Multi-dimensional light field regulation and control method and system based on liquid crystal coherent pixels

Abstract

The invention discloses a multi-dimensional light field regulation and control method and system based on liquid crystal coherent pixels. The method comprises the following steps: firstly, calculating the orientation of each unit in a liquid crystal array according to a preset near-field target pattern and a far-field target image, and respectively realizing phase and amplitude coding by utilizing the orientation of the liquid crystal units and the phase difference between the adjacent units; then, a collaborative objective function is established and optimized, the function considers the matching degree of a near-field pattern and a far-field phase at the same time, and finally a unified liquid crystal orientation matrix is generated. The liquid crystal element prepared according to the matrix can respectively present different corresponding nano printing patterns in a near field under the conditions of different polarization states, incident angles or wavelengths of irradiation light, and synchronously generate a clear holographic target image in a far field. The corresponding system comprises a liquid crystal element with the orientation characteristics, laser modules with different wavelengths and an image acquisition module. Near-field multi-channel dynamic display and far-field color holographic imaging are realized on a single liquid crystal device for the first time, and the device has the advantages of large information capacity, high function integration level and dynamic regulation and control, and has great application potential in the fields of high-end anti-counterfeiting, augmented reality and the like.

Description

Technical Field

[0001] This invention relates to the field of liquid crystal light field modulation technology, and in particular to a multidimensional light field modulation method and system based on liquid crystal coherent pixels. Background Technology

[0002] Liquid crystal materials have attracted increasing attention in the field of planar optical devices due to their unique birefringence properties, reconfigurable molecular orientation, and mature large-scale fabrication processes. By precisely controlling the arrangement of liquid crystal molecules, the amplitude and phase of light waves can be flexibly modulated, which has enabled liquid crystal optical elements to demonstrate great potential in fields such as displays, information encryption, and beam shaping.

[0003] In recent years, significant progress has been made in multidimensional light field multiplexing technology for liquid crystal devices. Researchers have designed a series of optical elements with diverse functions, including polarization gratings and orbital angular momentum beam generators, greatly enriching the functionality of planar optical devices. Meanwhile, novel planar optical design concepts such as metasurfaces have provided design ideas for developing dynamic light field manipulation schemes for liquid crystals. Against this technological backdrop, multidimensional multiplexing strategies have achieved several breakthroughs: on the one hand, by integrating holographic encryption algorithms, cascading, and displacement multiplexing strategies, the information encoding capacity has been improved, enabling multi-channel display of information; on the other hand, by combining plasmonic structures or leveraging advanced optimization algorithms, flexible dynamic control has been further achieved in multiple physical dimensions such as structural color and polarization state. These advancements fully demonstrate the enormous potential of liquid crystal technology in high-end anti-counterfeiting, virtual reality, and other application scenarios.

[0004] While these advancements have greatly enriched the functionality of liquid crystal devices, current work largely focuses on the multiplexing of a single dimension or a limited number of channels. Existing research still faces a key challenge: how to integrate multiple functions within the same liquid crystal device to achieve dynamic control of the near and far fields.

[0005] Therefore, a multidimensional light field modulation method based on liquid crystal coherent pixels is needed. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a multi-dimensional light field control method based on liquid crystal coherent pixels. This method generates a global orientation matrix by co-optimizing the liquid crystal orientation array, thereby realizing the functional integration and on-demand switching of near-field intensity-coded imaging and far-field phase holographic imaging on a single dynamically controllable liquid crystal device.

[0007] To achieve the above objectives, the present invention provides the following technical solution: The multidimensional light field modulation method based on liquid crystal coherent pixels provided by this invention includes the following steps: S1. Design of the liquid crystal coherent pixel array: Based on the target near-field pattern and the target far-field image, design the orientation of each liquid crystal cell in the liquid crystal array. Multiple liquid crystal cells are defined as a liquid crystal coherent pixel, and each liquid crystal coherent pixel corresponds to a pixel in the target image. Liquid crystal cells at different positions within the same liquid crystal coherent pixel are configured with a non-uniform orientation angular distribution, such that the total phase difference δ between adjacent liquid crystal cells satisfies: δ=2πd·sinθ / λ+2σΔφ Where d is the unit spacing, θ is the incident angle of light, λ is the working wavelength, σ is the polarization correlation coefficient, and Δφ is the rotation angle difference between adjacent units. Binarized light intensity encoding is achieved by adjusting the total phase difference δ. This constraint is a near-field display constraint.

[0008] Meanwhile, the far-field angle design orientation can be established based on the holographic algorithm (Gerchberg-Saxton, GS algorithm) or the off-axis illumination color holographic algorithm.

[0009] The final orientation of the liquid crystal array needs to simultaneously satisfy the local geometric phase constraint (Δφ) from the near field and the global holographic phase constraint (ψ) from the far field. The holographic phase distribution (ψ) is used as the starting angle of the coherent pixels, and the orientation angle matrix distribution of the coherent pixels is designed and implemented according to the orientation angle difference (Δφ) of the corresponding pixels. S2. Liquid Crystal Orientation Co-optimization Process: Establishing the Co-optimization Objective Function: E total =w1·E near +w2·E far E near To adjust the deviation between the angular difference of the liquid crystal cell and the required angular difference of the target near-field pattern, E far To adjust the deviation between the phase distribution of the liquid crystal cells and the required holographic phase distribution of the target far-field image, w1 and w2 are weighting coefficients; Within a preset adjustment range, iterates through all possible phase adjustment combinations within each pixel with a fixed step size, selecting the combination that makes the target function E... total Minimize the combination to generate the global liquid crystal orientation matrix; S3. Light field manipulation and imaging: A liquid crystal element is prepared according to the global liquid crystal alignment matrix; by changing at least one physical dimension parameter of the light incident on the liquid crystal element, an image corresponding to the target near-field pattern is obtained in the near field, and a holographic image corresponding to the target far-field image is obtained in the far field.

[0010] Furthermore, in step S3, changing the physical dimension parameters of the incident light includes switching the circular polarization chirality of the incident light.

[0011] Furthermore, in step S3, changing the physical dimension parameters of the incident light includes changing the angle of the incident light relative to the liquid crystal element.

[0012] Furthermore, in step S1, the target far-field image is a color image, which is decomposed into three color channel images: red, green, and blue. Correspondingly, in step S3, three beams of light with different wavelengths (red, green, and blue) are simultaneously incident on the liquid crystal element at a preset off-axis angle to synthesize a color holographic image in the far field.

[0013] Furthermore, the weighting coefficients w1 and w2 in step S2 are equal.

[0014] The multi-dimensional light field control system based on liquid crystal coherent pixels provided by the present invention includes liquid crystal coherent pixel elements, a light source and illumination module, a control module, and an imaging module; The orientation of the liquid crystal array of the liquid crystal coherent pixel element is set according to the global liquid crystal orientation matrix generated according to steps S1 and S2; wherein the liquid crystal array is composed of multiple liquid crystal coherent pixels, each liquid crystal coherent pixel contains multiple liquid crystal units, and the liquid crystal units within the same liquid crystal coherent pixel have a non-uniform orientation angle distribution. The light source and illumination module are used to generate and guide at least one beam of light to be incident on the liquid crystal coherent pixel element with specific parameters; The control module is used to control the light source and the illumination module to change at least one physical dimension parameter of the light incident on the liquid crystal coherent pixel element. The imaging module is used to receive near-field modulated light and far-field diffracted light from the liquid crystal coherent pixel element, respectively, and to acquire the corresponding near-field image and far-field holographic image.

[0015] Furthermore, the light source and illumination module includes a polarization state generation unit, which includes a linear polarizer and a quarter-wave plate arranged sequentially along the optical path to generate left-handed or right-handed circularly polarized light; the control module switches the circular polarization chirality of the incident light by controlling the polarization state generation unit.

[0016] Furthermore, the light source and illumination module includes an angle adjustment unit for changing the angle of the incident light relative to the surface of the liquid crystal coherent pixel element; the control module controls the angle adjustment unit to change the incident angle.

[0017] Furthermore, the light source and illumination module includes a red laser, a green laser, and a blue laser, as well as optical components for coupling the three laser beams to the same optical path at different preset off-axis angles or incident on the liquid crystal coherent pixel element at different angles.

[0018] Furthermore, the imaging module includes an aperture stop for filtering out light of non-target diffraction orders.

[0019] The beneficial effects of this invention are as follows: Breakthrough in functional integration limitations of traditional liquid crystal optical devices: For the first time, simultaneous switching of near-field multi-channel nanoprinted patterns and far-field full-color holographic imaging were achieved on a single liquid crystal element. This solves the key problem of existing technologies' inability to simultaneously achieve multi-channel optical control in the near and far fields, greatly improving the functional integration of the device.

[0020] This method significantly enhances the information capacity and control dimensionality of the light field: through the phase design of "liquid crystal coherent pixels" and algorithmic optimization of near-field coding and far-field holography, it achieves independent and coordinated control of multiple physical dimensions such as the polarization state, incident angle, and wavelength of the incident light. This multidimensional multiplexing strategy significantly expands the information carrying capacity and coding capacity of a single device.

[0021] A high-quality, low-crosstalk full-color holographic display was achieved: by introducing an off-axis illumination strategy for the three primary colors (red, green, and blue) and combining it with wavelength-dependent phase design, the far-field display was successfully extended from monochrome to full color. This scheme effectively suppressed crosstalk between multiple channels, ensuring the accuracy of color image reproduction and the independence of information from each channel.

[0022] Combining high performance and practical potential: The liquid crystal coherent pixel encoding method on which this solution relies is compatible with existing mature liquid crystal material systems and manufacturing processes. This not only ensures the stability and reliability of device performance, but also has the outstanding advantages of low cost and easy large-scale production. It provides a feasible technical path for practical applications in fields such as high-density optical storage, dynamic holographic anti-counterfeiting, and virtual / augmented reality displays.

[0023] The above and other objects, advantages, and features of the present invention will be more fully set forth and demonstrated through the following detailed description of specific embodiments in conjunction with the accompanying drawings. Those skilled in the art, upon referring to the following detailed description and the accompanying drawings, will be able to better understand and realize the above advantages of the present invention. Other objects, features, and advantages of the present invention will become clearer after being described in detail in the detailed description section in conjunction with the accompanying drawings. Attached Figure Description

[0024] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following drawings are provided for illustration.

[0025] Figure 1 A schematic diagram illustrating the process of multidimensional light field modulation based on liquid crystal coherent pixels; Figure 2 Schematic diagram of multi-functional imaging based on multi-dimensional light field modulation of liquid crystal coherent pixels; Figure 3 Schematic diagrams and results related to the experimental verification of near-field polarization multiplexing and angle multiplexing devices; Figure 4 A schematic diagram and results of a near-field nanoprinted and far-field holographic multichannel multiplexed device; Figure 5 This is a schematic diagram and results of an experimental setup for a co-multiplexed device combining color holography and near-field nanoprinting. Detailed Implementation

[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0027] Example 1 like Figure 1 (a) shows the multi-dimensional light field modulation method based on liquid crystal coherent pixels provided in this embodiment. This method is a method for designing near-field light field modulation devices based on liquid crystal coherent pixels, including the following steps: S1. Design the angle of the liquid crystal coherent pixel liquid crystal unit. Two independent patterns are selected as near-field imaging targets. In this embodiment, the orientation of the liquid crystal array is designed so that the two patterns are excited and imaged by incident light with different physical parameters.

[0028] Designing a coherent liquid crystal pixel array: Based on the target near-field pattern, the orientation of each liquid crystal cell in the liquid crystal array is designed such that the total phase difference δ between adjacent liquid crystal cells satisfies the following physical basis: δ=2πd·sinθ / λ+2σΔφ Where d is the center-to-center spacing of the liquid crystal cells, θ is the incident angle of the light, λ is the operating wavelength of the incident light, σ is the polarization chirality coefficient of the incident light (σ=+1 for RCP, σ=-1 for LCP), and Δφ is the preset orientation angle difference of liquid crystal molecules between adjacent cells. When the total phase difference δ is close to 0 or an even multiple of π, the light intensity coherence is enhanced; when δ is close to an odd multiple of π, the light intensity coherence is destructive. By precisely designing the Δφ distribution within each "coherent pixel" (composed of multiple liquid crystal cells), different binarized intensity distributions, i.e., target patterns, can be "carved" for different combinations of (θ,σ) of incident light.

[0029] Operating wavelength: λ=532nm (green light) laser, which is common in the visible light band, is selected as the illumination source.

[0030] Cell pitch: The liquid crystal cell pitch d in this example is set to 10.8 μm due to the processing conditions in this laboratory; Orientation angle discretization: Due to the current limitations in the precision of digital photoelectric alignment technology, the orientation angle of the liquid crystal cell and the value of the orientation angle difference Δφ between adjacent cells are discretized with a minimum step size of 10°. During the design process, the algorithm selects the solution that best meets the light intensity encoding requirements of the target channel for each spatial position from the discrete set of Δφ values.

[0031] Coherent pixel definition: A 10×10 liquid crystal unit is defined as a "coherent pixel," responsible for reproducing a single pixel in the target image. The sample to be prepared contains a total of 50×50 such coherent pixels, corresponding to a physical sample size of 5.4mm×5.4mm. It should be noted that the number of liquid crystal units contained in the coherent pixels in each embodiment is merely an example. Those skilled in the art can flexibly determine the number of units and their arrangement in each coherent pixel based on factors such as the resolution of the target image, device size, and processing precision.

[0032] In this embodiment, multiple liquid crystal cells are defined as a liquid crystal coherent pixel, and each liquid crystal coherent pixel corresponds to a pixel cell in the target image. Liquid crystal cells at different positions within the same liquid crystal coherent pixel are configured to have a non-uniform orientation angle distribution. Based on the calculated required orientation angle difference between units within a coherent liquid crystal pixel, the initial orientation angle of the first column of liquid crystal units in this example is first determined (set to 0° in this example; this initial value can be freely selected according to design requirements). Using this initial value as a reference, the orientation angles of all units in the first row are recursively calculated along the row direction according to the preset angle difference, thus generating the first row orientation angle row vector of the pixel. Subsequently, this row vector is copied along the column direction to quickly generate the two-dimensional orientation angle distribution matrix of all 10×10 liquid crystal units within the pixel, completing the design of a single coherent pixel. To ensure the coherence and performance of the overall orientation field when multiple coherent pixels are arranged, the orientation designs of adjacent pixels need to be connected. Specifically, the orientation angle of the last column unit of the current pixel is used as the starting reference value for its next adjacent pixel, and calculations continue according to the internal angle difference rules of that pixel. The orientation of each liquid crystal unit in the liquid crystal array is designed according to this method.

[0033] S2. Liquid crystal preparation using photo-alignment technology Substrate pretreatment and alignment layer coating: The transparent glass substrate is cleaned, dried, cut, and UV-activated. Subsequently, a solution of the photo-alignment material SD1 is spin-coated to form a uniform thin film. An execution program is written using specialized software based on the liquid crystal molecule alignment angle information. After the above process is completed, the substrate coated with the alignment layer is fixed on the DMD exposure platform for substrate horizontal calibration and focal plane positioning to ensure processing accuracy. Finally, exposure is performed. A toluene-based liquid crystal mixture (RM257:14%, 184 photoinitiator:1%, toluene:85%) is prepared. The liquid crystal is dropped onto the substrate using a pipette, and under nitrogen protection, multiple spin-coatings are performed to achieve a 532nm half-wave thickness (approximately 2.6µm) liquid crystal layer deposition. The composite structure device is placed in a 322nm UV curing system and subjected to a 180-second photopolymerization reaction under unpolarized light irradiation, ultimately forming a liquid crystal polymer optical thin film with a stable alignment structure.

[0034] S3. Verification System and Experimental Results Building such Figure 3 The optical path shown in (a) mainly includes: a 532nm laser, a beam expander and collimator system, a polarization beam generation / switching module composed of a linear polarizer and a quarter-wave plate, a sample stage, and an imaging lens and camera for receiving near-field diffracted light. An aperture stop is provided in the optical path to filter out interference light of non-target diffraction orders.

[0035] By constructing an optical path and performing light field modulation and imaging: a liquid crystal element is prepared according to the global liquid crystal alignment matrix; by changing at least one physical dimension parameter of the light incident on the liquid crystal element, an image corresponding to the target near-field pattern is obtained in the near field, and a holographic image corresponding to the target far-field image is obtained in the far field.

[0036] Figure 3 (b) Near-field multiplexed liquid crystal sample photograph: This shows the appearance of the actual prepared sample. A ruler is attached on the left as a scale reference. The liquid crystal cell pitch is 10.8 mm. m, with a total size of 5.4mm × 5.4mm. Figure 3 b1 in the sample is a polarization multiplexed sample. Figure 3 b2 in the sample is an angle reuse sample. Figure 3 (c) Polarization multiplexing experiment results (sample 1): Under 532nm green laser illumination, when the incident light switches between right-hand circular polarization (RCP) and left-hand circular polarization (LCP), the experimentally measured near-field image clearly switches between "standing human figure" and "fallen human figure", which is highly consistent with the target design. Figure 3 (d) Angle multiplexing experiment results (sample 2): Under a fixed polarization state, by changing the incident / observation angle, the experiment successfully achieved the switching between "smiley face" and "sad face" patterns, verifying the independent control capability of coherent pixels on the incident wave vector.

[0037] The device can decode and display completely independent images in the near field based on the polarization state or angle of the incident light, achieving information multiplexing across two physical dimensions. The limited contrast and pixel-to-pixel brightness unevenness observed in the experiment are mainly attributed to the phase quantization error introduced by the 10° discretization step size of the orientation angle Δφ, and the design freedom constraints imposed by the fixed cell spacing d. Improving process precision to reduce the Δφ step size, or co-optimizing d and λ, are direct ways to further improve device performance in the future.

[0038] This example successfully verifies the feasibility of a multi-dimensional light field manipulation method based on liquid crystal coherent pixels for basic near-field multiplexing. By using a single, statically fabricated liquid crystal element and simply changing the polarization or angle of the incident light, dynamic selection and display of multi-channel information can be achieved, demonstrating the application potential of this invention in information encoding, dynamic display, and other fields.

[0039] Example 2 like Figure 1 As shown in (b) in the figure, Figure 1 (b) is a schematic diagram of a multi-dimensional light field modulation method based on liquid crystal coherent pixels. This embodiment details the specific implementation process of the method from the perspective of near-field and far-field functional synergy under a single wavelength, as follows: Based on the near-field multi-channel control implemented in Example 1, this embodiment introduces far-field holographic functionality. This method uses a collaborative optimization algorithm to simultaneously achieve near-field pattern switching and far-field holographic imaging on a single liquid crystal element.

[0040] S1. Identification of near-field and far-field targets and preliminary phase design A single wavelength (λ=532nm in this embodiment) was selected as the operating wavelength. Design objectives include: Near-field dual-channel target: two independent binarized patterns; Far-field holographic target: an image of a target.

[0041] Based on this, preliminary phase design is performed: For the two near-field target patterns, according to the principle described in Example 1, the pixel-level liquid crystal cell orientation angle difference distribution matrix Δφ required to achieve high-contrast binarization imaging is calculated. These two matrices define the geometric phase constraints required within each "coherent pixel" (composed of 4×4 liquid crystal cells) to achieve the near-field switching function. Figure 4 (a1 in the original text). The GS algorithm is used to calculate the corresponding initial holographic phase distribution matrix ψ(a1) of the far-field target image. Figure 4 (a2 in the middle).

[0042] Therefore, the final orientation of the liquid crystal array needs to simultaneously satisfy the orientation constraint (Δφ) from the near field and the holographic phase constraint (ψ) from the far field. The holographic phase distribution (ψ) is used as the starting angle of the coherent pixels, and the orientation angle matrix distribution of the coherent pixels is designed and implemented based on the orientation angle difference (Δφ) corresponding to the pixels. Figure 4 (a3 in the model) to achieve the preliminary design of the orientation angle of 125×125 coherent pixels.

[0043] S2, Collaborative Optimization Processing and Global Orientation Matrix Generation To address the aforementioned multi-objective constraint problem, this invention proposes the following collaborative optimization method: Establish a collaborative optimization objective function: E total =w1×E near +w2×E far Where: E near E represents the sum of the absolute deviations between the actual liquid crystal cell orientation angle difference within a coherent pixel and the corresponding pixel target angle difference Δφ after optimization. far This represents the deviation between the phase distribution of the entire liquid crystal array and the target holographic phase ψ after optimization. w1 and w2 are weighting coefficients used to balance the relative importance of near-field and far-field imaging quality during the optimization process. This embodiment demonstrates equalization optimization using an equal weighting setting of w1=w2=1. In practical applications, this weighting ratio can be adjusted according to specific needs (emphasis on near-field or far-field imaging quality).

[0044] Each liquid crystal coherent pixel (4×4 units in this example) is treated as an independent optimization unit. Within a preset orientation angle adjustment range (±80° in this example), all possible phase adjustment combinations for that pixel are systematically traversed using a fixed step size allowed by the process (10° in this example). For each combination, its impact on the global phase distribution is calculated, and its effect on E is evaluated separately. near and E far The contribution of the combination is calculated, and the corresponding E is calculated. total Select E total The minimum phase adjustment combination generates a global liquid crystal alignment matrix that can simultaneously and optimally approximate the phase requirements of near-field dual-channel encoding and far-field holography. Figure 4 (a4 in the diagram). This phase matrix design serves as the direct basis for subsequent device fabrication.

[0045] S3. Device fabrication and optical verification Component fabrication: Based on the global liquid crystal alignment matrix generated in S2, liquid crystal coherent pixel elements were fabricated using a digital light-controlled alignment process (such as DMD exposure) similar to that in Example 1. Key process parameters (alignment material, liquid crystal layer thickness ~2.6 μm) remained consistent, and the physical size of the sample was 5.4 mm × 5.4 mm.

[0046] In this embodiment, the liquid crystal array is composed of multiple liquid crystal coherent pixels, each liquid crystal coherent pixel contains multiple liquid crystal units, and the liquid crystal units within the same liquid crystal coherent pixel have a non-uniform orientation angle distribution. System setup: Based on the near-field imaging optical path in Example 1, a far-field imaging optical path is added. This optical path includes a Fourier transform lens that focuses the diffracted light behind the liquid crystal element onto its focal plane (i.e., the spectral plane), where a camera receives the far-field holographic image.

[0047] Imaging verification: Using a 532nm laser, when the incident light is RCP, a clear "human figure" pattern was observed in the near field (corresponding to...). Figure 4 (c)); When switching to LCP, the near-field pattern simultaneously switches to a clear "robot" pattern (corresponding to... Figure 4 (d)). Near-field polarization multiplexing dynamic display was achieved. Under the same illumination conditions, the camera located at the focal plane of the Fourier lens successfully captured a clear "HOLO" hologram (corresponding to...). Figure 4 (b)). The image coexists with the near-field pattern and is of good quality.

[0048] This embodiment successfully addresses the technical challenge of fusing near-field and far-field phases within the same set of liquid crystal cell orientations by introducing and detailing a collaborative optimization algorithm. Experimental results ( Figure 4 This strongly confirms that the single liquid crystal element designed and fabricated based on this method can synchronously and independently control near-field display information and far-field holographic images under single-wavelength illumination, marking a breakthrough in multi-dimensional light field integration.

[0049] Example 3 like Figure 1 As shown in (c) of the figure, this embodiment details the implementation process of the method from the perspective of synergistic control of near-field multiplexing and color far-field holography: This embodiment, based on the single-wavelength near-field-far-field coordination achieved in Embodiment 2, further extends far-field imaging to the full-color dimension, demonstrating the advanced performance and broad application prospects of the present invention in multi-wavelength multiplexing and complex light field integration. Through off-axis illumination design and multi-channel collaborative optimization, near-field dual-channel switching and far-field color holographic display are simultaneously realized on a single liquid crystal element.

[0050] S1. Near-field and far-field constraint design Two binarized patterns are set as near-field display content. They will be excited by left-handed circularly polarized light (LCP) and right-handed circularly polarized light (RCP), respectively. The near-field coherent pixel angle difference constraint is obtained using the coherent pixel angle difference calculation principle in Example 1.

[0051] A color image is selected as the far-field holographic target. First, the color image is decomposed into three independent color channels: red (R), green (G), and blue (B), corresponding to: R channel: wavelength λ R =633nm; G channel: wavelength λ G =532nm; B channel: wavelength λ B =473nm; Holographic phase calculation: For each color channel of the monochrome image, the GS algorithm is used to calculate the corresponding initial holographic phase distribution matrix and then vector superposition is performed to obtain the color holographic phase.

[0052] To avoid crosstalk between the three color channels during far-field reconstruction, this embodiment introduces a precisely designed off-axis illumination strategy.

[0053] Off-axis angle calculation principle: Each wavelength channel is assigned a unique, non-overlapping offset position (ΔX, ΔY) (in pixels) on the spectral plane. The transverse wave vector component to be carried by the corresponding incident plane wave is determined by the following general formulas: θx = arcsin(λΔX / (Nd)); θy = arcsin(λΔY / (Nd)); where θ is in radians. Where N is the total number of cells in the one-dimensional direction of the liquid crystal array, d is the cell spacing (10.8 μm is used in this embodiment), and λ is the wavelength of the corresponding channel. Specific parameters of the embodiment: Through optimized design, the off-axis angle set for this embodiment (the angle meaning is as follows) Figure 5 As shown in (b) in the diagram: Red channel (633nm): θx≈-0.84°, θy≈-0.84°; Green channel (532nm): θx≈0.71°, θy≈-0.71°; Blue channel (473nm): θx≈-0.63°, θy≈0.63°. These off-axis angles are converted into corresponding tilt phase factors and superimposed onto the initial holographic phase matrices of the three channels to form the final far-field multi-wavelength phase. This ensures that when each color of light is incident at the designed angle, color imaging can be achieved, and that interference images of different colors do not spatially overlap with the target color image.

[0054] S2, Collaborative Optimization Processing and Global Orientation Matrix Generation Input all of the following constraints into the collaborative optimization algorithm framework described in Example 2: Near-field constraint: The orientation difference from the near-field pattern requires Δφ.

[0055] Far-field multi-wavelength constraint: Holographic phase requirement from the red, green, and blue channels, containing off-axis information.

[0056] The objective function is optimized in principle in the same way as in Example 2. The algorithm iterates through the search and finally generates a single, unified global liquid crystal orientation matrix. This matrix is ​​a compromise optimal solution that can simultaneously and best approximate the complex multi-objective set of "near-field polarization multiplexing" and "far-field color off-axis holography".

[0057] S3. Device fabrication and optical verification Based on the aforementioned global alignment matrix, high-precision digital optical alignment technology was used to fabricate liquid crystal elements, with a sample physical size of 5.4 mm × 5.4 mm. The process details remained consistent with Examples 1 and 2 to ensure the accurate fabrication of the alignment structure.

[0058] Multi-wavelength off-axis illumination system experimental system, such as Figure 5 As shown in (a), it mainly includes: a light source consisting of three monochromatic lasers: red (633nm), green (532nm), and blue (473nm). The three laser beams are used to illuminate the image at a calculated angle, achieving off-axis incidence. The imaging section includes a near-field imaging optical path (lens and a camera located on the image plane) and a far-field imaging optical path (Fourier lens and a color camera located on its focal plane).

[0059] Turn on the red, green, and blue lasers and ensure they are simultaneously incident on the sample at the designed off-axis angle. For example... Figure 5 As shown in (c), a color camera successfully recorded a richly colored, clearly defined holographic image of a flower on the focal plane (far field) of the Fourier lens. The red, green, and blue channel images are spatially superimposed. Due to the advantages of the off-axis design, crosstalk between channels is effectively suppressed. Illumination is achieved using circularly polarized light of a single wavelength (532 nm), as shown in [image description missing]. Figure 5 (d) and Figure 5 As shown in (e), when the incident light switches between LCP and RCP, the near-field camera clearly captures the corresponding switching of the "L" and "R" patterns, proving the feasibility of the near-field polarization multiplexing function.

[0060] This embodiment successfully extends the operating wavelength from monochromatic to color (red, green, and blue), and through precise off-axis illumination design and multi-target collaborative optimization, simultaneously achieves near-field dual-channel dynamic display and far-field color holographic imaging on a single liquid crystal coherent pixel element. This fully demonstrates that the method proposed in this invention has the following advantages: Multi-dimensional multiplexing capability: It can simultaneously encode and control the near-field and far-field channels of the device independently.

[0061] High-density information integration capability: Integrating multiple optical functions into a thin-layer device greatly improves the information capacity and functional density of the device.

[0062] High performance and practicality: The experimental results demonstrate good imaging quality and color performance. Combined with mature liquid crystal manufacturing processes, this indicates that the technology has strong application potential and practical prospects in fields such as dynamic holographic anti-counterfeiting, color virtual reality, high-density optical storage and information encryption.

[0063] The method provided in this embodiment systematically constructs a liquid crystal multidimensional light field manipulation system from near field to far field and from monochrome to color. By proposing a liquid crystal coherent pixel combination optimization algorithm and working in conjunction with off-axis multi-wavelength design, the target conflict between near-field intensity and far-field phase is optimized, achieving color holography without increasing component complexity.

[0064] The above contains three examples and corresponding diagrams, as follows: Figure 2 As shown, Figure 2 (a) in the diagram represents near-field multiplexing: by switching the chirality (LCP / RCP) of circularly polarized light or changing the incident angle (θ), different independent images can be decoded in the near field of the device; Figure 2 (b) in the figure corresponds to its principle mechanism: design the orientation angle difference (Δφ) of adjacent liquid crystal cells (cell spacing is d), realize binary amplitude encoding, and complete the dynamic switching of images under different incident parameters; Figure 2 (c) Near-field-far-field coordination: By improving the holographic algorithm, the constraints of far-field holography and near-field printing on liquid crystal orientation are optimized and solved, realizing the synchronous generation of near-field dual patterns and far-field holographic images; Figure 2 (d) Color holography: Introducing off-axis illumination of red, green and blue primary colors, and pre-setting the incident angles (ζx, ζy, ζz) corresponding to the wavelengths of red, green and blue, the far-field color image is combined with near-field polarization multiplexing, and finally the information multiplexing of multiple channels is realized.

[0065] The above-described embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A multidimensional light field modulation method based on liquid crystal coherent pixels, characterized in that, Includes the following steps: S1. Design of a liquid crystal coherent pixel array: Based on the target near-field pattern and the target far-field image, design the orientation of each liquid crystal cell in the liquid crystal array; wherein, multiple liquid crystal cells are defined as a liquid crystal coherent pixel, each liquid crystal coherent pixel corresponds to a pixel in the target image, and liquid crystal cells at different positions within the same liquid crystal coherent pixel are configured to have a non-uniform orientation angular distribution, such that the total phase difference δ between adjacent liquid crystal cells satisfies: δ=2πd·sinθ / λ+2σΔφ Where d is the unit spacing, θ is the incident angle of light, λ is the working wavelength, σ is the polarization correlation coefficient, and Δφ is the rotation angle difference between adjacent units. Binarized light intensity encoding is achieved by adjusting the total phase difference δ. Meanwhile, the far-field angle design orientation can be established based on the holographic algorithm (Gerchberg-Saxton, GS algorithm) or the off-axis illumination color holographic algorithm; The final orientation of the liquid crystal array needs to simultaneously satisfy the phase constraint (Δφ) from the near field and the holographic phase constraint (ψ) from the far field. The holographic phase distribution (ψ) is used as the starting angle of the coherent pixels, and the orientation angle matrix distribution of the coherent pixels is designed and implemented according to the orientation angle difference (Δφ) corresponding to the pixels. S2. Liquid Crystal Orientation Co-optimization Process: Establishing the Co-optimization Objective Function: AND total =w1·E near +w2·E far , Among them, E near To adjust the deviation between the angular difference of the liquid crystal cell and the required angular difference of the target near-field pattern, E far To adjust the deviation between the phase distribution of the liquid crystal cells and the required holographic phase distribution of the target far-field image, w1 and w2 are weighting coefficients; Within a preset adjustment range, iterates through all possible phase adjustment combinations within each pixel with a fixed step size, selecting the combination that makes the target function E... total Minimize the combination to generate the global liquid crystal orientation matrix; S3. Light field manipulation and imaging: A liquid crystal element is prepared according to the global liquid crystal alignment matrix; by changing at least one physical dimension parameter of the light incident on the liquid crystal element, an image corresponding to the target near-field pattern is obtained in the near field, while red, green and blue three-wavelength light off-axis illumination is used to obtain a color holographic image corresponding to the target far-field image in the far field.

2. The multidimensional light field modulation method based on liquid crystal coherent pixels as described in claim 1, characterized in that, In step S3, changing the physical dimension parameters of the incident light includes switching the circular polarization chirality of the incident light.

3. The multidimensional light field modulation method based on liquid crystal coherent pixels as described in claim 1, characterized in that, In step S3, changing the physical dimension parameters of the incident light includes changing the angle of the incident light relative to the liquid crystal element.

4. The multidimensional light field modulation method based on liquid crystal coherent pixels as described in claim 1, characterized in that, In step S1, the target far-field image is a color image, which is decomposed into three color channel images: red, green, and blue. Correspondingly, in step S3, three beams of light with different wavelengths (red, green, and blue) are simultaneously incident on the liquid crystal element at a preset off-axis angle to synthesize a color holographic image in the far field.

5. The multidimensional light field modulation method based on liquid crystal coherent pixels as described in claim 1, characterized in that, In step S2, the weighting coefficients w1 and w2 are equal.

6. A multi-dimensional light field modulation system based on liquid crystal coherent pixels, characterized in that, Includes liquid crystal coherent pixel elements, light source and illumination module, control module, and imaging module; The orientation of the liquid crystal coherent pixel element is set by the global liquid crystal orientation matrix generated according to steps S1 and S2 of the method described in claim 1; wherein the liquid crystal array is composed of multiple liquid crystal coherent pixels, each liquid crystal coherent pixel contains multiple liquid crystal units, and the liquid crystal units within the same liquid crystal coherent pixel have a non-uniform orientation angle distribution. The light source and illumination module are used to generate and guide at least one beam of light to be incident on the liquid crystal coherent pixel element with specific parameters; The control module is used to control the light source and the illumination module to change at least one physical dimension parameter of the light incident on the liquid crystal coherent pixel element. The imaging module is used to receive near-field modulated light and far-field diffracted light from the liquid crystal coherent pixel element, respectively, and to acquire the corresponding near-field image and far-field holographic image.

7. The multi-dimensional light field modulation system based on liquid crystal coherent pixels as described in claim 6, characterized in that, The light source and illumination module includes a polarization state generation unit, which includes a linear polarizer and a quarter-wave plate arranged sequentially along the optical path to generate left-handed or right-handed circularly polarized light; the control module switches the circular polarization chirality of the incident light by controlling the polarization state generation unit.

8. The multi-dimensional light field modulation system based on liquid crystal coherent pixels as described in claim 6, characterized in that, The light source and illumination module includes an angle adjustment unit for changing the angle of the incident light relative to the surface of the liquid crystal coherent pixel element; the control module controls the angle adjustment unit to change the incident angle.

9. The multi-dimensional light field modulation system based on liquid crystal coherent pixels as described in claim 6, characterized in that, The light source and illumination module includes a red laser (wavelength 632nm), a green laser (wavelength 532nm), and a blue laser (wavelength 473nm), as well as optical components for coupling the three laser beams to the same optical path at different preset off-axis angles.

10. The multi-dimensional light field manipulation system based on liquid crystal coherent pixels as described in claim 6, characterized in that, The imaging module includes an aperture stop for filtering out non-target diffraction order light.

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