents the film structure of the third cutoff filter. H represents the high-refractive-index material, L represents the 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, n1 represents the film thickness adjustment coefficient of the first cutoff filter, n2 represents the film thickness adjustment coefficient of the second cutoff filter, and n3 represents the film thickness adjustment coefficient of the third cutoff filter.

[0010] Furthermore, in the membrane structure of the first cutoff filter membrane, W1 includes (0.5LH0.5L) or (0.5HL0.5H); in the second cutoff filter membrane, W2 includes (0.5LH0.5L) or (0.5HL0.5H); and in the third cutoff filter membrane, W3 includes (0.5LH0.5L) or (0.5HL0.5H).

[0011] Furthermore, the first cutoff filter film, the second cutoff filter film, and the third cutoff filter film 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, the second cutoff filter film, and the third cutoff filter film all include Ta2O5, Ti3O5, TiO2, Si3N4, or Nb2O5, and the low refractive index materials of the first cutoff filter film, the second cutoff filter film, and the third cutoff filter film all include at least one of SiO2, MgF2, and Al2O3.

[0012] Furthermore, the second cutoff filter membrane is adhered to the first cutoff filter membrane.

[0013] Furthermore, the second cutoff filter membrane is integrally deposited and grown on the first cutoff filter membrane.

[0014] Furthermore, the third cutoff filter membrane is attached to the second cutoff filter membrane.

[0015] Furthermore, the third cutoff filter membrane is integrally deposited and grown on the second cutoff filter membrane.

[0016] 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.

[0017] Furthermore, each cycle includes four polarization filter structures with polarization angles of 0°, 45°, 90° and 135°, respectively.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] The present invention provides a handheld multispectral imager, which includes an image sensor. This image sensor is constructed by integrally depositing a narrowband filter film onto a pixel photosensitive unit, an integrally depositing a transition layer onto the narrowband filter film, and an integrally depositing a first cutoff filter film onto 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 prevents external environmental contamination, providing better robustness, higher fabrication efficiency, and higher integration. By placing a second cutoff filter film on the first cutoff filter film and a third cutoff filter film on the second cutoff filter film, the cutoff range of the interference band can be effectively widened. Furthermore, since the narrowband filter film and the first cutoff filter film have different equivalent refractive indices, direct superposition would affect the peak transmittance. By placing 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 in the handheld multispectral imager 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 placement of the second cutoff filter film on the first cutoff filter film and the placement of the third cutoff filter film on the second cutoff filter film can broaden the cutoff range of the interference band. The provision of a transition layer between the narrowband filter film and the first cutoff filter film effectively improves the peak transmittance of the image sensor, thereby significantly enhancing the spectral resolution of the handheld multispectral imager. Attached Figure Description

[0022] 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.

[0023] 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.

[0024] 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;

[0025] Figure 3 A schematic diagram of a single-cycle structure of a beam splitter with a polarization filtering structure provided according to a specific embodiment of the present invention is shown.

[0026] Figure 4A schematic diagram of the structure of a handheld multispectral imager according to a specific embodiment of the present invention is shown;

[0027] Figure 5 A schematic diagram of the structure of a polarization-type image sensor in the prior art is shown;

[0028] Figure 6 A schematic diagram of a narrowband filter in the prior art is shown;

[0029] Figure 7 A schematic diagram of a narrowband filter in the prior art that is subject to interference from signals in other bands is shown;

[0030] Figure 8 A schematic diagram of a cutoff filter membrane in the prior art is shown.

[0031] The above figures include the following reference numerals:

[0032] 10. Pixel photosensitive unit; 20. Narrowband filter film; 30. First cutoff filter film; 40. Transition layer; 60. Second cutoff filter film; 70. Third cutoff filter film. Detailed Implementation

[0033] 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.

[0034] 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.

[0035] 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.

[0036] like Figure 1 As shown, as a first specific embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager includes an image sensor comprising: a pixel photosensitive unit 10, a beam-splitting structure, a transition layer 40, a first cutoff filter film 30, a second cutoff filter film 60, and a third cutoff filter film 70. The pixel photosensitive unit 10 is used for image acquisition and data readout. The beam-splitting structure includes multiple periods distributed in a periodic pattern. Each period includes a narrowband filter film 20, which is integrally deposited and grown on the pixel photosensitive unit 10. The narrowband filter film 20 is used to achieve tunability at the center wavelength of the desired band. The narrowband filter film 20 includes a mosaic-like distribution. The structure comprises multiple FP cavity structures; a transition layer 40 is integrally deposited and grown on the beam-splitting structure; 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 transition layer 40 is used to transition between the two film systems of narrowband filter film 20 and first cutoff filter film 30; a second cutoff filter film 60 is disposed on the first cutoff filter film 30, and the second cutoff filter film 60 is used to cut off the second interference band, which is different from the first interference band; a third cutoff filter film 70 is disposed on the second cutoff filter film 60, and the third cutoff filter film 70 is used to cut off the third interference band, which is different from both the first and second interference bands.

[0037] In a first embodiment of the present invention, the handheld multispectral imager includes an image sensor. This image sensor is constructed by integrally depositing a narrowband filter film onto a pixel photosensitive unit, an integrally depositing a transition layer onto the narrowband filter film, and an integrally depositing a first cutoff filter film onto 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 prevents external environmental contamination, providing better robustness, higher fabrication efficiency, and higher integration. By placing a second cutoff filter film on the first cutoff filter film and 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 narrowband filter film and the first cutoff filter film have different equivalent refractive indices, direct superposition would affect the peak transmittance. By placing 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 in the handheld multispectral imager 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 placement of the second cutoff filter film on the first cutoff filter film and the third cutoff filter film on the second cutoff filter film can broaden the cutoff range of the interference band. The transition layer between the narrowband filter film and the first cutoff filter film effectively improves the peak transmittance of the image sensor. Clear imaging can be achieved under both ordinary outdoor and indoor lighting conditions, with high image contrast. It has less dependence on external light sources and internal subsequent gain, and provides more complete restoration of information in each spectral band, effectively improving the spectral resolution of the handheld multispectral imager.

[0038] 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.

[0039] 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|H(LH)^S12nL(HL)^S1H L n1(W1)^S2n2(W2)^S3n3(W3)^S4|Air,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, W1, W2, and W3 all include high-refractive-index materials and low-refractive-index materials, 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. 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, 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 the second embodiment of the present invention, 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.

[0040] As a third embodiment of the present invention, a handheld multispectral imager is provided, the spectral imaging chip structure of which is the same as that of the second embodiment. In this spectral imaging chip structure, S1 = 5-7, S2, S3, S4 = 8-13, n1, n2, n3 = 0.5-2.5. Sub represents the substrate Si, Air represents air, H represents one of the 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.

[0041] As a fourth 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. In the film structure of the first cutoff filter film 30, W1 includes (0.5LH0.5L) or (0.5HL0.5H); the second cutoff filter film is disposed on the first cutoff filter film 30, and in the film structure of the second cutoff filter film 60, W2 includes (0.5LH0.5L) or (0.5HL0.5H); the third cutoff filter film 70 is disposed on the second cutoff filter film 60, and in the third cutoff filter film 70, W3 includes (0.5LH0.5L) or (0.5HL0.5H).

[0042] As a fifth 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 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.

[0043] As a sixth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager further defines the arrangement of the second cutoff filter film 60 based on the above embodiments. In this embodiment, the second cutoff filter film 60 is adhered to the first cutoff filter film 30. In this sixth embodiment of the present invention, the image sensor effectively blocks interference bands and simplifies the manufacturing process by adhering the second cutoff filter film to the first cutoff filter film. Compared with the prior art of externally bonded cutoff filter films, the image sensor provided by the present invention integrates the first cutoff filter film and the narrowband filter film into the image sensor, greatly improving quantum efficiency and spectral transmittance; adhering the second cutoff filter film to the first cutoff filter film effectively simplifies the manufacturing process and widens the cutoff range of interference bands, effectively improving the spectral resolution of the handheld multispectral imager.

[0044] As a seventh embodiment of the present invention, a handheld multispectral imager is provided, which further defines the arrangement of the second cutoff filter film 60 based on the above embodiments. In this embodiment, the second cutoff filter film 60 is integrally deposited and grown on the first cutoff filter film 30. By integrally depositing and growing the second cutoff filter film 60 on the first cutoff filter film 30, the second cutoff filter film can be integrated into the image sensor. This method has high spectral transmittance, which greatly improves quantum efficiency and spectral transmittance.

[0045] As an eighth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager further defines the arrangement of the third cutoff filter film 70 based on the above embodiments. In this embodiment, the third cutoff filter film 70 is adhered to the second cutoff filter film 60. In this eighth embodiment of the present invention, by adhering the third cutoff filter film to the second cutoff filter film, the image sensor can effectively broaden the cutoff range of the interference band and simplify the manufacturing process. Compared with the prior art of externally bonded cutoff filter films, the image sensor provided by the present invention, by adhering the third cutoff filter film to the second cutoff filter film, can effectively simplify the manufacturing process and broaden the cutoff range of the interference band, thereby effectively improving the spectral resolution of the handheld multispectral imager.

[0046] As a ninth embodiment of the present invention, a handheld multispectral imager is provided, which further defines the arrangement of the third cutoff filter film 70 based on the seventh embodiment. In this embodiment, the third cutoff filter film 70 is integrally deposited and grown on the second cutoff filter film 60. By integrally depositing and growing the third cutoff filter film 70 on the second cutoff filter film 60, the third cutoff filter film can be integrated into the image sensor. This method has high spectral transmittance, which greatly improves quantum efficiency and spectral transmittance.

[0047] As a tenth 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.

[0048] As an eleventh embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager is based on the tenth embodiment, with further definition of the first and second reflecting mirrors. 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, is located between the light-transmitting layer and the pixel photosensitive area, and also has a high reflectivity effect.

[0049] As a twelfth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager, based on the above embodiments, further defines the film thickness adjustment coefficient for any 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 for any 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 for any 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.

[0050] In the thirteenth embodiment of the present invention, by optimizing the design of any cutoff filter film, that is, by designing the film thickness adjustment coefficient of any 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.

[0051] As a fourteenth embodiment of the present invention, a handheld multispectral imager 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, 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).

[0052] As a fifteenth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager, based on the above embodiments, limits the film thickness adjustment coefficient of any cutoff filter film. In this embodiment, the film thickness adjustment coefficient n of any 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.

[0053] 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 5 As 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.

[0054] As a sixteenth 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.

[0055] In the sixteenth embodiment of the present invention, the handheld multispectral imager proposed in this embodiment has all the beneficial effects of the handheld multispectral imager in the first embodiment. Furthermore, by fabricating the narrowband filter's FP cavity structure and polarization filter structure in the same beam-splitting structure, it combines the advantages of polarization enhancement and spectral recognition, improving the accuracy of target recognition in complex background environments, reducing dependence on external light sources and internal subsequent gain, and providing more complete restoration of information in each spectral band. This effectively improves the spectral resolution of the handheld multispectral imager. Simultaneously, the structure is simple, the fabrication process is mature, and the algorithms for analyzing spectral and polarization information are simple. It can be applied in harsh and demanding environments, such as at night, under glare, or in foggy conditions, significantly expanding its application scenarios in areas such as security monitoring, military anti-camouflage applications, outdoor environmental monitoring, and smart agriculture.

[0056] As the seventeenth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager is based on the sixteenth 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.

[0057] In the seventeenth 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 the target's polarization information. Furthermore, based on the sixteenth embodiment of the present invention, other types of polarization filter structures can be derived and modified based on four-quadrant polarization.

[0058] As the eighteenth embodiment of the present invention, such as Figure 3As shown, a handheld multispectral imager is provided. Based on the sixteenth 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.

[0059] 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.

[0060] As the nineteenth embodiment of the present invention, a handheld multispectral imager is provided. Based on the sixteenth embodiment, the handheld multispectral imager 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.

[0061] In the nineteenth 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.

[0062] As a twentieth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager further defines the beam-splitting structure based on the above embodiments. 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.

[0063] As a twenty-first 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 the pixel photosensitive unit 10. By integrally depositing and growing multiple polarization filter structures on the pixel photosensitive unit 10, 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.

[0064] As the twenty-second embodiment of the present invention, such as Figure 4 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.

[0065] In the twenty-second 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 described in the above embodiments. There are no gaps between the first cutoff filter film, the narrowband filter film, and the pixel photosensitive unit, resulting in high spectral transmittance and reduced energy loss. The one-time fabrication process ensures integral molding, preventing external environmental contamination and providing better robustness. It also offers higher fabrication efficiency and integration, significantly improving quantum efficiency and spectral transmittance, and effectively enhancing the spectral resolution of the handheld multispectral imager.

[0066] As the twenty-third embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager is based on the twenty-second 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.

[0067] As the twenty-fourth embodiment of the present invention, a handheld multispectral imager is provided. This handheld multispectral imager is further defined based on the twenty-second 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.

[0068] 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.

[0069] 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.

[0070] 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 hand-held multi-spectral imager, characterized by, The handheld multispectral imager includes an image sensor, which comprises: A pixel photosensitive unit (10) is used to realize image acquisition and data readout; The beam-splitting structure includes multiple periods arranged in a periodic pattern. Each period includes a narrowband filter (20), which is integrally deposited and grown on the pixel photosensitive unit (10). 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 FP cavity structures and polarization filter structures are fabricated in the same beam-splitting structure. Each period also includes at least one full-transparency spectral structure, which 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, which is randomly arranged with the multiple polarization filter structures and the multiple FP cavity structures. Transition layer (40), the transition layer (40) is integrally deposited and grown on the spectral structure; The first cutoff filter film (30) is integrally deposited and grown on the transition layer (40). The first cutoff filter film (30) is used to cut off the first interference band. The transition layer (40) is used to transition between the two film systems, the narrowband filter film (20) and the first cutoff filter film (30). The second cutoff filter (60) is disposed on the first cutoff filter (30) and is used to cut off the second interference band, which is different from the first interference band. A third cutoff filter (70) is disposed on the second cutoff filter (60). The third cutoff filter (70) is used to cut off a third interference band, which is different from both the first interference band and the second interference band. The film structure of the image sensor is Sub|H(LH)^S12nL(HL)^S1 HL n1(W1)^S2n2(W2)^S3n3(W3)^S4|Air, H(LH)^S12nL(HL)^S1 H is the film structure of the narrowband filter (20), L is the film structure of the transition layer (40), W1, W2 and W3 all include high refractive index materials and low refractive index materials, n1(W1)^S2 is the film structure of the first cutoff filter film (30), n2(W2)^S3 is the film structure of the second cutoff filter film (60), n3(W3)^S4 is the film structure of the third cutoff filter film (70), H is a high refractive index material, L is a low refractive index material, S1, S2, S3 S4 represents the number of superpositions, n is the film thickness adjustment coefficient of the narrowband filter, n1 is the film thickness adjustment coefficient of the first cutoff filter (30), n2 is the film thickness adjustment coefficient of the second cutoff filter (60), and n3 is the film thickness adjustment coefficient of the third cutoff filter (70); the film thickness adjustment coefficients of the first cutoff filter (30), the second cutoff filter (60), and the third cutoff filter (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, In the membrane structure of the first cutoff filter membrane (30), W1 includes 0.5LH0.5L or 0.5HL0.5H; in the second cutoff filter membrane (60), W2 includes 0.5LH0.5L or 0.5HL0.5H; in the third cutoff filter membrane (70), W3 includes 0.5LH0.5L or 0.5HL0.5H.

3. The handheld multispectral imager according to claim 1 or 2, characterized in that, 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. 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.

4. The handheld multispectral imager according to claim 1, characterized in that, The second cutoff filter membrane (60) is attached to the first cutoff filter membrane (30).

5. The handheld multispectral imager according to claim 1, characterized in that, The second cutoff filter membrane (60) is integrally deposited and grown on the first cutoff filter membrane (30).

6. The handheld multispectral imager according to claim 4 or 5, characterized in that, The third cutoff filter membrane (70) is attached to the second cutoff filter membrane (60).

7. The handheld multispectral imager according to claim 5, characterized in that, The third cutoff filter membrane (70) is integrally deposited and grown on the second cutoff filter membrane (60).

8. 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.

9. 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, which is connected to the image sensor; A control circuit, comprising a processor and a communication module, wherein the processor is connected to the readout circuit and the communication module respectively.

Images