A programmable wavefront detector based on a spatial light modulator

Abstract

This invention discloses a programmable wavefront detector based on a spatial light modulator, relating to the field of optical wavefront detection technology. It includes a spatial light modulator configured to load a programmable phase map onto its panel. The phase map comprises multiple arrayed lens phase mask units. This invention uses computer-controlled loading of the programmable phase map, enabling the spatial light modulator to change the focal length, aperture, and arrangement of the virtual lens array in real time—periodically uniform, non-periodically non-uniform, or distributed according to the incident light intensity. This allows for rapid adaptation to different detection scenarios without any mechanical movement, completely solving the problem of fixed parameters. Simultaneously, based on the light spot pattern fed back by the photodetector, the computer uses optimization algorithms such as random parallel gradient descent, simulated annealing, or neural networks to automatically generate a corrected phase map, repeatedly compensating for wavefront distortion until the residual wavefront aberration is less than a preset threshold.

Description

Technical Field

[0001] This invention relates to the field of optical wavefront detection technology, specifically to a programmable wavefront detector based on a spatial light modulator. Background Technology

[0002] With the rapid development of technologies such as adaptive optics, computational imaging, laser communication and precision measurement, wavefront detection, as a key link in realizing the acquisition of optical field phase information, directly affects the overall performance of the system through its detection accuracy and flexibility.

[0003] An existing patent (publication number: CN219244811U) provides a wavefront detector, which includes: a superlens array; the superlens array includes multiple superlenses arranged in an array; the superlenses include multiple nanostructures, and the superlenses are used to focus incident light. This wavefront detector not only has better wavefront detection performance due to its aberration-free focusing advantage, but also has advantages such as simple fabrication, low cost, and thin and light size.

[0004] However, the wavefront detectors using superlens arrays described above have the following drawbacks: First, once the superlens array is fabricated, its focal length, phase distribution, and operating mode are completely fixed, making it impossible to adjust in real time according to different incident light or detection requirements. If the detection sensitivity needs to be changed, it must be redesigned and fabricated, resulting in a long cycle and high cost. Second, the superlens array only acts as a passive focusing element and cannot perform active wavefront compensation for the incident light (such as applying specific spatial phase encoding or generating structured light), nor can it perform real-time verification and correction of the detection results, making it difficult to achieve closed-loop control. Third, the phase dispersion of superlenses is strong, and designs optimized for one wavelength show a significant performance degradation at another wavelength. Achieving wideband achromatic detection designs is complex and difficult, limiting its application in multi-wavelength or broadband light source scenarios. Finally, errors inevitably exist in the diameter, height, and period of the nanostructures during actual fabrication, introducing fixed aberrations that cannot be corrected during use, affecting detection accuracy.

[0005] To address these issues, we designed a programmable wavefront detector based on a spatial light modulator. Summary of the Invention

[0006] The purpose of this invention is to provide a programmable wavefront detector based on a spatial light modulator to solve the problems mentioned in the background art.

[0007] To address the aforementioned technical problems, this invention provides a programmable wavefront detector based on a spatial light modulator, comprising: a spatial light modulator configured to load a programmable phase map onto its panel, the phase map comprising multiple arrayed lens phase mask units, each lens phase mask unit being used to apply focused phase modulation to a corresponding sub-wavefront of the incident light wavefront to segment and converge the incident light wavefront into multiple focused spots; a photodetector disposed on the light-emitting side of the spatial light modulator, used to receive the transmitted multiple focused spots and generate corresponding electrical signals; and a computer connected to both the spatial light modulator and the photodetector, the computer being used to load the phase map onto the spatial light modulator and to receive and process the electrical signals generated by the photodetector to reconstruct the wavefront phase; wherein, the computer is further configured to: generate a corrected phase map based on the reconstructed wavefront phase, and superimpose the corrected phase map onto the lens phase mask units to compensate for the incident wavefront, and iteratively optimize through an optimization algorithm program until the residual wavefront aberration is less than a preset threshold.

[0008] Furthermore, the focal length, aperture, and array arrangement of the lens phase mask unit are dynamically configured in real time by the computer control; the array arrangement is one of periodic uniform arrangement, non-periodic non-uniform arrangement, or distributed arrangement according to the incident light intensity.

[0009] Furthermore, the computer includes an optimization algorithm program, which is used to iteratively optimize the parameters of the correction phase map based on the light intensity distribution pattern collected by the photodetector and a preset evaluation function.

[0010] Furthermore, the optimization strategy adopted by the optimization algorithm program is one of the following: stochastic parallel gradient descent algorithm, simulated annealing algorithm, or intelligent optimization algorithm based on neural network; the parameters of the corrected phase map are characterized by the coefficients of a multinomial Zernike polynomial.

[0011] Furthermore, the operating band of the spatial light modulator covers the visible light band and the near-infrared band.

[0012] Furthermore, the computer is also configured to superimpose vortex phase, random phase, or grating phase on the lens phase mask unit, so that the wavefront detector simultaneously possesses optical field encoding and mode decomposition functions.

[0013] Furthermore, the spatial light modulator is a transmissive liquid crystal spatial light modulator.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. By loading a programmable phase map via computer control, the spatial light modulator can change the focal length, aperture, and arrangement of the virtual lens array in real time—periodically uniform, non-periodically non-uniform, or distributed according to the incident light intensity. This allows for rapid adaptation to different detection scenarios without any mechanical movement, completely overcoming the shortcomings of fixed parameters. Simultaneously, based on the spot pattern fed back by the photodetector, the computer uses optimized algorithms such as random parallel gradient descent, simulated annealing, or neural networks to automatically generate a corrected phase map, repeatedly compensating for wavefront distortion until the residual wavefront aberration is less than a preset threshold. This adaptive closed-loop correction capability significantly improves the accuracy and environmental robustness of wavefront detection.

[0015] 2. By superimposing vortex phase, random phase, or grating phase onto the focusing phase, the wavefront detector simultaneously possesses optical field encoding and mode decomposition capabilities: superimposing vortex phase allows for the detection of the orbital angular momentum spectrum of incident light; superimposing random phase enables computational imaging or speckle encoding; and superimposing grating phase enables beam splitting and multi-field detection. This multi-functional integration upgrades the traditional wavefront detector into a "smart wavefront processor." Furthermore, by rapidly switching between different wavelength configuration tables, the spatial light modulator's operating band can cover visible light to near-infrared 400nm-2100nm, adapting to various wavelengths of incident light without requiring any hardware changes, effectively overcoming the problems of severe chromatic aberration and poor wide-band adaptability of superlenses. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the programmable wavefront detector of the spatial light modulator in this invention; Figure 2 This is a flowchart of the optimization algorithm for the liquid crystal spatial light modulator in this invention.

[0017] In the diagram: 1. Spatial light modulator; 2. Photodetector; 3. Computer. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Please see Figure 1-2This invention provides a technical solution: a programmable wavefront detector based on a spatial light modulator, comprising: a spatial light modulator 1, configured to load a programmable phase map on its panel, the phase map including multiple arrayed lens phase mask units, each lens phase mask unit being used to apply focused phase modulation to the corresponding sub-wavefront of the incident light wavefront, so as to divide and converge the incident light wavefront into multiple focused light spots; a photodetector 2, disposed on the light-emitting side of the spatial light modulator 1, used to receive the multiple focused light spots transmitted and generate corresponding electrical signals; a computer 3, connected to the spatial light modulator 1 and the photodetector 2 respectively, the computer 3 being used to load the phase map onto the spatial light modulator 1 and receive and process the electrical signals generated by the photodetector 2 to reconstruct the wavefront phase; wherein, the computer 3 is further configured to: generate a correction phase map according to the reconstructed wavefront phase, and superimpose the correction phase map onto the lens phase mask units to compensate for the incident wavefront, and iteratively optimize through an optimization algorithm program until the residual wavefront aberration is less than a preset threshold.

[0020] In this specific implementation, the spatial light modulator 1 is a transmissive liquid crystal spatial light modulator, whose panel can be loaded with a programmable phase map generated and transmitted by the computer 3. This phase map contains multiple arrayed lens phase mask units, each used to apply focused phase modulation to the corresponding sub-wavefront in the incident light wavefront, thereby splitting and converging the incident light wavefront into multiple focused spots. A photodetector 2 is located on the light-emitting side of the spatial light modulator 1, used to receive multiple focused spots and generate corresponding electrical signals. The computer 3 is connected to both the spatial light modulator 1 and the photodetector 2. The computer 3 loads the phase map into the spatial light modulator 1 and receives and processes the electrical signals generated by the photodetector 2 to reconstruct the wavefront phase. Based on this, the computer 3 generates a corrected phase map, i.e., a negative wavefront, according to the reconstructed wavefront phase, superimposes it onto the original lens phase mask units, and reloads it into the spatial light modulator 1 to actively compensate for the incident wavefront. Through multiple closed-loop iterations, until the residual wavefront aberration is less than a preset threshold, the reverse phase of the sum of the applied correction phases becomes the precise phase plane of the wavefront to be measured. This implementation method, through programmable phase maps and closed-loop iterative compensation, enables dynamic reconstruction of the virtual lens array without hardware replacement and real-time correction of wavefront distortion.

[0021] See Figure 1-2 The focal length, aperture, and array arrangement of the lens phase mask unit are dynamically configured in real time by computer control; the array arrangement can be one of periodic uniform arrangement, non-periodic non-uniform arrangement, or distributed arrangement according to the incident light intensity.

[0022] In specific implementation, based on the above technical solutions, this embodiment further limits the programmable dynamic configuration capability of the lens phase mask unit. The focal length, aperture, and array arrangement of the lens phase mask unit are dynamically configured in real time by computer 3. Specifically, computer 3 has multiple preset phase map generation algorithms, and users can adjust parameters on the software interface. Computer 3 then recalculates the phase distribution of each lens phase mask unit and loads it into spatial light modulator 1. The array arrangement can be a periodic uniform arrangement, an aperiodic non-uniform arrangement, or a distributed arrangement based on the incident light intensity. For example, when the incident light intensity has a Gaussian distribution, denser sub-apertures can be set in the central region and sparser sub-apertures in the edge region to improve the local resolution of wavefront reconstruction; or larger aperture units can be set in the weaker light region to improve the signal-to-noise ratio.

[0023] See Figure 1-2 Computer 3 includes an optimization algorithm program, which is used to iteratively optimize the parameters of the correction phase map based on the light intensity distribution pattern collected by photodetector 2 and the preset evaluation function.

[0024] In specific implementation, this embodiment further defines the functions of computer 3. Computer 3 includes an optimization algorithm program, which iteratively optimizes the parameters of the correction phase map based on the light intensity distribution pattern collected by photodetector 2 and a preset evaluation function. Specifically, in each closed-loop iteration, the program calculates the evaluation function value corresponding to the current residual wavefront, then adjusts the parameters of the correction phase map according to the optimization strategy, generates a new correction phase map, and superimposes it onto the lens phase mask unit. The light intensity pattern is collected again, and this process is repeated until the evaluation function meets the threshold requirement. Through this optimization algorithm program, this device achieves automated closed-loop control of wavefront detection and compensation.

[0025] See Figure 1-2 The optimization strategy adopted by the optimization algorithm program is one of the following: stochastic parallel gradient descent algorithm, simulated annealing algorithm, or intelligent optimization algorithm based on neural network; the parameters of the corrected phase map are characterized by the coefficients of a multinomial Zernike polynomial.

[0026] In specific implementation, this embodiment further defines the specific strategy employed by the optimization algorithm and the parameter form of the corrected phase diagram. The optimization strategy employed by the optimization algorithm is one of the following: Stochastic Parallel Gradient Descent (SPGD) algorithm, Simulated Annealing algorithm, or a neural network-based intelligent optimization algorithm. The parameters of the corrected phase diagram are represented by the coefficients of a multinomial Zernike polynomial. The wavefront is composed of a multinomial Zernike polynomial, and the optimization strategy optimizes the coefficients of each Zernike polynomial. In this embodiment, the optimization algorithm uses the Zernike coefficients as the optimization variable and the evaluation function as the objective function, employing an upper optimization strategy for iterative processing until convergence.

[0027] See Figure 1-2 The operating band of the spatial light modulator 1 covers the visible light band and the near-infrared band.

[0028] In specific implementation, this embodiment limits the operating wavelength range of the spatial light modulator 1. The operating wavelength of the spatial light modulator 1 covers the visible light band and the near-infrared band (400nm-2100nm). When switching the incident light wavelength, the computer 3 quickly switches between different wavelength configuration tables and recalculates the phase diagram, enabling the spatial light modulator 1 to quickly adapt to different wavelengths of incident light. This embodiment allows the same device to be used with multiple different wavelengths of incident light without the need for hardware replacement.

[0029] See Figure 1-2 The computer 3 is also configured to superimpose vortex phase, random phase or grating phase on the lens phase mask unit so that the wavefront detector can simultaneously have optical field encoding and mode decomposition functions.

[0030] In specific implementation, this embodiment further expands the phase map generation capability of the spatial light modulator 1. The computer 3 is also configured to superimpose vortex phase, random phase, or grating phase onto the lens phase mask unit. Specifically, when generating the phase map of the lens phase mask unit, the computer 3 adds the focused phase and the additional coded phase together to obtain a composite phase map, which is then loaded onto the spatial light modulator 1. After superimposing the vortex phase, the focused spot generated by each sub-aperture becomes a ring-shaped spot, which can simultaneously detect the wavefront and orbital angular momentum spectrum; superimposing the random phase can generate speckle illumination, suitable for wavefront coding in computational imaging; superimposing the grating phase can achieve beam splitting or deflection, which can be used to simultaneously detect multiple fields of view. This embodiment enables the wavefront detector to simultaneously possess optical field coding and mode decomposition functions, realizing multi-functional integrated detection.

[0031] See Figure 1-2 Spatial light modulator 1 is a transmissive liquid crystal spatial light modulator.

[0032] In specific implementation, this embodiment defines the specific type of spatial light modulator 1. The spatial light modulator 1 adopts a transmissive liquid crystal spatial light modulator, which works by utilizing the electrically controlled birefringence effect of liquid crystal molecules: the computer 3 applies different voltages to each pixel of the liquid crystal panel, which changes the orientation of the liquid crystal molecules in that pixel area, thereby producing a phase delay of 0 to 2π for the incident light transmitted through that pixel.

[0033] Please see Figure 2 The optimization algorithm process of this device includes the following steps: Program initialization: Computer 3 loads the initial array lens phase map into spatial light modulator 1. The initial phase map is generated based on the user-defined number of sub-apertures, focal length, and arrangement.

[0034] Data Acquisition 1: Photodetector 2 acquires multiple focused light spots of light intensity distribution pattern modulated by spatial light modulator 1, and transmits the pattern data to computer 3.

[0035] Wavefront reconstruction: Based on the acquired centroid offset of the light spot and the current system parameters, the computer restores the wavefront phase.

[0036] Negative wavefront loading: Based on the wavefront reconstruction results, computer 3 generates a negative wavefront, i.e., a corrected phase map, which is superimposed on the phase map of the array lens to form a new composite phase map, and then loaded into the spatial light modulator 1.

[0037] Data Acquisition 2: Photodetector 2 re-acquires the compensated light intensity distribution pattern.

[0038] Evaluation function calculation: Computer 3 calculates wavefront reconstruction quality indicators, including signal-to-noise ratio, phase flatness, and reconstruction error.

[0039] Optimization Judgment: If the evaluation function calculation result is higher than the preset threshold, for example, if the wavefront flatness is higher than the preset threshold, then adjust the negative wavefront parameters, i.e., the coefficients of each Zernike polynomial, according to the optimization strategy, and then return to the "negative wavefront loading" step to repeat the process; if the evaluation function calculation result is lower than or equal to the preset threshold, for example, if the wavefront flatness is lower than the preset threshold, then the compensation is determined to be complete. At this time, the inversion of the loaded negative phase is the current wavefront result. Computer 3 saves the wavefront data and the program ends.

[0040] Working principle: The incident light beam directly illuminates the panel of the spatial light modulator 1. The spatial light modulator 1 is a transmissive liquid crystal spatial light modulator, and its panel is loaded with a programmable phase map generated in real time by the computer 3. This phase map contains multiple arrayed lens phase mask units, each unit applying focused phase modulation to the corresponding sub-wavefront in the incident wavefront, thereby dividing and converging the entire wavefront into multiple focused light spots, forming an equivalent virtual lens array; The emitted focused light spot is received by a photodetector 2 located on the light-emitting side and converted into an electrical signal, which is then transmitted to a computer 3. The computer 3 first uses a wavefront reconstruction algorithm to reconstruct the phase distribution of the incident wavefront based on the acquired centroid offset of the light spot and the current system parameters. Subsequently, the computer 3 generates a corrected phase map, i.e., a negative wavefront, based on the reconstruction results, and superimposes it onto the original lens phase mask unit to form a new composite phase map, which is then reloaded onto the spatial light modulator 1 to achieve active compensation for wavefront distortion. The "detection, reconstruction, and compensation" process constitutes a closed-loop iteration. After each iteration, computer 3 calculates evaluation functions such as signal-to-noise ratio and phase flatness through an optimization algorithm program, and adjusts the parameters of the corrected phase map, i.e., the coefficients of each Zernike polynomial, according to optimization strategies such as stochastic parallel gradient descent, simulated annealing, or neural networks, until the residual wavefront aberration is less than a preset threshold. At this point, the reverse phase of the loaded total corrected phase is the accurate phase surface of the wavefront to be measured, which is output and saved by computer 3. Throughout the process, the focal length, aperture, and arrangement of the lens phase mask units can be dynamically configured in real time via computer control, and vortex phases, random phases, or grating phases can be superimposed to achieve optical field encoding and mode decomposition. Simultaneously, different wavelengths from the visible to near-infrared bands can be quickly adapted by switching the wavelength configuration table.

Claims

1. A programmable wavefront detector based on a spatial light modulator, characterized in that, include: A spatial light modulator (1) is configured to load a programmable phase map on its panel, the phase map comprising a plurality of arrayed lens phase mask units, each lens phase mask unit being used to apply focused phase modulation to a corresponding sub-wavefront of the incident light wavefront, so as to divide and converge the incident light wavefront into a plurality of focused light spots. A photodetector (2) is disposed on the light-emitting side of the spatial light modulator (1) for receiving the multiple focused light spots transmitted out and generating corresponding electrical signals. Computer (3) is connected to the spatial light modulator (1) and the photodetector (2) respectively. Computer (3) is used to load phase map into the spatial light modulator (1) and receive and process the electrical signal generated by the photodetector (2) to reconstruct wavefront phase. The computer (3) is further configured to: generate a corrected phase map based on the reconstructed wavefront phase, and superimpose the corrected phase map onto the lens phase mask unit to compensate for the incident wavefront, and iteratively optimize the algorithm program until the residual wavefront aberration is less than a preset threshold.

2. The programmable wavefront detector based on a spatial light modulator as described in claim 1, characterized in that: The focal length, aperture, and array arrangement of the lens phase mask unit are dynamically configured in real time by the computer (3); the array arrangement is one of periodic uniform arrangement, non-periodic non-uniform arrangement, or distributed arrangement according to the incident light intensity.

3. A programmable wavefront detector based on a spatial light modulator as described in claim 1, characterized in that: The computer (3) includes an optimization algorithm program, which is used to iteratively optimize the parameters of the correction phase map based on the light intensity distribution pattern collected by the photodetector (2) and a preset evaluation function.

4. A programmable wavefront detector based on a spatial light modulator as described in claim 3, characterized in that: The optimization algorithm program employs one of the following optimization strategies: stochastic parallel gradient descent algorithm, simulated annealing algorithm, or intelligent optimization algorithm based on neural network; the parameters of the corrected phase map are characterized by the coefficients of a multinomial Zernike polynomial.

5. A programmable wavefront detector based on a spatial light modulator as described in claim 1, characterized in that: The spatial light modulator (1) operates in the visible light band and the near-infrared band.

6. A programmable wavefront detector based on a spatial light modulator as described in claim 1, characterized in that: The computer (3) is also configured to superimpose a vortex phase, a random phase, or a grating phase on the lens phase mask unit so that the wavefront detector can simultaneously have optical field encoding and mode decomposition functions.

7. A programmable wavefront detector based on a spatial light modulator as described in claim 1, characterized in that: The spatial light modulator (1) is a transmissive liquid crystal spatial light modulator.

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