Spectral camera

Abstract

The present application relates to a spectrum camera, comprising: a housing having an opening; the spectrum chip module is positioned in the shell; the lens assembly is fixed with the shell through the opening and is used for focusing incident light onto the spectrum chip module; the spectrum chip module comprises a spectrum chip, the spectrum chip comprises a silicon-based substrate, the silicon-based substrate comprises a photoelectric sensing layer, and the photoelectric sensing layer comprises a plurality of pixels; the base material layer is arranged on the photoelectric sensing layer; the spectrum modulation layer is arranged on the base material layer, the spectrum modulation layer comprises a plurality of light filtering units arranged in an array mode, each light filtering unit comprises a plurality of light filtering sub-units, and the light filtering sub-units have different transmittance curves; wherein light incident to the spectrum chip is modulated by the spectrum modulation layer and the base material layer together.

Description

A spectral camera Technical Field

[0001] This application relates to the field of spectral modulation technology, specifically to a spectral camera. Background Technology

[0002] Spectral imaging has seen rapid development in recent years, enriching traditional imaging methods and providing unprecedented detail of objects. As a high-dimensional perception method, it plays an increasingly important role in fields such as precision agriculture, food safety inspection, environmental monitoring, and medical imaging.

[0003] The core of spectral imaging technology lies in the spectral chip, and the most important structure determining the imaging performance of the spectral chip is its optical modulation structure. In existing spectral cameras, various spectral chips employ different optical modulation structures. Taking the structure disclosed in prior art CN113497065A as an example, the optical modulation structure used in this patent is a filter film material, specifically a polyimide-based material. However, in this structure, it has been found that the modulation effect of this type of spectral chip on visible light within certain preset wavelength ranges is not ideal (e.g., the transmittance curve shown in Figure 3), making it impossible to obtain an ideal transmittance curve, thus resulting in unsatisfactory imaging performance in spectral cameras using this type of spectral chip. Summary of the Invention

[0004] In view of the problems existing in the prior art, the inventors added a base material layer to the existing spectral chip, so that the base material layer and the spectral modulation layer can jointly modulate the incident light and finally obtain an ideal transmittance curve.

[0005] Specifically, a spectroscopic camera includes:

[0006] The shell has an opening;

[0007] The spectral chip module is located inside the housing;

[0008] The lens assembly is fixed to the housing through the opening and focuses the incident light onto the spectral chip module;

[0009] in,

[0010] The spectral chip module includes:

[0011] A spectral chip, comprising: a silicon substrate including a photoelectric sensing layer comprising multiple pixels; a base material layer disposed on the photoelectric sensing layer; and a spectral modulation layer disposed on the base material layer, wherein the spectral modulation layer comprises multiple filter units arranged in an array, each filter unit comprising multiple filter sub-units, each filter sub-unit having a different transmittance curve; wherein light incident on the spectral chip is modulated by the spectral modulation layer and the base material layer.

[0012] Optionally, the base material layer has a first transmittance curve, wherein the shape of the first transmittance curve is designed such that the transmittance curve of the light incident on the spectral chip after being modulated by the spectral modulation material layer and the base material layer is more sensitive in the preset wavelength range than in the outside of the preset wavelength range.

[0013] Optionally, the transmittance of the first transmittance curve within a preset wavelength range is higher than the transmittance outside the preset wavelength range.

[0014] Optionally, if the waveform of the filter subunit within the preset wavelength range is plateau-shaped, the final transmittance curve after modulation will exhibit a peak within the preset wavelength range; or

[0015] If the waveform of the filter subunit has a peak within the preset wavelength range, and the final transmittance curve after modulation still shows a peak within the preset wavelength range, the full width at half maximum (FWHM) of the modulated peak is smaller than that of the peak before modulation; or

[0016] If the waveform of the filter subunit is concave within the preset wavelength range, the final transmittance curve after modulation will show a peak within the preset wavelength range.

[0017] Optionally, the base material layer is a colloidal curable film composed of a mixture of resin material, photoinitiator material, and solvent material; and / or

[0018] The filter subunit is a colloidal cured film composed of resin material, photoinitiator material, pigment, and solvent material.

[0019] Optionally, the base material layer is a single-layer structure.

[0020] Optionally, throughout the entire spectral chip, the sum of the thicknesses of each filter subunit and its corresponding base material layer in projection relation is equal; and

[0021] Within the same filter unit, the thickness of the base material layer corresponding to different filter sub-units is stepped.

[0022] Optionally, the base material layer includes:

[0023] A grid structure formed of a dielectric material, wherein the orthographic projection of each mesh of the grid structure onto the photoelectric sensing layer is aligned with the orthographic projection of one or more filter subunits onto the photoelectric sensing layer;

[0024] The base material is filled into the mesh, wherein the base material is the same in each mesh.

[0025] Optionally, the base material in each mesh of the mesh structure corresponds to a filter sub-unit, wherein the sum of the thicknesses of the base materials in all meshes and their corresponding filter sub-units is equal throughout the entire spectral chip; and within the same filter unit, the thicknesses of the base materials corresponding to different filter sub-units are stepped.

[0026] Optionally, the thickness of the filter subunit is in the range of 500-1000 nm, and the thickness of the base material layer is in the range of 50-500 nm.

[0027] Optionally,

[0028] The preset wavelength range is 500-650nm;

[0029] The transmittance of the first transmittance curve satisfies the following constraints: peak transmittance wavelength is 500-640nm, T(400nm-490nm)≥70%, T(585nm-620nm)≥90%, T(650nm-900nm)≥70%;

[0030] The filter unit comprises 3*3 filter sub-units C1-C9, and the transmittance curve of each filter sub-unit satisfies the following constraints:

[0031] TC1: Valley transmittance wavelength is 420-465nm, T(420nm-465nm)≤20%, T(515nm-900nm)≥80%;

[0032] TC2: Valley transmittance wavelength is 470-500nm, T(470nm-500nm)≤10%, T(525nm-900nm)≥90%;

[0033] TC3: Valley transmittance wavelength is 510-560nm, T(400nm-450nm)≥80%, T(510nm-560nm)≤20%; T(580nm-900nm)≥85%;

[0034] TC4: Valley transmittance wavelength is 585-615nm, T(415nm-480nm)≥80%, T(585nm-615nm)≤10%; T(650nm-900nm)≥75%;

[0035] TC5: Valley transmittance wavelength is 620-645nm, T(300nm-540nm) ≥80%, T(620nm-645nm) ≤10%; T(675nm-900nm) ≥85%;

[0036] TC6: Valley transmittance wavelength is 625-660nm, T(400nm-535nm) ≥80%, T(625nm-660nm) ≤10%; T(690nm-900nm) ≥85%;

[0037] TC7: Valley transmittance wavelength is 655-700nm; T(400nm-545nm) ≥80%; T(655nm-700nm) ≤20%; T(740nm-900nm) ≥85%;

[0038] TC8: Valley transmittance wavelength is 685-730nm, T(400nm-565nm) ≥80%, T(685nm-730nm) ≤10%; T(780nm-900nm) ≥85%;

[0039] TC9: Valley transmittance wavelength is 700-745nm, T(470nm-590nm) ≥80%, T(700nm-745nm) ≤40%; T(790nm-900nm) ≥80%;

[0040] After the optical signal is modulated by both the spectral modulation layer and the base material layer, the transmittance of the final transmittance curves obtained on each spectral modulation channel A1-A9 satisfies the following constraints:

[0041] TA1: Peak transmittance wavelength is 500nm-650nm, T(430nm-460nm)≤10%, T(500nm-650nm)≥60%, T(650nm-900nm)≥55%;

[0042] TA2: Peak transmittance wavelength is 550-620nm, T(460nm-500nm)≤10%, T(550nm-620nm)≥80%, T(650nm-900nm)≥65%;

[0043] TA3: Peak transmittance wavelength is 575-635nm, T(510nm-550nm)≤15%, T(575nm-635nm)≥70%, T(650nm-900nm)≥60%;

[0044] TA4: Valley transmittance wavelength is 550-620nm, T(400nm-540nm)≥20%, T(550nm-620nm)≤20%, T(640nm-900nm)≥55%;

[0045] TA5: Valley transmittance wavelength is 615-650nm, T(300nm-565nm) ≥60%, T(615nm-650nm) ≤20%, T(675nm-900nm) ≥60%;

[0046] TA6: Valley transmittance wavelength is 600-670nm, T(400nm-560nm) ≥60%, T(600nm-670nm) ≤20%, T(700nm-900nm) ≥60%;

[0047] TA7: Valley transmittance wavelength is 630-700nm, T(400nm-575nm) ≥60%, T(630nm-700nm) ≤20%, T(735nm-900nm) ≥60%;

[0048] TA8: Valley transmittance wavelength is 635-735nm, T(400nm-590nm) ≥60%, T(635nm-735nm) ≤20%, T(780nm-900nm) ≥60%;

[0049] TA9: Peak transmittance wavelength is 500-625nm, T(300nm-480nm)≤60%, T(500nm-625nm)≥60%, T(685nm-750nm)≤40%, T(810nm-900nm)≥60%.

[0050] Optionally, there is at least one inclined overlap region relative to the silicon substrate between each filter subunit and its adjacent filter subunit, the orthographic projection of the inclined overlap region on the silicon substrate spanning two adjacent pixels.

[0051] Optionally, the filter subunit is frustum-shaped.

[0052] Optionally, two adjacent filter subunits are respectively a regular square frustum and an inverted square frustum.

[0053] Optionally, the angle between the beveled overlap area and the silicon substrate is between 60 degrees and 90 degrees.

[0054] Optionally, the thickness of the filter subunit is in the range of 500-1000 nm.

[0055] Optionally, the filter subunit is a colloidal cured film composed of resin material, photoinitiator material, pigment and solvent material.

[0056] Optionally, each filter unit includes 3*3 filter subunits C1-C9, wherein the first row along the first direction consists of C1-C3, the second row along the first direction consists of C4-C6, and the third row along the first direction consists of C7-C9, wherein C2, C4, C6 and C8 are regular square frustums, and C1, C3, C5, C7 and C9 are inverted square frustums.

[0057] Optionally, the transmittance curve of the light incident on the multispectral chip after being modulated by the spectral modulation material layer satisfies the following constraint:

[0058] TC1: Valley transmittance wavelength is 400-550nm; T(430nm-495nm)≤10%; T(550nm-900nm)≥70%;

[0059] TC2: Valley transmittance wavelength is 400-575nm; T (420nm-550nm) ≤15%; T (585nm-900nm) ≥65%;

[0060] TC3: Valley transmittance wavelength is 400-580nm; T(455nm-550nm)≤15%; T(600nm-900nm)≥75%;

[0061] TC4: Valley transmittance wavelength is 500-680nm; T(400nm-500nm) ≥ 65%; T(580nm-645nm) ≤ 10%; T(700nm-900nm) ≥ 65%;

[0062] TC5: Valley transmittance wavelength is 500-675nm; T(400nm-500nm) ≥50%; T(550nm-650nm) ≤10%; T(700nm-900nm) ≥60%;

[0063] TC6: Valley transmittance wavelength is 550-700nm; T(400nm-535nm)≥65%; T(600nm-665nm)≤10%; T(700nm-900nm)≥75%;

[0064] TC7: Valley transmittance wavelength is 550-750nm; T(400nm-550nm) ≥65%; T(630nm-725nm) ≤10%; T(800nm-900nm) ≥75%;

[0065] TC8: Valley transmittance wavelength is 550-750nm; T(460nm-545nm)≥55%; T(625nm-740nm)≤10%; T(775nm-900nm)≥55%;

[0066] TC9: Valley transmittance wavelength is 600-700nm; T(465nm-540nm)≥70%; T(680nm-745nm)≤10%; T(785nm-900nm)≥70%.

[0067] Optionally, the spectral chip further includes a first protective film layer disposed on the spectral modulation layer, wherein the first protective film layer includes a plurality of sub-protective film layers, and at least two filter sub-units in the same filter unit are covered by the same sub-protective film layer.

[0068] Optionally, at least two adjacent filter sub-units in the same filter unit are covered by the same sub-protective film layer.

[0069] Optionally, the filtering unit consists of M rows and N columns of filtering sub-units.

[0070] The first protective film layer includes M sub-protective film layers, where the m-th sub-protective film layer covers the N filter sub-units in the m-th row, where m traverses from 1 to M, and M and N are both natural numbers greater than or equal to 2.

[0071] Optionally, the filter unit includes 3*3 filter sub-units C1-C9, wherein the first row along the first direction consists of C1-C3, the second row along the first direction consists of C4-C6, and the third row along the first direction consists of C7-C9.

[0072] The first protective film layer includes three sub-protective film layers, wherein the first sub-protective film layer covers C1-C3, the second sub-protective film layer covers C4-C6, and the third sub-protective film layer covers C7-C9.

[0073] Optionally, the filtering unit consists of M rows and N columns of filtering sub-units.

[0074] The first protective film layer includes N sub-protective film layers, where the nth sub-protective film layer covers the M filter sub-units in the nth column, where n traverses from 1 to N, and M and N are both natural numbers greater than or equal to 2.

[0075] Optionally, the filter unit includes 3*3 filter sub-units C1-C9, wherein the first row along the first direction consists of C1-C3, the second row along the first direction consists of C4-C6, and the third row along the first direction consists of C7-C9.

[0076] The first protective film layer includes three sub-protective film layers, wherein the first sub-protective film layer covers C1, C4 and C7, the second sub-protective film layer covers C2, C5 and C8, and the third sub-protective film layer covers C3, C6 and C9.

[0077] Optionally, at least two non-adjacent filter sub-units in the same filter unit are covered by the same sub-protective film layer.

[0078] Optionally, the filtering unit consists of M rows and N columns of filtering sub-units.

[0079] The first protective film layer includes a first sub-protective film layer and a second sub-protective film layer, wherein the first sub-protective film layer covers the even-numbered filter sub-units, and the second sub-protective film layer covers the odd-numbered filter sub-units, wherein the odd and even numbers are calculated from the first row and first column to the M-th row and N-th column.

[0080] Optionally, the filter unit includes 3*3 filter sub-units C1-C9, wherein the first row along the first direction contains C1-C3, the second row contains C4-C6, and the third row contains C7-C9.

[0081] The first protective film layer includes two sub-protective film layers. The first sub-protective film layer covers the C2, C4, C6, and C8 filter sub-units, and the second sub-protective film layer covers the C1, C3, C5, C7, and C9 filter sub-units.

[0082] Optionally, the thickness of the first protective film layer ranges from 10 to 500 nm.

[0083] Optionally, the spectral chip further includes:

[0084] A second protective film layer is disposed between the photoelectric sensing layer and the base material layer.

[0085] Optionally, the thickness of the second protective film layer ranges from 10 to 500 nm.

[0086] Optionally, the spectral camera further includes a filter structure disposed on the first protective film layer.

[0087] Optionally, the spectral chip module further includes:

[0088] The microlens layer disposed on the filter structure includes a microlens array composed of multiple microlenses, wherein the orthographic projection of each microlens on the silicon substrate is aligned with the orthographic projection of one of the multiple filter subunits on the silicon substrate.

[0089] Optionally, the filtering structure is a filter.

[0090] Optionally, the filter material is glass, plastic, or optical film material.

[0091] Optionally, the thickness of the filter is 0.05mm-0.5mm.

[0092] Optionally, the spectral camera further includes a circuit board, on which the spectral chip is disposed and electrically connected.

[0093] Optionally, the spectral chip module further includes a support member disposed on the circuit board, wherein the filter is bonded to the spectral modulation layer by means of the support member.

[0094] Optionally, the filter structure is a filter coating, and the material is an oxide, a fluoride, or a mixture of both.

[0095] Optionally, the filter coating is deposited on the surface of the microlens facing the silicon substrate or on the surface of the first protective film layer facing the microlens.

[0096] Optionally, the spectral chip module further includes a third protective film layer disposed between the filter coating and the microlens layer.

[0097] Optionally, the filter structure is a bandpass filter structure, wherein the lower cutoff wavelength of the bandpass filter structure is 350 nm and the upper cutoff wavelength is 950 nm.

[0098] Optionally, the spectral camera further includes a computing unit and an interface unit, wherein the computing unit is used to receive electrical signals from the spectral sensing layer and invert them into a color image based on the electrical signals;

[0099] The interface unit includes an input interface and an output interface, wherein the input interface is used to provide power to drive the spectral camera, and the output interface is used to connect to an output device.

[0100] Optionally, the computing unit and the interface unit are disposed on the circuit board.

[0101] In this application, the spectral chip used in the spectral camera includes a base material layer, which, together with the spectral modulation layer, modulates the incident light, making the spectral camera more sensitive in the band of interest and producing better imaging results. Attached Figure Description

[0102] The disclosure of this application will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this application. Wherein:

[0103] Figure 1 is a schematic diagram of the structure of a spectral camera according to an embodiment of this application;

[0104] Figure 2 is an exploded view of a spectral chip module according to an embodiment of this application;

[0105] Figure 3 shows the light transmittance curves of a 9-channel spectral chip based on existing technology;

[0106] Figure 4 is a light transmittance curve of the base material layer according to an embodiment of this application;

[0107] Figure 5 is a light transmittance curve of a structure with a base material layer after modulation according to an embodiment of this application;

[0108] Figure 6 is a schematic diagram of a preferred structure of a spectral chip according to an embodiment of this application;

[0109] Figure 7 is a schematic diagram showing the overlapping region in the light transmittance curves shown in Figure 3;

[0110] Figure 8 is a schematic diagram showing the overlapping region in the light transmittance curves shown in Figure 5;

[0111] Figure 9 is a schematic diagram of a preferred structure of a spectral chip according to another embodiment of this application;

[0112] Figure 10 is a partial schematic diagram of the structure of the multispectral chip shown in Figure 9;

[0113] Figure 11 is a light transmittance curve after structural modulation of a filter subunit having a regular square truncated pyramid shape and an inverted square truncated pyramid shape according to another embodiment of this application.

[0114] Figure 12 is a light transmittance curve of a filter subunit having a base material layer and having the shapes of a regular square truncated pyramid and an inverted square truncated pyramid according to another embodiment of this application after structural modulation.

[0115] Figures 13(a) and 13(b) are schematic diagrams of the structure of a spectroscopic camera according to the prior art;

[0116] Figure 14 is a partial structural schematic diagram of a spectral camera according to an embodiment of the present application;

[0117] Figures 15 to 20 are schematic flowcharts of a method for fabricating a spectral chip according to an embodiment of this application. Detailed Implementation

[0118] Some embodiments of this application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of this application and are not intended to limit the scope of protection of this application.

[0119] In the description of this application, "module" and "processor" can include hardware, software, or a combination of both. A module may include hardware circuitry, various suitable sensors, communication ports, and memory, and may also include software components, such as program code, or a combination of software and hardware. A processor may be a central processing unit, microprocessor, image processor, digital signal processor, or any other suitable processor. The processor has data and / or signal processing capabilities. The processor may be implemented in software, in hardware, or a combination of both. Computer-readable storage media includes any suitable medium capable of storing program code, such as magnetic disks, hard disks, optical disks, flash memory, read-only memory, random access memory, etc.

[0120] The term "A and / or B" refers to all possible combinations of A and B, such as only A, only B, or A and B. The terms "at least one A or B" or "at least one of A and B" have a similar meaning to "A and / or B" and can include only A, only B, or A and B. The singular forms of the terms "a" or "this" can also include plural forms.

[0121] The specific embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0122] This application provides a spectroscopic camera. In one embodiment, as shown in FIG1, FIG1 is a structural diagram of the spectroscopic camera of this application. The spectroscopic camera includes:

[0123] The shell has an opening;

[0124] The spectral chip module is located inside the housing;

[0125] The lens assembly is fixed to the housing through the opening and focuses the incident light onto the spectral chip module;

[0126] in,

[0127] The spectral chip module includes:

[0128] A spectral chip, comprising: a silicon substrate including a photoelectric sensing layer comprising multiple pixels; a base material layer disposed on the photoelectric sensing layer; and a spectral modulation layer disposed on the base material layer, wherein the spectral modulation layer comprises multiple filter units arranged in an array, each filter unit comprising multiple filter sub-units, each filter sub-unit having a different transmittance curve; wherein light incident on the spectral chip is modulated by the spectral modulation layer and the base material layer.

[0129] In one example, the lens assembly includes at least two optical lenses, such as those of a digital camera or a COB (optical lens), and is positioned on top of the spectral chip module to focus incident light onto the center of the spectral chip module.

[0130] As shown in Figure 2, Figure 2 is an exploded view of the spectral chip module in the spectral camera of this application. It should be noted that, for simplicity, Figure 1 does not show all the layers included in Figure 2.

[0131] In this example, the filter unit is a 3*3 array structure, and each filter unit includes 9 filter sub-units, each with a different transmittance curve.

[0132] In one example, the material of the filter subunit is a colloidal cured film composed of resin material, photoinitiator material, pigment, and solvent material.

[0133] The resin materials include soluble resins, such as phenolic resins, polyurethane resins, polyvinyl alcohol resins, and maleic anhydride resins; and photocurable resins, such as polyimide resins, polyvinyl alcohol resins, epoxy resins, and styrene resins.

[0134] Photoinitiator materials include benzophenones, alkyl phenyl ketones, benzoin and its derivatives, iodonium salts, and iron aromatics.

[0135] Pigments include aniline pigments, phthalocyanine pigments, azo pigments, and pyrrole pigments.

[0136] Solvent-based materials include ethylene glycol methyl ethers, propylene glycol methyl ether acetates, triethylene glycol methyl ethers, and ethyl 3-ethoxypropionate.

[0137] By selecting and proportioning these materials, the transmittance curves of each filter subunit shown in Figure 3 can be obtained.

[0138] In some applications, due to the limitations of the materials themselves, the transmittance curves of the modulation channels (as shown in Figure 3, in a spectral chip with a 3*3 array of filter units, the 9 spectral modulation channels are made of different spectral modulation materials, and the 9 spectral modulation materials have the transmittance curves shown in the figure) cannot achieve a better linear response in certain key wavelength ranges (key bands, such as those used in cameras and other shooting tools for visible light imaging, where the key wavelength range is usually 500-650nm). During color reproduction, the response of such a structure to the key band will be affected by interference from bands outside that band, especially under low light conditions, which makes it impossible to provide accurate spectral capture.

[0139] Therefore, in a preferred embodiment of this application, the spectral chip further includes a base material layer disposed between the photoelectric sensing layer and the spectral modulation layer, wherein the linear shape of the first transmittance curve is designed such that the transmittance curve of the light incident on the multispectral chip, after being modulated by the spectral modulation layer and the base material layer, is more sensitive in a preset wavelength range than in a response outside the preset wavelength range.

[0140] Unlike existing technologies, this application adds a base material layer, and the incident light is modulated sequentially by the spectral modulation layer and the base material layer.

[0141] The inventors introduced a base material layer into the original structure and designed the shape of its transmittance curve (hereinafter referred to as the first transmittance curve), so that the final transmittance curve obtained by the incident light in each spectral modulation channel is more sensitive in the preset wavelength range than in the response outside the preset wavelength range. In essence, this makes the transmittance of the spectral chip for light in the key band (which can also be called the preset wavelength range from a design perspective) higher than the transmittance for light outside the range.

[0142] In a preferred embodiment, the transmittance of the first transmittance curve within a preset wavelength range is higher than the transmittance outside the preset wavelength range.

[0143] Figure 4 shows the first transmittance curve designed for the visible light band 500-650nm. Specifically, the transmittance of the first transmittance curve satisfies the following constraints: peak transmittance wavelength is 500-640nm, T(400nm-490nm)≥70%, T(585nm-620nm)≥90%, and T(650nm-900nm)≥70%.

[0144] The process of modulating the transmittance curves of each filter sub-unit using the first transmittance curve is mathematically equivalent to multiplying the transmittance of the two sub-units at the same wavelength as a new transmittance, thus obtaining a wavelength-transmittance function. Alternatively, it can be described as using the transmittance on the first transmittance curve as a modulation factor to modulate the transmittance on the transmittance curves of each filter sub-unit. This design of the first transmittance curve allows for modulation of the transmittance curve within a preset wavelength range, as shown in Figure 4. For example, it can improve or alleviate situations where some modulation channels exhibit plateaus or even dips within this wavelength range.

[0145] Specifically, if the waveform of the filter subunit within the preset wavelength range is plateau-shaped, the final transmittance curve after modulation will show a peak in the waveform within the preset wavelength range; if the waveform of the filter subunit within the preset wavelength range has a peak, the final transmittance curve after modulation will still show a peak in the waveform within the preset wavelength range, and the full width at half maximum (FWHM) of the peak after modulation will be smaller than that of the peak before modulation; if the waveform of the filter subunit within the preset wavelength range is concave-shaped, the final transmittance curve after modulation will show a peak in the waveform within the preset wavelength range.

[0146] The following explanation uses C1-C9 in the diagram as an example. The transmittance curves of each filter sub-unit satisfy the following constraints:

[0147] TC1: Valley transmittance wavelength is 420-465nm, T(420nm-465nm)≤20%, T(515nm-900nm)≥80%;

[0148] TC2: Valley transmittance wavelength is 470-500nm, T(470nm-500nm)≤10%, T(525nm-900nm)≥90%;

[0149] TC3: Valley transmittance wavelength is 510-560nm, T(400nm-450nm)≥80%, T(510nm-560nm)≤20%; T(580nm-900nm)≥85%;

[0150] TC4: Valley transmittance wavelength is 585-615nm, T(415nm-480nm)≥80%, T(585nm-615nm)≤10%; T(650nm-900nm)≥75%;

[0151] TC5: Valley transmittance wavelength is 620-645nm, T(300nm-540nm) ≥80%, T(620nm-645nm) ≤10%; T(675nm-900nm) ≥85%;

[0152] TC6: Valley transmittance wavelength is 625-660nm, T(400nm-535nm) ≥80%, T(625nm-660nm) ≤10%; T(690nm-900nm) ≥85%;

[0153] TC7: Valley transmittance wavelength is 655-700nm; T(400nm-545nm) ≥80%; T(655nm-700nm) ≤20%; T(740nm-900nm) ≥85%;

[0154] TC8: Valley transmittance wavelength is 685-730nm, T(400nm-565nm) ≥80%, T(685nm-730nm) ≤10%; T(780nm-900nm) ≥85%;

[0155] TC9: Valley transmittance wavelength is 700-745nm, T(470nm-590nm) ≥80%, T(700nm-745nm) ≤40%; T(790nm-900nm) ≥80%.

[0156] After modulation of the first transmittance curve shown in Figure 4, the linear shape shown in Figure 5 is obtained:

[0157] The transmittance of the final transmittance curves obtained for the incident light in each spectral modulation channel A1-A9 satisfies the following constraints:

[0158] TA1: Peak transmittance wavelength is 500nm-650nm, T(430nm-460nm)≤10%, T(500nm-650nm)≥60%, T(650nm-900nm)≥55%;

[0159] TA2: Peak transmittance wavelength is 550-620nm, T(460nm-500nm)≤10%, T(550nm-620nm)≥80%, T(650nm-900nm)≥65%;

[0160] TA3: Peak transmittance wavelength is 575-635nm, T(510nm-550nm)≤15%, T(575nm-635nm)≥70%, T(650nm-900nm)≥60%;

[0161] TA4: Valley transmittance wavelength is 550-620nm, T(400nm-540nm)≥20%, T(550nm-620nm)≤20%, T(640nm-900nm)≥55%;

[0162] TA5: Valley transmittance wavelength is 615-650nm, T(300nm-565nm) ≥60%, T(615nm-650nm) ≤20%, T(675nm-900nm) ≥60%;

[0163] TA6: Valley transmittance wavelength is 600-670nm, T(400nm-560nm) ≥60%, T(600nm-670nm) ≤20%, T(700nm-900nm) ≥60%;

[0164] TA7: Valley transmittance wavelength is 630-700nm, T(400nm-575nm) ≥60%, T(630nm-700nm) ≤20%, T(735nm-900nm) ≥60%;

[0165] TA8: Valley transmittance wavelength is 635-735nm, T(400nm-590nm) ≥60%, T(635nm-735nm) ≤20%, T(780nm-900nm) ≥60%;

[0166] TA9: Peak transmittance wavelength is 500-625nm, T(300nm-480nm)≤60%, T(500nm-625nm)≥60%, T(685nm-750nm)≤40%, T(810nm-900nm)≥60%.

[0167] In this application, by introducing a base material layer with a transmittance curve designed for a preset wavelength range, the transmittance curve of the original light modulation subunit is modulated. This optimizes the response of the spectral camera to the preset wavelength range, improves image quality, reduces interference from other bands (the presence of the base material layer reduces the transmittance of light outside the preset wavelength range), and ensures accurate color reproduction during shooting. Even if the application scenario changes (the key wavelength changes), only the transmittance curve of a single base layer needs to be designed for the new target wavelength, rather than adjusting the transmittance curves of multiple filter subunits in a coordinated manner.

[0168] The following explains how to achieve the transmittance curve designed for the base material layer. The inventor's idea is to make it compatible with the materials and processes of the filter subunit.

[0169] In this application, the material of the filter subunit is a colloidal cured film composed of resin material, photoinitiator material, pigment and solvent material.

[0170] The resin materials include soluble resins, such as phenolic resins, polyurethane resins, polyvinyl alcohol resins, and maleic anhydride resins; and photocurable resins, such as polyimide resins, polyvinyl alcohol resins, epoxy resins, and styrene resins.

[0171] Photoinitiator materials include benzophenones, alkyl phenyl ketones, benzoin and its derivatives, iodonium salts, and iron aromatics.

[0172] Pigments include aniline pigments, phthalocyanine pigments, azo pigments, and pyrrole pigments.

[0173] Solvent-based materials include ethylene glycol methyl ethers, propylene glycol methyl ether acetates, triethylene glycol methyl ethers, and ethyl 3-ethoxypropionate.

[0174] By selecting and proportioning these materials, the transmittance curves of each of the aforementioned filter sub-units can be obtained.

[0175] Based on this, the base material layer is selected to be a colloidal curable film made of resin material, photoinitiator material and solvent material.

[0176] As mentioned above, the base material layer is a monolithic structure, meaning it is deposited as a single layer on the photoelectric sensing layer, covering it. However, in this case, when light exits from a certain filter unit and enters the base material layer, it can be scattered to areas outside the corresponding region of the base material layer, resulting in crosstalk. This is particularly pronounced when the base material layer is thick.

[0177] Therefore, this application provides another preferred structure. Specifically, the base material layer includes:

[0178] A grid structure formed of a dielectric material, wherein the orthographic projection of each mesh of the grid structure onto the photoelectric sensing layer is aligned with the orthographic projection of one or more filter subunits onto the photoelectric sensing layer;

[0179] The base material is filled into the mesh, wherein the base material is the same in each mesh.

[0180] The medium material is preferably a light-absorbing material, such as the black matrix commonly used in the display panel industry.

[0181] As those skilled in the art can anticipate, the addition of a base material layer reduces the energy utilization of light, a situation that is further highlighted in embodiments with a grid structure formed by light-absorbing materials.

[0182] Typically, the solution that comes to mind is to reduce the thickness of the base material layer. However, if the base layer is too thin, it will be impossible to effectively modulate the key bands.

[0183] Therefore, in one embodiment, experiments revealed that the thickness of the base layer ranges from 50 to 500 nm, and the thickness of the modulation layer ranges from 500 to 1000 nm. Within this range, the spectral modulation channels of the base layer and modulation layer are advantageous for fabrication and can achieve better spectral modulation performance. A base layer thickness exceeding 500 nm increases the optical path length of the modulation channel, leading to spectral crosstalk between adjacent pixels in the photoelectric sensing layer. For the modulation layer, if its thickness is less than 500 nm, it loses its broadband modulation capability and cannot achieve the ideal modulation line shape; while if the modulation layer thickness exceeds 1000 nm, it makes the fabrication process difficult and, in addition to increasing spectral crosstalk, also reduces the transmittance of the modulation line.

[0184] However, this overall adjustment method does not take into account the differences in materials of different filter sub-units (e.g., different wavelengths of light scatter the same material to different degrees). A more preferred embodiment is given below.

[0185] In embodiments where the base material layer is a single layer, within the same filter unit of the entire spectral chip, the thickness of the base material layer corresponding to different filter subunits is stepped. For example, as shown in Figure 6, where Figure 6(a) is a top view of the spectral chip and Figure 6(b) is a cross-sectional view along the dashed line in the figure. As can be seen from Figure 6(b), the thickness of the base material region corresponding to C1 > the thickness of the base material region corresponding to C2 > the thickness of the base material region corresponding to C3 > the thickness of the base material region corresponding to C4 > the thickness of the base material region corresponding to C5 > the thickness of the base material region corresponding to C6 > the thickness of the base material region corresponding to C7 > the thickness of the base material region corresponding to C8 > the thickness of the base material region corresponding to C9. The overall base material layer is stepped.

[0186] As will be discussed in the process section later, the thickness varies depending on which filter sub-unit is fabricated first; the thickness of the corresponding base material region fabricated first is greater than that of the corresponding base material region fabricated later. Of course, the overall thickness of the base layer can still be controlled within the range of 50-500nm.

[0187] In the specific process, filter sub-units corresponding to wavelength ranges insensitive to scattering by the base layer material can be selected as C1 (made first), and filter sub-units corresponding to wavelength ranges sensitive to scattering by the base layer material can be selected as C9 (made later). This takes into account the crosstalk problem. At the same time, for the subsequent device flatness, the sum of the thickness of each filter sub-unit and the thickness of its corresponding base material layer region in the projection relationship is equal. Of course, the thickness of the modulation layer can still be controlled within 500-1000nm. In this way, with the total thickness being the same, the thickness ratio of each filter sub-unit to the corresponding base layer material can be varied, which is equivalent to the material ratio in the vertical direction being varied in each channel. This increases the means to adjust the transmittance curve shape, thereby enabling a more refined obtaining of the desired curve shape.

[0188] In the above-described mesh structure implementation, the above concept can also be realized. In the entire spectral chip, the sum of the thickness of the base material in all meshes and the thickness of the corresponding filter sub-units are equal; and in the same filter unit, the thickness of the base material corresponding to different filter sub-units is stepped.

[0189] On the other hand, both the transmittance curves of existing spectral chips (Figure 3) and the transmittance curves of spectral chips after adding the aforementioned basic material layer of this application (Figure 5) show aliasing in at least some channels within certain wavelength ranges. This aliasing phenomenon becomes more severe with the increase of the number of channels.

[0190] Figures 7 and 8 show the corresponding aliasing regions based on Figures 3 and 5, respectively (this phenomenon exists even in the aforementioned preset wavelength region after the addition of the base material layer). This results in low spectral resolution, making it difficult to accurately identify and modulate spectral signals, thus limiting the application of spectral chips in complex environments.

[0191] Typically, when fabricating each filter subunit, the desired ideal morphology is vertical or nearly vertical. Researchers have explored various methods for fabricating vertical or near-vertical filter subunits. However, the inventors of this application discovered through experimentation that when the edges of the filter subunits are inclined—that is, when adjacent filter subunits have an overlap area (inclined interface)—the waveforms in the aliasing region shown in Figure 7 or Figure 8 will demix. This provides the inventors with a new approach to further optimize the transmittance curve.

[0192] Therefore, in one embodiment of this application, within the same filter unit, two adjacent filter sub-units are a combination of a regular square frustum and an inverted square frustum, forming a sloping overlapping area. Note that "regular" and "inverted" are relative concepts. In this application, a regular square frustum refers to a sub-unit whose surface area closer to the photosensitive layer is larger than its surface area farther from the photosensitive layer; that is, relative to the photosensitive layer, the filter sub-unit is smaller at the top and larger at the bottom. An inverted square frustum refers to a sub-unit whose surface area closer to the photosensitive layer is smaller than its surface area farther from the photosensitive layer; that is, relative to the photosensitive layer, the filter sub-unit is larger at the top and smaller at the bottom.

[0193] For example, as shown in Figure 9, where Figure 9(a) is a top view of the spectral chip and Figure 9(b) is a cross-sectional view along the dotted line in the figure. As can be seen from Figure 9(b), C2 is a regular trapezoid (the shape of the cross-section, in a three-dimensional concept, corresponds to a regular square frustum), and the adjacent C1 and C3 are inverted trapezoids (the shape of the cross-section, in a three-dimensional concept, corresponds to an inverted square frustum), and an overlap area is formed between adjacent filter sub-units.

[0194] Please note that "regular" and "inverted" are relative concepts. In this application, a regular square truncated pyramid refers to a surface whose area is larger than the area of ​​the surface away from the photoelectric sensing layer, meaning that the filter subunit is smaller at the top and larger at the bottom relative to the photoelectric sensing layer. An inverted square truncated pyramid refers to a surface whose area is smaller than the area of ​​the surface away from the photoelectric sensing layer, meaning that the filter subunit is larger at the top and smaller at the bottom relative to the photoelectric sensing layer.

[0195] This structure can achieve such a modulation effect. As shown in Figure 10, taking C1-C3 as an example, the light entering pixel P1 is modulated by C1 and C2 (the R1 area to the left of the dashed line L1) (and also by the underlying base material layer below, the same below); the light entering pixel P3 is modulated by C3 and C2 (the R2 area to the right of the dashed line L2); the light entering pixel P2 is modulated by C1 (the R3 area to the right of the dashed line L3), C2 and C3 (the R4 area to the left of the dashed line L4).

[0196] The above examples use regular and inverted square truncated pyramids as illustrations; however, this application is not limited to these. Any truncated pyramid structure is acceptable. That is, a common modulation effect can be achieved when a filter subunit and its adjacent filter subunits have at least one beveled overlap area. For example, C1 and C2, C4 each have beveled overlap areas. Those skilled in the art, guided by the teachings of this application, can adjust the area and slope of the overlap area to ensure that the light entering each pixel is modulated by at least two different modulation subunits, thereby finely adjusting the linearity of the light transmittance curve entering the pixel and alleviating aliasing at certain wavelengths.

[0197] Furthermore, although the frustum-shaped filter subunits in the above example coexist with the base material layer, this application is not limited to this. The frustum-shaped filter subunits can be used independently (i.e., in a structure without a base layer, the filter subunits are frustum-shaped) to achieve their own effects. Specifically, the linearity of the transmittance curves of each channel can be more finely adjusted by adjusting the area and slope of the overlap area, thereby alleviating the aliasing of the transmittance curves at certain wavelengths.

[0198] In a preferred example, the angle between the beveled overlap area and the surface of the spectral modulation layer is between 60 and 90 degrees.

[0199] The structure shown in Figure 10 can be combined with either a spectral chip structure without a base material layer or with a spectral chip structure with a base material layer. Specifically, the transmittance curves of each channel can be more precisely adjusted by changing the area and slope of the overlap region, thereby mitigating aliasing of the transmittance curves at certain wavelengths. In a preferred example, the angle between the sloped overlap region and the surface of the spectral modulation material layer is between 60 and 90 degrees.

[0200] Figure 11 shows the transmittance curves of the incident light in each spectral modulation channel A1-A9 when applied to a spectral chip structure without a base material layer. The transmittance satisfies the following constraints:

[0201] TA1: Valley transmittance wavelength is 400-550nm; T(430nm-495nm)≤10%; T(550nm-900nm)≥70%;

[0202] TA2: Valley transmittance wavelength is 400-575nm; T (420nm-550nm) ≤15%; T (585nm-900nm) ≥65%;

[0203] TA3: Valley transmittance wavelength is 400-580nm; T(455nm-550nm)≤15%; T(600nm-900nm)≥75%;

[0204] TA4: Valley transmittance wavelength is 500-680nm; T(400nm-500nm) ≥ 65%; T(580nm-645nm) ≤ 10%; T(700nm-900nm) ≥ 65%;

[0205] TA5: Valley transmittance wavelength is 500-675nm; T(400nm-500nm) ≥50%; T(550nm-650nm) ≤10%; T(700nm-900nm) ≥60%;

[0206] TA6: Valley transmittance wavelength is 550-700nm; T(400nm-535nm)≥65%; T(600nm-665nm)≤10%; T(700nm-900nm)≥75%;

[0207] TA7: Valley transmittance wavelength is 550-750nm; T(400nm-550nm) ≥65%; T(630nm-725nm) ≤10%; T(800nm-900nm) ≥75%;

[0208] TA8: Valley transmittance wavelength is 550-750nm; T(460nm-545nm)≥55%; T(625nm-740nm)≤10%; T(775nm-900nm)≥55%;

[0209] TA9: Valley transmittance wavelength is 600-700nm; T(465nm-540nm)≥70%; T(680nm-745nm)≤10%; T(785nm-900nm)≥70%.

[0210] Comparing Figure 11 and Figure 7, it can be seen that the combination of regular and inverted square truncated pyramid shapes helps to separate partially overlapping transmittance curves, thereby improving the distinction between different spectra and enhancing the effect of spectral modulation.

[0211] Figure 12 shows the transmittance curves of the incident light in each spectral modulation channel A1-A9 when applied to a spectral chip structure with a base material layer. The transmittance satisfies the following constraints:

[0212] TA1: Peak transmittance wavelength is 520-640nm; T(420nm-495nm)≤10%; T(580nm-625nm)≥55%; T(670nm-900nm)≥50%;

[0213] TA2: Peak transmittance wavelength is 570-645nm; T(425nm-550nm) ≤10%; T(600nm-630nm) ≥70%; T(670nm-900nm) ≥55%;

[0214] TA3: Peak transmittance wavelength is 575-645nm; T(460nm-555nm)≤15%; T(580nm-620nm)≥70%; T(660nm-900nm)≥55%;

[0215] TA4: Valley transmittance wavelength is 550-650nm; T (400nm-500nm) ≥ 45%; T (580nm-645nm) ≤ 10%; T (700nm-900nm) ≥ 50%;

[0216] TA5: Valley transmittance wavelength is 550-675nm; T(425nm-500nm) ≥35%; T(550nm-665nm) ≤10%; T(700nm-900nm) ≥45%;

[0217] TA6: Valley transmittance wavelength is 500-650nm; T(350nm-450nm)≤40%; T(485nm-615nm)≥50%; T(800nm-900nm)≥60%;

[0218] TA7: Valley transmittance wavelength is 575-750nm; T(400nm-570nm) ≥45%; T(630nm-730nm) ≤10%; T(775nm-900nm) ≥50%;

[0219] TA8: Valley transmittance wavelength is 600-750nm; T(460nm-565nm)≥40%; T(620nm-745nm)≤10%; T(800nm-900nm)≥45%;

[0220] TA9: Valley transmittance wavelength is 600-760nm; T(460nm-580nm)≥50%; T(635nm-645nm)≤15%; T(800nm-900nm)≥50%.

[0221] Comparing Figures 12 and 8, it can be seen that the combination of regular and inverted square truncated pyramid shapes not only helps to separate the transmittance curves that are partially overlapped outside the preset wavelength range, but also helps to separate the transmittance curves that are partially overlapped within the preset wavelength range, thereby improving the distinction between different spectra and enhancing the effect of spectral modulation.

[0222] Furthermore, by combining regular and inverted square truncated pyramid shapes, the transmittance of the spectral chip within the preset wavelength range is also relatively improved.

[0223] In summary, this structure not only optimizes spectral discrimination but also improves the accuracy of spectral modulation, enabling the spectral chip to perform effective modulation and identification over a wider wavelength range. Through this structural optimization, the overall performance of the spectral chip is enhanced, allowing it to better handle complex spectral signal modulation requirements.

[0224] As mentioned earlier, it is often difficult to form a perfect cube or cuboid structure in the ideal filter unit film layer in the process. There will always be a slight slope. The inventors of this application have taken advantage of this defect and amplified it by deliberately making it into the shape of a regular square truncated pyramid and an inverted square truncated pyramid to form an overlapping area. This is easier to achieve in the process preparation, thereby further improving the preparation accuracy and quality.

[0225] Furthermore, the above examples use 500-650nm as the key wavelength band; however, this application is not limited to this. For example, if considering applications in the ultraviolet spectral imaging field, such as surface defect detection, fluorescence imaging, forensic medicine and security (e.g., bloodstain and fingerprint recognition), and cultural relic identification and restoration, the key wavelength band is between 200-400nm. If considering applications in the infrared spectral imaging field, such as agriculture, food inspection, medical imaging, security monitoring, and material sorting, the key wavelength band is between 800-1700nm. Based on the teachings of this application, the transmittance curves of the corresponding basic material layers can be designed for the corresponding wavelength bands.

[0226] Furthermore, in the existing technology, taking the spectral chip structure disclosed in patent CN113497065A as an example, the filter film includes N periods, each period including T1, T2...Tn units. The specific process method includes: firstly, coating a first type of filter film material on the photoelectric conversion substrate using a standard spraying or spin coating method, then coating an etching layer, retaining the required areas and etching away the unnecessary areas according to the correspondence with the pixels of the photoelectric conversion substrate; then coating a second type of filter film material, then coating another etching layer, retaining the required areas and etching away the unnecessary areas according to the correspondence with the pixels of the photoelectric conversion substrate; repeating this process until all N types of filter film materials are coated onto the photoelectric conversion substrate. After the above N types of filter film materials are coated and etched one by one, a complete filter film with N periods is finally formed.

[0227] In this process, the etching involved in fabricating the subsequent filter film material can easily damage the already fabricated filter film. Furthermore, cleaning is typically required after each etching step, all of which reduce the thickness of the subsequent filter film, preventing it from reaching the preset thickness and thus failing to obtain the desired transmittance profile. Technicians often try to improve this by adjusting various preparation parameters (such as curing time); however, as the number of spectral modulation channels increases, the number of factors requiring coordination grows, eventually becoming impossible to balance simultaneously.

[0228] Therefore, in another embodiment of this application, as shown in FIG2, when preparing the spectral modulation layer of the spectral chip, the spectral chip module further includes: a first protective film layer disposed on the spectral modulation layer, wherein the first protective film layer includes a plurality of sub-protective film layers, and at least two filter sub-units in the same filter unit are covered by the same sub-protective film layer.

[0229] Taking a filter unit comprising 3*3 filter sub-units C1-C9 as an example, where the first row contains C1-C3, the second row contains C4-C6, and the third row contains C7-C9. In this example, the first protective film layer includes three sub-protective film layers: the first sub-protective film layer covers C1-C3, the second sub-protective film layer covers C4-C6, and the third sub-protective film layer covers C7-C9. These three sub-protective film layers together constitute the first protective film layer. In reality, the first, second, and third sub-protective film layers are located in the same layer, but are implemented in different process steps (see the method described later).

[0230] Understandably, in the entire spectral chip, the filter subunits C1-C3 in each periodic unit (filter unit) are fabricated sequentially first, and a first sub-protective film layer is applied to them. Then, C4-C6 in each periodic unit are fabricated, and a second sub-protective film layer is applied to them. Finally, C7-C9 in each periodic unit are fabricated, and a third sub-protective film layer is applied to them. During the fabrication of filter subunits C4-C9, the surface of filter subunits C1-C3 is not damaged, nor is the thickness of filter subunits C1-C3 reduced during the cleaning process. Furthermore, the impact on filter subunits C1-C3 does not need to be considered when setting parameters in subsequent fabrication processes, thus greatly reducing the complexity of parameter setting during chip fabrication. Similarly, after applying the second sub-protective film layer to filter subunits C4-C6, the complexity of parameter setting for fabricating filter subunits C7-C9 is also greatly reduced, while ensuring the integrity and functionality of filter subunits C4-C6. Those skilled in the art will understand that this example is a case of creating line by line. Of course, it is also possible to create from right to left within the same line, for example, creating C3, C2, and C1 sequentially in the first line.

[0231] In another alternative embodiment, the filters can be fabricated column by column. That is, filter sub-units C1, C4, and C7 are fabricated sequentially, and a first sub-protective film layer is placed on them; then C2, C5, and C8 are fabricated sequentially, and a second sub-protective film layer is placed on them; finally, C3, C7, and C9 are fabricated, and a third sub-protective film layer is placed on them.

[0232] The two embodiments above are examples of sequential fabrication of filter sub-units. In another alternative embodiment, the filter sub-units are fabricated in the following order: the even-numbered filter sub-units are fabricated first, followed by the odd-numbered filter sub-units, where odd and even numbers are calculated from row 1, column 1 to row 3, column 3. For example, C2, C4, C6, and C8 are fabricated first, and a first sub-protective film is placed on them; then C1, C3, C5, C7, and C9 are fabricated, and a second sub-protective film is placed on them. Alternatively, the odd-numbered filter sub-units are fabricated first, followed by the even-numbered filter sub-units. In this case, the first sub-protective film is placed on C1, C3, C5, C7, and C9, and the second sub-protective film is placed on C2, C4, C6, and C8. This approach can be applied to the structure shown in Figure 10 described earlier.

[0233] In the above example, each filter unit is a 3*3 array structure. However, it is not limited to this. It can also be a 4*4, 5*5, or even an M*N array structure.

[0234] In one embodiment, the spectral chip filter unit is a 4*4 array structure, with the first sub-protective film layer disposed on filter sub-units C1-C4, the second sub-protective film layer disposed on filter sub-units C5-C8, the third sub-protective film disposed on C9-C12, and the fourth sub-protective film disposed on C13-C16.

[0235] In one embodiment, the spectral chip filter unit is a 5*5 array structure, with the first sub-protective film layer disposed on filter sub-units C1-C5, the second sub-protective film layer disposed on filter sub-units C6-C10, the third sub-protective film disposed on C11-C15, the fourth sub-protective film disposed on C16-C20, and the fifth sub-protective film disposed on C21-C25.

[0236] In the example where the filter unit consists of M rows and N columns of filter sub-units, the first protective film layer includes M sub-protective film layers, where the m-th sub-protective film layer covers the m-th row and N filter sub-units, where m traverses from 1 to M, and M and N are both natural numbers greater than or equal to 2.

[0237] In another example where the filter unit consists of M rows and N columns of filter sub-units, the first protective film layer includes N sub-protective film layers, where the nth sub-protective film layer covers the M filter sub-units in the nth column, where n ranges from 1 to N, and M and N are both natural numbers greater than or equal to 2.

[0238] In another example where a filter unit consists of M rows and N columns of filter sub-units, the first protective film layer includes a first sub-protective film layer and a second sub-protective film layer, wherein the first sub-protective film layer covers the even-numbered filter sub-units and the second sub-protective film layer covers the odd-numbered filter sub-units, wherein the odd and even numbers are calculated from the first row and first column to the M-th row and N-th column.

[0239] By setting up protective films, it is possible to effectively ensure that each filter unit will not interfere with each other after it is fabricated, making the performance of the spectral chip more stable and ideal.

[0240] More broadly, those skilled in the art, guided by the above teachings, can achieve the aforementioned technical effects by fabricating two or more filter sub-units (whether adjacent or spaced apart) and then adding a sub-protective film layer during the fabrication process. Alternatively, a sub-protective film layer can be added after fabricating a single filter sub-unit, although this increases the complexity and cost of the process; in actual fabrication, both the process and the protective effect must be considered.

[0241] In this application, the material of the protective film is not limited, as long as it can achieve high transmittance within the wavelength range of interest in the application. In other words, within this wavelength range, the transmittance of the protective film can be regarded as a straight line, for example, a transmittance of more than 95%.

[0242] Those skilled in the art will understand that the thickness of the protective film layer has a significant impact on the transmitted light intensity. If the protective film layer is too thick, the incident light will not achieve the desired intensity after passing through the spectral modulation layer; if the protective film layer is too thin, it will not provide any protective effect. Based on experimental data, the inventors have determined that a thickness range of 10-500 nm for the first protective film layer is optimal.

[0243] In one embodiment, the spectral chip module may further include a second protective film layer (not shown in the figure), which is disposed between the photoelectric sensing layer and the base material layer. The thickness and material of the second protective film layer may be the same as those of the first protective film layer.

[0244] It is understandable that the aforementioned base material layer, while possessing light modulation capabilities, also serves to ensure the integrity of the photoelectric sensing layer during the fabrication of the spectral chip. Therefore, in one embodiment, if the spectral chip has a base material layer, a second protective film layer may not be necessary.

[0245] Furthermore, spectroscopic cameras often rely on the collaborative work of a spectral chip and a filter (such as a bandpass filter) to ensure that the camera can acquire incident light within the desired wavelength range, meeting the functional and performance requirements of the spectroscopic camera in various application scenarios. However, in existing technologies, whether it is a filter-based spectroscopic camera (as shown in Figure 13(a)) or a filter-coated spectroscopic camera (as shown in Figure 13(b)), traditional spectroscopic cameras typically place the filter (or coating) on ​​the lens, with a distance between it and the spectral modulation layer of the spectral chip. This design makes the filter susceptible to the influence of external environmental factors (such as temperature and humidity), resulting in aging and affecting the quality of the spectral image. Moreover, since the filter is fixed to the housing, its stability is poor, making it susceptible to vibration, which also affects the quality of the spectral image. In addition, to ensure precise alignment between the optical system and the spectral chip, the physical centers of the lens, filter, and spectral chip of the spectroscopic camera must be on the same straight line, and the lens must focus the light from the target scene onto the spectral modulation layer of the spectral chip. Therefore, this design method has relatively complex compatibility.

[0246] Therefore, as shown in FIG2, in one embodiment, the spectral camera further includes a filter structure disposed on the first protective film layer.

[0247] In one example, the filtering structure is a light filter, mainly made of materials such as glass, plastic, or optical film. The light filter not only serves to filter light but also protects the integrity of the spectral modulation layer during fabrication, thus making the performance of the spectral camera more stable.

[0248] In one example, the thickness of the filter is 0.05mm-0.5mm.

[0249] Therefore, in one example, as shown in Figure 14, the spectral chip module also includes:

[0250] The circuit board, on which the spectral chip is mounted and electrically connected, contains the spectral chip.

[0251] A support is disposed on the circuit board, and the filter is bonded to the spectral modulation layer by means of the support.

[0252] In one example, the bandpass filter structure may also be a coating made of an oxide, a fluoride, or a mixture of both.

[0253] In one example, the filter coating is deposited on the surface of the microlens facing the silicon substrate or on the surface of the first protective film layer facing the microlens.

[0254] In one example, when the filter coating is disposed on the surface of the first protective film layer facing the microlens, the spectral chip module further includes a third protective film layer disposed between the filter coating and the microlens layer, wherein the thickness and material of the third protective film layer may be the same as those of the first protective film layer.

[0255] In one example, the filter structure is a bandpass filter structure with a lower cutoff wavelength of 350 nm and an upper cutoff wavelength of 950 nm.

[0256] In one example, the spectral chip module further includes a computing unit (not shown in the figure) and an interface unit, which are electrically connected to the spectral chip through module packaging process and circuit board, and then electrically connected to the spectral chip. The computing unit is used to receive electrical signals from the spectral sensing layer and invert the electrical signals into a color image.

[0257] The interface unit includes an input interface and an output interface, wherein the input interface is used to provide power to drive the spectral camera, and the output interface is used to connect to an output device.

[0258] In one example, the computing unit is mounted on the circuit board.

[0259] When the spectral chip module is installed inside the housing and assembled with the optical system to form a spectral camera as shown in the figure, this application sets the filter structure together with the spectral chip (whether through coating or bonding), avoiding direct contact between the filter and the external environment, and avoiding factors such as temperature, humidity, and vibration. This reduces performance fluctuations caused by external environmental factors, thus ensuring the performance stability of the filter. At the same time, the design of the encapsulated filter structure simplifies the optical path and reduces the necessity of complex connections between the filter structure and the lens, optimizing the efficiency and performance of the overall optical system.

[0260] A second aspect of this application provides a method for preparing the above-mentioned spectral chip module.

[0261] In one embodiment, the method includes forming a base material layer and a spectral modulation layer on a silicon substrate including a photoelectric sensing layer, specifically including:

[0262] A base material is formed on the photoelectric sensing layer;

[0263] The first filter sub-unit material of each filter unit is formed on the base material;

[0264] The first filter subunit material is patterned, wherein the patterned first filter subunit is cuboid, and during this process, the base material except for the base material at the position of the first filter subunit to be formed is cleaned and thinned to a first preset thickness.

[0265] The i+1th filter unit material in each filter unit is formed on the patterned i-th filter unit material and the thinned base material;

[0266] The material of the (i+1)th filter subunit is patterned, wherein the patterned (i+1)th filter subunit is a cuboid, and during this process, the base material other than the base material at the position of the (i+1)th filter subunit to be formed and the base material at the positions of the first to the i-th filter subunits that have been formed is cleaned and thinned to the (i+1)th preset thickness, wherein the (i+1)th filter subunit is adjacent to the i-th filter subunit, i traverses from 1 to n, and n is the total number of filter subunits included in each filter unit.

[0267] Optionally, in the entire spectral chip, the sum of the thickness of each filter subunit and the thickness of its corresponding base material in the projection relationship is equal; and in the same filter unit, the thickness of the base material corresponding to different filter subunits is stepped, with the thickness of the base material corresponding to the filter subunits fabricated earlier being larger.

[0268] Optionally, before forming a base material layer on the photoelectric sensing layer, the method further includes:

[0269] A dielectric material is formed on the photoelectric sensing layer;

[0270] The medium material is patterned to form a grid structure, wherein the orthographic projection of each mesh of the grid structure onto the photoelectric sensing layer is aligned with the orthographic projection of one or more filter sub-units to be formed onto the photoelectric sensing layer.

[0271] Optionally, the base material in each mesh of the mesh structure corresponds to a filter sub-unit, wherein the sum of the thicknesses of the base materials in all meshes and their corresponding filter sub-units is equal throughout the entire spectral chip; and within the same filter unit, the thicknesses of the base materials corresponding to different filter sub-units are stepped, with the base material corresponding to the filter sub-units fabricated earlier having a larger thickness.

[0272] One embodiment of this application provides a method for forming at least one inclined overlap region relative to a silicon substrate between each of the above-described filter subunits and adjacent filter subunits, specifically including:

[0273] The first filter sub-unit material of each filter unit is formed on the photoelectric sensing layer;

[0274] The material of the first filter subunit is patterned, wherein the patterned first filter subunit is in the shape of a regular frustum;

[0275] The j-th filter unit material in each filter unit is formed on the patterned i-th filter unit material and the exposed area;

[0276] The material of the j-th filter sub-unit is patterned, wherein the patterned j-th filter sub-unit is a regular frustum shape, wherein i and j traverse from 1 to n and the i-th filter sub-unit and the j-th filter sub-unit are not adjacent in physical space, and n is the total number of filter sub-units included in each filter unit.

[0277] The areas exposed outside the regions forming all the frustum-shaped filter sub-units are filled with the remaining filter sub-unit material to form each filter sub-unit. Each filter sub-unit includes multiple filter sub-units with different transmittance curves, and there is at least one inclined overlap area between each filter sub-unit and its adjacent filter sub-units. The orthographic projection of the inclined overlap area on the silicon substrate spans two adjacent pixels.

[0278] In one example, each filter unit includes 3*3 filter subunits C1-C9, wherein the first row along the first direction consists of C1-C3, the second row along the first direction consists of C4-C6, and the third row along the first direction consists of C7-C9. C2, C4, C6, and C8 are regular frustums, and C1, C3, C5, C7, and C9 are inverted frustums.

[0279] In the method, C2, C4, C6 and C8 are prepared first, and then C1, C3, C5, C7 and C9 are filled.

[0280] In one embodiment, a method for preparing a spectral modulation layer and a first protective film is provided, wherein the spectral modulation layer and the first protective layer are formed alternately.

[0281] In one example, the filtering unit consists of M rows and N columns of filtering sub-units.

[0282] The first protective film layer includes M sub-protective film layers, where the m-th sub-protective film layer covers the N filter sub-units in the m-th row, where m traverses from 1 to M, and M and N are both natural numbers greater than or equal to 2.

[0283] In another specific example, the filter unit consists of M rows and N columns of filter sub-units.

[0284] The first protective film layer includes N sub-protective film layers, where the nth sub-protective film layer covers the M filter sub-units in the nth column, where n traverses from 1 to N, and M and N are both natural numbers greater than or equal to 2.

[0285] In yet another specific example, the filter unit consists of M rows and N columns of filter sub-units.

[0286] The first protective film layer includes a first sub-protective film layer and a second sub-protective film layer, wherein the first sub-protective film layer covers the even-numbered filter sub-units, and the second sub-protective film layer covers the odd-numbered filter sub-units, wherein the odd and even numbers are calculated from the first row and first column to the M-th row and N-th column.

[0287] Next, we will use the structure shown in Figure 1 as an example for specific explanation. In the structure shown in Figure 1, the filter unit includes 3*3 filter subunits C1-C9, where the first row along the first direction (from left to right) consists of C1-C3, the second row along the first direction consists of C4-C6, and the third row along the first direction consists of C7-C9.

[0288] The spectral modulation layer and the first protective layer are alternately formed, including:

[0289] S100. C1-C3 of each filter unit are sequentially formed on the photoelectric sensing layer, as shown in Figure 15. For specific process methods of forming the filter sub-units, please refer to CN113497065A;

[0290] S101, Form the first sub-protective film material layer.

[0291] S102. Pattern the first sub-protective film material layer to obtain the first sub-protective film layer, which only covers C1-C3, as shown in Figure 16.

[0292] S103. C4-C6 of each filter unit are sequentially formed on the photoelectric sensing layer, as shown in Figure 17.

[0293] S104, Forming the second sub-protective film material layer;

[0294] S105. Pattern the second sub-protective film material layer to obtain the second sub-protective film layer, which only covers C4-C6, as shown in Figure 18.

[0295] S106. C7-C9 of each filter unit are sequentially formed on the photoelectric sensing layer, as shown in Figure 19;

[0296] S107, Forming the third sub-protective film material layer;

[0297] S108. Pattern the third sub-protective film material layer to obtain the third sub-protective film layer, which only covers C7-C9, as shown in Figure 20.

[0298] In another embodiment, taking the structure shown in Figure 1 as an example, the filter unit includes 3*3 filter sub-units C1-C9, where the first row along the first direction contains C1-C3, the second row along the first direction contains C4-C6, and the third row along the first direction contains C7-C9.

[0299] The spectral modulation layer and the first protective layer are alternately formed, including:

[0300] C1, C4 and C7 of each filter unit are sequentially formed on the photoelectric sensing layer;

[0301] Forming the first sub-protective film material layer;

[0302] Pattern the first sub-protective film material layer to obtain the first sub-protective film layer, which only covers C1, C4 and C7;

[0303] C2, C5 and C8 of each filter unit are sequentially formed on the photoelectric sensing layer;

[0304] Forming a second protective film material layer;

[0305] The second sub-protective film material layer is patterned to obtain the second sub-protective film layer, which only covers C2, C5 and C8;

[0306] C3, C6 and C9 of each filter unit are sequentially formed on the photoelectric sensing layer;

[0307] Forming a third protective film material layer;

[0308] The third sub-protective film material layer is patterned to obtain a third sub-protective film layer that only covers C3, C6 and C9.

[0309] In another embodiment, still taking the structure shown in Figure 1 as an example, the filter unit includes 3*3 filter sub-units C1-C9, wherein the first row along the first direction consists of C1-C3, the second row along the first direction consists of C4-C6, and the third row along the first direction consists of C7-C9.

[0310] The spectral modulation layer and the first protective layer are alternately formed, including:

[0311] C2, C4, C6 and C8 of each filter unit are sequentially formed on the photoelectric sensing layer;

[0312] Forming the first sub-protective film material layer;

[0313] Patterning the first sub-protective film material layer yields the first sub-protective film layer, which only covers C2, C4, C6, and C8;

[0314] C1, C3, C5, C7 and C9 of each filter unit are sequentially formed on the photoelectric sensing layer;

[0315] Forming a second protective film material layer;

[0316] The second sub-protective film material layer is patterned to obtain the second sub-protective film layer, which only covers C1, C3, C5, C7 and C9.

[0317] In a preferred embodiment, the method further includes forming a second protective film layer between the photoelectric sensing layer and the base material layer.

[0318] In one embodiment, the method further includes: forming a microlens layer on the filter structure, wherein the microlens layer includes a microlens array consisting of a plurality of microlenses, wherein the orthogonal projection of each microlens on the silicon substrate is aligned with the orthogonal projection of one of the plurality of filter subunits on the silicon substrate.

[0319] In one embodiment, the method further includes: assembling a computing unit and an interface unit in a spectral chip module, wherein the incident optical signal is modulated by a spectral modulation layer and then enters a photoelectric sensing layer, the photoelectric sensing layer converts the incident optical signal modulated by the spectral modulation material layer into an electrical signal, the computing unit processes and analyzes the electrical signal, and inverts a color image based on the electrical signal; the interface unit includes an input interface and an output interface, wherein the input interface is used to provide power to drive the spectral camera, and the output interface is used to connect an output device.

[0320] The above description has been given for illustrative and descriptive purposes. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, additions, and sub-combinations therein.

[0321] It should be noted that although the steps in the above embodiments are described in a specific order, those skilled in the art will understand that in order to achieve the effect of this application, different steps do not necessarily have to be executed in such an order. They can be executed simultaneously (in parallel) or in other orders, and these variations are all within the scope of protection of this application.

[0322] The technical solutions of this application have been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of this application.

Claims

1. A spectroscopic camera, characterized in that, include: A housing with an opening; a spectral chip module located inside the housing; A lens assembly, fixed to the housing through the opening, focuses incident light onto the spectral chip module; wherein the spectral chip module includes: a spectral chip, wherein the spectral chip includes: a silicon substrate including a photoelectric sensing layer, wherein the photoelectric sensing layer includes multiple pixels; a base material layer disposed on the photoelectric sensing layer; and a spectral modulation layer disposed on the base material layer, wherein the spectral modulation layer includes multiple filter units arranged in an array, each filter unit including multiple filter sub-units, and each filter sub-unit having a different transmittance curve; wherein the light incident on the spectral chip is modulated by the spectral modulation layer and the base material layer.

2. The spectral camera according to claim 1, characterized in that, The base material layer has a first transmittance curve, wherein the shape of the first transmittance curve is designed such that the transmittance curve of the light incident on the spectral chip after being modulated by the spectral modulation material layer and the base material layer is more sensitive in a preset wavelength range than in a response outside the preset wavelength range.

3. The spectral camera according to claim 2, characterized in that, The first transmittance curve has a higher transmittance within a preset wavelength range than the transmittance outside the preset wavelength range.

4. The spectral camera according to claim 1, characterized in that, The spectral chip further includes a first protective film layer disposed on the spectral modulation layer, wherein the first protective film layer includes multiple sub-protective film layers, and at least two filter sub-units in the same filter unit are covered by the same sub-protective film layer.

5. The spectral camera according to claim 1, characterized in that, At least two adjacent filter sub-units within the same filter unit are covered by the same sub-protective film layer.

6. The spectral camera according to claim 1, characterized in that, At least two non-adjacent filter sub-units within the same filter unit are covered by the same sub-protective film layer.

7. The spectroscopic camera according to claim 4, characterized in that, The spectral camera further includes a filter structure disposed on the first protective film layer.

8. The spectroscopic camera according to claim 7, characterized in that, The filtering structure is a filter or a filter coating.

9. The spectroscopic camera according to claim 7, characterized in that, The spectral chip module further includes a microlens layer disposed on the filter structure, comprising a microlens array composed of multiple microlenses, wherein the orthographic projection of each microlens on the silicon substrate is aligned with the orthographic projection of one of the multiple filter subunits on the silicon substrate.

10. The spectral camera according to claim 1, characterized in that, The spectral camera further includes a computing unit and an interface unit. The computing unit is used to receive electrical signals from the spectral sensing layer and invert them into a color image based on the electrical signals. The interface unit includes an input interface and an output interface, wherein the input interface is used to provide power to drive the spectral camera, and the output interface is used to connect to an output device.

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