Spectroscopic image sensor and system and method of fabricating a pixelated liquid crystal device

Abstract

The application provides a spectral image sensor and system and a preparation method of a pixelated liquid crystal device, the spectral image sensor comprises: an image detection array and a spectral filter array, the image detection array and the spectral filter array are arranged in a stack, the spectral filter array comprises a pair of polarizers and a pixelated liquid crystal device arranged between the pair of polarizers, and liquid crystals in each pixel region of the pixelated liquid crystal device have a fixed out-of-plane rotation angle. The spectral image sensor and system and the preparation method of the pixelated liquid crystal device provided by the embodiment of the application have simple and stable pixelated liquid crystal device structures, and the cost of the spectral image sensor is reduced.

Description

Technical Field

[0001] This invention relates to the field of spectral imaging technology, specifically to a spectral image sensor and system, and a method for fabricating a pixelated liquid crystal device. Background Technology

[0002] Snapshot spectral imaging is an advanced optical imaging technology that can acquire two-dimensional spatial information and one-dimensional continuous spectral information of a target scene, and directly generate a three-dimensional data cube containing spatial coordinates and spectral dimensions. With the continuous advancement of related computing architectures and the continuous optimization of reconstruction algorithms, snapshot spectral imaging technology is gradually penetrating and transforming into diverse application scenarios such as industrial inspection, biomedicine, environmental monitoring and precision agriculture.

[0003] Snapshot spectral imaging commonly uses photoelectric detectors such as CCD and CMOS. These detectors convert light signals into electrical signals, which are then processed through signal preprocessing and digitization to form spectral image data. Spectral image detection arrays typically include an image detection array and a spectral filtering array. Spectral filtering arrays require custom-designed pixel-level heterogeneous filters, which are complex in structure, difficult to manufacture, and expensive, limiting the application and widespread use of snapshot spectral imaging. Summary of the Invention

[0004] To address the problems in the prior art, embodiments of the present invention provide a spectral image sensor and system, as well as a method for fabricating a pixelated liquid crystal device, which can at least partially solve the problems existing in the prior art.

[0005] In a first aspect, the present invention proposes a spectral image sensor, comprising an image detection array and a spectral filtering array, wherein the image detection array and the spectral filtering array are stacked together, and the spectral filtering array comprises a pair of polarizers and a pixelated liquid crystal device sandwiched between the pair of polarizers, wherein the liquid crystal in each pixel region of the pixelated liquid crystal device has a fixed out-of-plane rotation angle.

[0006] Furthermore, the transmission axes of the two polarizers in the pair of polarizers are arranged at an arbitrary angle.

[0007] Furthermore, the liquid crystal orientation of each pixel region in the pixelated liquid crystal device is a parallel orientation mode, and the liquid crystal orientation is neither parallel nor perpendicular to the light transmission axis of either of the pair of polarizers. The out-of-plane rotation angle of the liquid crystal in each pixel region is fixed to an arbitrary angle that is not exactly the same.

[0008] Secondly, the present invention proposes a snapshot spectral imaging system, comprising the spectral image sensor, imaging lens, and data processing module described in any of the above embodiments, wherein: The imaging lens is used to map the target scene onto the spectral image sensor; The spectral image sensor is used for spectral image modulation and detection to obtain the acquired signal; The data processing module is used to perform signal processing on the acquired signals.

[0009] Thirdly, the present invention provides a method for fabricating a pixelated liquid crystal device, comprising: A liquid crystal device is obtained by filling a standard liquid crystal cell with a mixed crystal; wherein the mixed crystal includes a reactive liquid crystal monomer, the mixed crystal includes a reactive liquid crystal monomer and a conventional nematic liquid crystal, the mixed crystal includes a reactive liquid crystal monomer and a photoinitiator, or the mixed crystal includes a conventional nematic liquid crystal, a reactive liquid crystal monomer and a photoinitiator. The liquid crystal device is driven by power and then pixelated by ultraviolet exposure curing to obtain a pixelated liquid crystal device.

[0010] Furthermore, the mass fraction of the reactive liquid crystal monomer in the mixed crystal is greater than or equal to 80% and less than 100%, and the mass fraction of the photoinitiator is greater than 0 and less than or equal to 20%.

[0011] Furthermore, the mass fraction of the reactive liquid crystal monomer in the mixed crystal is greater than or equal to 1% and less than 100%, and the mass fraction of the ordinary nematic liquid crystal is greater than or equal to 0 and less than or equal to 99%.

[0012] Furthermore, in the mixed crystal, the mass fraction of the ordinary nematic liquid crystal is greater than 0 and less than 99%, the mass fraction of the reactive liquid crystal monomer is greater than 1% and less than 100%, and the mass fraction of the photoinitiator is greater than 0 and less than or equal to 20%.

[0013] Furthermore, the ordinary nematic liquid crystal is an E7 liquid crystal, a 5CB liquid crystal, or an MLC-2065 liquid crystal.

[0014] Furthermore, the reactive liquid crystal monomer is RM257, RM82 or RM23.

[0015] Furthermore, the photoinitiator is either Irgacure 651 or Irgacure 184.

[0016] The spectral image sensor and system and the method for fabricating a pixelated liquid crystal device provided in this invention include an image detection array and a spectral filtering array, wherein the image detection array and the spectral filtering array are stacked. The spectral filtering array includes a pair of polarizers and a pixelated liquid crystal device sandwiched between the pair of polarizers. The liquid crystal in each pixel region of the pixelated liquid crystal device has a fixed out-of-plane rotation angle. The pixelated liquid crystal device can be realized by using polarizers and ordinary liquid crystal cells. The pixelated liquid crystal device has a simple and stable structure, which reduces the cost of the spectral image sensor. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This is a schematic diagram of the principle of a snapshot spectral imaging system provided in an embodiment of the present invention.

[0018] Figure 2 This is a cross-sectional structural diagram of a spectral image sensor provided in an embodiment of the present invention.

[0019] Figure 3 This is a top view schematic diagram of the spectral filtering array provided in an embodiment of the present invention.

[0020] Figure 4 This is a simulation result of the spectral filtering principle of a pixelated liquid crystal device provided in an embodiment of the present invention.

[0021] Figure 5 This is a schematic diagram of the structure of a snapshot spectral imaging system provided in an embodiment of the present invention.

[0022] Figure 6 This is a schematic flowchart of a method for fabricating a pixelated liquid crystal device according to an embodiment of the present invention.

[0023] Figure 7 This is a schematic diagram of the spectral filtering characteristic curve of a spectral filtering array provided in an embodiment of the present invention.

[0024] Figure 8 This is a correlation matrix diagram between the spatial transmittance of 31 wavelength channels provided in an embodiment of the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Here, the illustrative embodiments and their descriptions are used to explain the present invention, but are not intended to limit the present invention. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. The acquisition, storage, use, and processing of data in the technical solutions of this application all comply with relevant laws and regulations. The user information in the embodiments of this application is obtained through legal and compliant means, and the acquisition, storage, use, and processing of user information have been authorized and agreed upon by the customer.

[0026] To facilitate understanding of the technical solution provided in this application, the relevant content of the technical solution in this application will be explained below.

[0027] Figure 1 This is a schematic diagram illustrating the principle of snapshot spectral imaging according to an embodiment of the present invention, as shown below. Figure 1 As shown, the imaging lens maps the spatial information of the target onto the imaging plane, the spectral filtering array at the imaging plane performs spatial-spectral joint encoding on the spectral image, and then the image detection array performs snapshot detection to obtain the acquired signal, which is then sent to the image signal processor for processing.

[0028] A pixel-aligned spectral filter array is mounted in front of the detection pixel array. The imaging lens is responsible for mapping the target scene information onto the imaging plane. The spectral filter array at the imaging plane performs spatial-spectral joint encoding on the spectral image. That is, by designing the transmittance characteristics of the spectral filter array, specific transmittance is achieved at different spatial pixel positions and different wavelength channels, enabling highly efficient spatial-spectral encoding. Subsequently, the image detection array performs snapshot detection to obtain the acquired signal, and sends the acquired signal to the image signal processing unit for processing. By integrating a spectral filter array in front of the image detection array, snapshot-style acquisition of spectral image information of the target scene is achieved.

[0029] Imaging lenses are used to map target scene information onto the imaging plane. Imaging lenses need to have good aberration correction, a high optical transfer function, and a spectral passband that matches the target wavelength to ensure that target scene information, especially spatial-spectral details, can be clearly and faithfully transmitted to subsequent stages. The continuous spectral radiation signal reflected or emitted by the target, after passing through the lens, forms a specific spatial intensity distribution on the imaging plane, which is the intermediate image in the traditional sense.

[0030] The spectral encoding process occurs within the spectral filtering array. This array is aligned microscopically with the pixels of the image detection array. Each filtering unit in the array corresponds to one or more detector pixels, forming the basic unit of spatial-spectral joint modulation. When the light signal from the intermediate image passes through the spectral filtering array, the broadband information at each spatial point is selectively transmitted by its corresponding filtering unit, allowing only light intensity within a specific wavelength range to pass. This process essentially completes the spatial spectral encoding of the three-dimensional spectral data cube (two-dimensional space, one-dimensional spectrum), that is, encoding the wavelength information at different spatial locations with distinct features and representing it as a spatial intensity information distribution on the detection plane.

[0031] This application proposes an innovative structural scheme for a spectral filtering array, namely a novel pixelated spectral filtering array based on liquid crystals. The pixelated liquid crystal device, by incorporating a liquid crystal polymer, enables simultaneous exposure and curing of the liquid crystal under electrical drive, thereby fixing the liquid crystal in a specific rotational state without the need for an electric field. Therefore, a pixelated liquid crystal phase sheet can be realized, possessing birefringent crystal characteristics (polarization selectivity in modulation), and the specific phase modulation value of each pixel region varies depending on the angle and operating wavelength. Thus, by sandwiching the pixelated liquid crystal device between polarizers, the pixelated phase modulation of wavelength dispersion can be transformed into wavelength-sensitive pixelated amplitude changes, resulting in a spectral filtering array that adapts to complex variations in both wavelength and space, thereby achieving high-efficiency spectral image encoding. The pixelated liquid crystal device can be fabricated using polarizers and standard liquid crystal cells, resulting in low cost.

[0032] The spectrally encoded two-dimensional light intensity distribution is received by the adjacent image detection array. The image detection array simultaneously records the light intensity signals of all spatially encoded points within the entire field of view, achieving snapshot-like acquisition. The final raw image is not an intuitive natural image, but an encoded image composed of mosaics of information from different spectral channels, where the grayscale value of each pixel represents the radiance of the corresponding spatial point of the target under a specific spectral signal.

[0033] Figure 2 This is a schematic cross-sectional view of a spectral image sensor provided in an embodiment of the present invention, as shown below. Figure 2 The spectral image sensor provided in this embodiment of the invention includes an image detection array 1 and a spectral filtering array 2. The image detection array 2 and the spectral filtering array 2 are stacked. The spectral filtering array 2 includes a pair of polarizers and a pixelated liquid crystal device 201 sandwiched between the pair of polarizers. The liquid crystal in each pixel region of the pixelated liquid crystal device 201 has a fixed out-of-plane rotation angle.

[0034] Specifically, the image detection array 1 is integrated on its surface. The target scene is mapped onto the imaging plane through the imaging lens, and the image detection array 1 at the imaging plane performs spatial-spectral joint encoding on the spectral image. The spectral image is then captured by the image detection array 1 after passing through the spectral filtering array 2. The spectral filtering array 2 is pixel-aligned with the image detection array 1.

[0035] The spectral filter array 2 includes a first polarizer 202, a pixelated liquid crystal device 201, and a second polarizer 203 arranged sequentially. The rotation angle of each pixel in the pixelated liquid crystal device 201 is fixed, thus fixing the liquid crystal in a specific rotational state without the need for an electric field. By sandwiching the pixelated liquid crystal device 201 between the first polarizer 202 and the second polarizer 203, pixelated phase modulation of wavelength dispersion can be converted into wavelength-sensitive pixelated amplitude changes, resulting in a spectral filter array 2 that varies with both wavelength and space, thereby achieving high-efficiency spectral image encoding.

[0036] The pixelated liquid crystal device 201 includes a first glass cover plate 201-1, a pixelated liquid crystal layer 201-2, and a second glass cover plate 201-3 stacked together, with the pixelated liquid crystal layer 201-2 disposed between the first glass cover plate 201-1 and the second glass cover plate 201-3. The spectral curve within each pixel range of the pixelated liquid crystal layer 201-2 is controlled by a single variable—the out-of-plane rotation angle of the liquid crystal—making it easy to optimize and control. The angle θ between the long axis rotation plane of the liquid crystal in the pixelated liquid crystal device 201 and the transmission axis of the incident polarizer is θ. The angle θ is used to balance broadband transmittance and modulation peak-valley range. The rotation angle within each pixel range of the pixelated liquid crystal device 201 controls the propagation phase value δ, while the phase modulation amount also changes with wavelength. The incident polarizer is the polarizer that first incident light in a pair of polarizers, and it is also the polarizer closer to the imaging lens.

[0037] The spectral image sensor provided in this embodiment of the invention includes an image detection array and a spectral filtering array, wherein the image detection array and the spectral filtering array are stacked. The spectral filtering array includes a pair of polarizers and a pixelated liquid crystal device sandwiched between the pair of polarizers. The liquid crystal in each pixel region of the pixelated liquid crystal device has a fixed out-of-plane rotation angle. The pixelated liquid crystal device can be realized by using polarizers and ordinary liquid crystal cells. The pixelated liquid crystal device has a simple and stable structure, which reduces the cost of the spectral image sensor.

[0038] Based on the above embodiments, further, the transmission axes of the two polarizers in the pair of polarizers are arranged at an arbitrary angle.

[0039] Specifically, the transmission axes of the first polarizer 202 and the second polarizer 203 are arranged at any angle, and the direction lines of the two transmission axes intersect at a certain angle in space, which can be 90° or not, such as 30°, 45°, 60°, 120°, etc. The angle at which the direction lines of the two transmission axes intersect is set according to actual needs, and this embodiment of the invention does not limit it.

[0040] For example, such as Figure 3As shown in the figure, the two dashed arrows represent the transmission axes of the first and second polarizers. The transmission axes of the first and second polarizers are perpendicular. The pixelated liquid crystal device between the first and second polarizers includes a pixelated liquid crystal layer with multiple pixel regions, each with a different liquid crystal rotation angle. The first polarizer can be a polarizer, and the second polarizer can be an analyzer.

[0041] Based on the above embodiments, the liquid crystal orientation of each pixel region in the pixelated liquid crystal device 201 is a parallel orientation mode. The liquid crystal orientation is not parallel and not perpendicular to the light transmission axis of either of the pair of polarizers. The out-of-plane rotation angle (pointing to the pole angle) of the liquid crystal in each pixel region is fixed to an arbitrary angle that is not exactly the same.

[0042] For example, the external rotation angle of the liquid crystal surface of each pixel area can be any angle between 0° and 90°, such as 45°.

[0043] In this embodiment of the invention, the pixel result of the spectral filtering of the pixelated liquid crystal device 201 is as follows: Figure 3 As shown, the pixelated liquid crystal device 201 includes a pixelated liquid crystal layer with a fixed out-of-plane rotation angle. The out-of-plane rotation angles of adjacent pixel regions of the pixelated liquid crystal layer can be different. The area size of each pixel region is on the micrometer scale, and the size of the pixels included in each pixel region is on the nanometer scale. The pixelated liquid crystal layer is a pixelated and solidified liquid crystal layer. The angle between the long axis rotation plane of the liquid crystal and the transmission axis of the incident polarizer is θ. The angle θ is used to balance broadband transmittance and modulation peak-valley range. The rotation angle within each pixel range controls the propagation phase value δ, and the phase modulation amount also varies with wavelength.

[0044] The Jones matrix of the pixelated liquid crystal device 201 is as follows:

[0045] The obtained electric field transmittance is: jE y0 sin(2θ)sin( ).

[0046] Among them, E x0 E represents the polarization component along the x-axis. y0 This represents the polarization component along the y-axis. This indicates that the phase delay caused by the liquid crystal depends on the rotation angle of the liquid crystal.

[0047] It is evident that the angle θ between the long axis rotation plane of the liquid crystal and the upper polarizer affects the amplitude coefficient of the wave function; when θ = 45°, the amplitude coefficient reaches a maximum of 1. The main wave function is affected by the phase modulation amount δ, and the phase value... It varies continuously with wavelength, causing oscillations in the wavelength dimension.

[0048] Simulation results of the spectral filtering principle of the pixelated liquid crystal device 201, such as... Figure 4 As shown, the horizontal axis represents wavelength, and the vertical axis represents… This represents the average rotation angle of the liquid crystal molecules.

[0049] Figure 5 This is a schematic diagram of the structure of a snapshot spectral imaging system provided in an embodiment of the present invention, as shown below. Figure 5 As shown, the snapshot spectral imaging system provided in this embodiment of the invention includes the spectral image sensor 501, imaging lens 502, and data processing module 503 described in any of the above embodiments, wherein: Imaging lens 502 is used to map the target scene onto the spectral image sensor; The spectral image sensor 501 is used for spectral image modulation and detection to obtain the acquired signal; The data processing module 503 is used to perform signal processing on the acquired signals.

[0050] Specifically, the target scene is collected by the imaging lens 502 and mapped onto the spectral image sensor 501. The spectral image is modulated and detected by the spectral image sensor 501 to obtain the acquired signal. The acquired signal is then transmitted to the data processing module 503 for image signal processing and spectral image calculation. The data processing module 503 may include an image processor and a computing unit. The image processor is used to perform image signal processing on the acquired signal, and the computing unit is used to perform spectral image calculation based on the image signal processed data.

[0051] The snapshot spectral imaging system provided in this invention includes a spectral image sensor, an imaging lens, and a data processing module. The imaging lens is used to map a target scene onto the spectral image sensor. The spectral image sensor is used to perform spectral image modulation and detection to obtain a collected signal. The data processing module is used to perform signal processing on the collected signal. Due to the use of the spectral image sensor of this application, high-efficiency spectral image encoding is achieved.

[0052] Figure 6 This is a schematic flowchart of a method for fabricating a pixelated liquid crystal device according to an embodiment of the present invention, as shown below. Figure 6 As shown, the method for fabricating a pixelated liquid crystal device provided in this embodiment of the invention includes: S601. A liquid crystal device is obtained by filling a standard liquid crystal cell with a mixed crystal; wherein the mixed crystal includes a reactive liquid crystal monomer, the mixed crystal includes a reactive liquid crystal monomer and a conventional nematic liquid crystal, the mixed crystal includes a reactive liquid crystal monomer and a photoinitiator, or the mixed crystal includes a conventional nematic liquid crystal, a reactive liquid crystal monomer and a photoinitiator. Specifically, a mixed crystal is filled into the cavity of a standard liquid crystal cell to form a liquid crystal layer, thereby obtaining a liquid crystal device. The mixed crystal may include reactive liquid crystal monomers, reactive liquid crystal monomers and ordinary nematic liquid crystals, reactive liquid crystal monomers and photoinitiators, or ordinary nematic liquid crystals, reactive liquid crystal monomers and photoinitiators. The reactive liquid crystal monomers are selected according to actual needs, and this embodiment of the invention does not limit their selection. The ordinary nematic liquid crystals are selected according to actual needs, and this embodiment of the invention does not limit their selection. The photoinitiator is selected according to actual needs, and this embodiment of the invention does not limit its selection.

[0053] S602. Power on the liquid crystal device and perform ultraviolet exposure curing to pixelate the liquid crystal device to obtain a pixelated liquid crystal device.

[0054] Specifically, the liquid crystal device is electrically driven, causing each pixel in the liquid crystal layer of the liquid crystal device to form its own rotation angle. Simultaneously, the liquid crystal device is subjected to pixelated ultraviolet exposure curing, i.e., ultraviolet light is used to irradiate the liquid crystal device, initiating a photopolymerization reaction in the liquid crystal layer, thereby fixing the rotation angle of each pixel in the liquid crystal layer, resulting in a pixelated liquid crystal device. The voltage applied to the liquid crystal device is set according to actual needs, and this embodiment of the invention does not impose a limitation.

[0055] The method for fabricating a pixelated liquid crystal device provided in this invention involves filling a standard liquid crystal cell with mixed crystals to obtain the liquid crystal device. The mixed crystals include reactive liquid crystal monomers, reactive liquid crystal monomers and ordinary nematic liquid crystals, reactive liquid crystal monomers and photoinitiators, or ordinary nematic liquid crystals, reactive liquid crystal monomers and photoinitiators. The liquid crystal device is then electrically driven and pixelated by ultraviolet exposure curing to obtain the pixelated liquid crystal device, thus reducing the fabrication cost of the pixelated liquid crystal device.

[0056] Based on the above embodiments, the mixed crystal further includes reactive liquid crystal monomers, and when the mixed crystal includes only reactive liquid crystal monomers, the mass fraction of the reactive liquid crystal monomers is 100%.

[0057] Based on the above embodiments, further, the mass fraction of the reactive liquid crystal monomer in the mixed crystal is greater than or equal to 80% and less than 100%, and the mass fraction of the photoinitiator is greater than 0 and less than or equal to 20%. Preferably, the mass fraction of the reactive liquid crystal monomer is greater than or equal to 90% and less than or equal to 95%, and the mass fraction of the photoinitiator is greater than or equal to 5% and less than or equal to 10%.

[0058] For example, the reactive liquid crystal monomer has a mass fraction of 92%, and the photoinitiator has a mass fraction of 8%.

[0059] The reactive liquid crystal monomer is used to construct a solid, anisotropic liquid crystal layer; the photoinitiator, as a key component in the ultraviolet curing system, is used to absorb ultraviolet photons of a specific wavelength and generate active free radicals through a series of photophysical and photochemical processes. The active free radicals initiate a chain polymerization reaction of the reactive liquid crystal monomer to form a cured structure.

[0060] Based on the above embodiments, further, the mass fraction of the reactive liquid crystal monomer in the mixed crystal is greater than or equal to 1% and less than 100%, and the mass fraction of the ordinary nematic liquid crystal is greater than or equal to 0 and less than or equal to 99%. Preferably, the mass fraction of the reactive liquid crystal monomer is greater than or equal to 50% and less than or equal to 80%, and the mass fraction of the ordinary nematic liquid crystal is greater than or equal to 20% and less than or equal to 50%.

[0061] For example, the reactive liquid crystal monomer has a mass fraction of 60%, and the ordinary nematic liquid crystal has a mass fraction of 40%.

[0062] Based on the above embodiments, further, in the mixed crystal, the mass fraction of the ordinary nematic liquid crystal is greater than 0 and less than 99%, the mass fraction of the reactive liquid crystal monomer is greater than 1% and less than 100%, and the mass fraction of the photoinitiator is greater than 0 and less than or equal to 20%. Preferably, the mass fraction of the reactive liquid crystal monomer is greater than or equal to 20% and less than or equal to 80%, the mass fraction of the ordinary nematic liquid crystal is greater than or equal to 20% and less than or equal to 50%, and the mass fraction of the photoinitiator is greater than or equal to 0.5% and less than or equal to 2%.

[0063] For example, the mass fraction of the ordinary nematic liquid crystal is 10%, the mass fraction of the reactive liquid crystal monomer is 89%, and the mass fraction of the photoinitiator is 1%.

[0064] By adding the conventional nematic liquid crystal to the mixed crystal, the aging of the mixed crystal can be slowed down. The photoinitiator can promote the fusion of the conventional nematic liquid crystal and the reactive liquid crystal monomer.

[0065] Based on the above embodiments, the ordinary nematic liquid crystal further comprises E7 liquid crystal, 5CB liquid crystal, or MLC-2065 liquid crystal. E7 liquid crystal is a single-component nematic liquid crystal with the chemical name 4-pentyl-4'-cyanobiphenyl. 5CB liquid crystal is a multi-component nematic liquid crystal mixture composed of various cyanobiphenyl / terphenyl compounds. MLC-2065 liquid crystal is a high-performance multi-component nematic liquid crystal mixture composed of various compounds containing polar groups such as fluorine.

[0066] Based on the above embodiments, the reactive liquid crystal monomer is further described as RM257, RM82 or RM23.

[0067] RM257 is a typical nematic liquid crystal monomer with dual-terminal acrylate functionalization. Its chemical name is 1,4-bis-[4-(3-acryloyloxypropoxy)benzoyloxy]-2-methylbenzene, which can undergo polymerization under ultraviolet light irradiation and photoinitiator action.

[0068] RM82 has a lower melting point than RM257, better solubility when mixed with other liquid crystals, and is more stable at room temperature or lower temperatures.

[0069] RM23 can be used to adjust the crosslinking density, hardness, flexibility, and adhesion of the final polymer.

[0070] Based on the above embodiments, the photoinitiator is further described as Irgacure 651 or Irgacure 184.

[0071] Specifically, Irgacure651, or 2,2-dimethoxy-2-phenylacetophenone, is a highly efficient free radical photoinitiator that can absorb energy in the ultraviolet light band and decompose to generate free radicals, thus initiating photopolymerization reactions.

[0072] Irgacure 184, chemically known as 1-hydroxycyclohexylbenzophenone, has high photoinitiation efficiency, fast curing speed, good resistance to yellowing, good thermal stability, balanced overall performance, and strong versatility.

[0073] In one implementation, the spectral filtering characteristic curve of the 5×5 spectral filter array is as follows: Figure 7 As shown, the vertical axis represents normalized transmittance, with values ​​between 0 and 1, and the horizontal axis represents the wavelength channel number, from 0 to 30 (31 in total). This covers the 400-700nm range, with each wavelength channel spaced 10nm apart. Each color represents the spectral filtering characteristics of a specific pixel. The spectral filtering characteristics between different pixel channels exhibit high non-correlation, involving 31 wavelength channels covering the 400-700nm wavelength range. High non-correlation within the encoding matrix indicates that each encoding channel can capture less relevant information, representing higher encoding efficiency.

[0074] The transmission rate correlation coefficient matrix among the 31 wavelength channels of the above example liquid crystal filter device is as follows: Figure 8 As shown, it exhibits a significantly high degree of uncorrelation, meaning that only a very small number of correlation coefficients are higher than 0.9 near the diagonal, while the majority of the correlation values ​​are lower than 0.3, reaching the forefront of the field in terms of performance.

[0075] Based on snapshot spectral imaging using a spectral filtering array, this application proposes a simple, stable, and low-cost scheme for constructing a spectral filtering array using pixelated liquid crystal devices and polarizers, thereby achieving a high-performance spectral filtering array.

[0076] The method for fabricating pixelated liquid crystal devices proposed in this application uses conventional materials with low processing costs, making it easy to control process parameters during processing. The overall device structure is simple and stable, and it has extremely high value for widespread application.

[0077] In the description of this specification, the references to terms such as "an embodiment," "a specific embodiment," "some embodiments," "for example," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0078] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. 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 spectral image sensor, characterized in that, It includes an image detection array and a spectral filtering array, which are stacked together. The spectral filtering array includes a pair of polarizers and a pixelated liquid crystal device sandwiched between the pair of polarizers. The liquid crystal in each pixel region of the pixelated liquid crystal device has a fixed out-of-plane rotation angle.

2. The spectral image sensor according to claim 1, characterized in that, The transmission axes of the two polarizers in the pair are arranged at an arbitrary angle.

3. The spectral image sensor according to claim 1, characterized in that, The liquid crystal orientation of each pixel region in the pixelated liquid crystal device is a parallel orientation mode. The liquid crystal orientation is not parallel and not perpendicular to the light transmission axis of either of the pair of polarizers. The out-of-plane rotation angle of the liquid crystal in each pixel region is fixed to an arbitrary angle that is not exactly the same.

4. A snapshot spectral imaging system, characterized in that, Includes the spectral image sensor, imaging lens, and data processing module as described in any one of claims 1 to 3, wherein: The imaging lens is used to map the target scene onto the spectral image sensor; The spectral image sensor is used for spectral image modulation and detection to obtain the acquired signal; The data processing module is used to perform signal processing on the acquired signals.

5. A method for fabricating a pixelated liquid crystal device, characterized in that, include: A liquid crystal device is obtained by filling a standard liquid crystal cell with a mixed crystal; wherein the mixed crystal includes a reactive liquid crystal monomer, the mixed crystal includes a reactive liquid crystal monomer and a conventional nematic liquid crystal, the mixed crystal includes a reactive liquid crystal monomer and a photoinitiator, or the mixed crystal includes a conventional nematic liquid crystal, a reactive liquid crystal monomer and a photoinitiator. The liquid crystal device is driven by power and then pixelated by ultraviolet exposure curing to obtain a pixelated liquid crystal device.

6. The method according to claim 5, characterized in that, The mass fraction of the reactive liquid crystal monomer in the mixed crystal is greater than or equal to 80% and less than 100%, and the mass fraction of the photoinitiator is greater than 0 and less than or equal to 20%.

7. The method according to claim 5, characterized in that, The mass fraction of the reactive liquid crystal monomer in the mixed crystal is greater than or equal to 1% and less than 100%, and the mass fraction of the ordinary nematic liquid crystal is greater than or equal to 0 and less than or equal to 99%.

8. The method according to claim 5, characterized in that, In the mixed crystal, the mass fraction of the ordinary nematic liquid crystal is greater than 0 and less than 99%, the mass fraction of the reactive liquid crystal monomer is greater than 1% and less than 100%, and the mass fraction of the photoinitiator is greater than 0 and less than or equal to 20%.

9. The method according to claim 5, characterized in that, The ordinary nematic liquid crystal uses E7 liquid crystal, 5CB liquid crystal, or MLC-2065 liquid crystal.

10. The method according to claim 5, characterized in that, The reactive liquid crystal monomer is RM257, RM82 or RM23.

11. The method according to claim 5, characterized in that, The photoinitiator used is Irgacure 651 or Irgacure 184.

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