CN-121994364-A - Few-pixel wavefront sensing device and method

CN121994364ACN 121994364 ACN121994364 ACN 121994364ACN-121994364-A

Abstract

The invention relates to the intersection field of wavefront sensing and computational imaging, the existing imaging technology has the advantages of wide spectral response range and single photon magnitude, but the technology is difficult to be applied to high-speed real-time imaging scenes due to the dependence on a continuous and repeated spatial modulation mechanism, the invention provides a few-pixel wavefront sensing device and a method, the low-pixel wavefront sensing device based on the coded grating and the lens array efficiently and quickly acquires the space wavefront information by using the low-pixel detector, and the space is divided and the subspaces are sampled, so that the parallel acquisition of data is realized while the required space coding mode is reduced, the problems of high cost and difficult acquisition of the special-band array detector are avoided, the detection efficiency under the low-light condition is improved, and the spectrum range of the wavefront sensing is expanded.

Inventors

ZHAI AIPING
JIAO XUANHE
ZHENG TINGTING
ZHAO WENJING
WANG DONG

Assignees

太原理工大学

Dates

Publication Date: 20260508
Application Date: 20260210

Claims (7)

1. The low-pixel wavefront sensing device based on the coded grating is characterized by comprising a 4f lens group (1), a spatial light modulator (2), a focusing lens (4), a pinhole group (5) and a low-pixel detector (6), wherein the 4f lens group (1) and the spatial light modulator (2) are sequentially arranged along the transmission direction of a target space wavefront to be detected, the focusing lens (4) and the pinhole group (5) are arranged between the spatial light modulator (2) and the low-pixel detector (6) for receiving a modulated light beam, the spatial light modulator (2) is divided into n subspaces, the number of units of the low-pixel detector (6) is n, the directions of the n subspace gratings are d1, d2, the period is k1, k2. and kn.
2. The method for sensing the low-pixel wavefront based on the coded grating is realized by the device for sensing the low-pixel wavefront based on the coded grating according to claim 1, and is characterized in that after a light beam of a target space wavefront to be detected, which is modulated by a spatial light modulator (2), is focused and filtered, the light intensity is detected and recorded by a low-pixel detector (6), each subspace wavefront is reconstructed according to the light intensity and a first space coding mode (3), and n subspace wavefronts are synthesized into a complete target space wavefront, and the method comprises the following specific steps: Step A1, constructing a few-pixel wavefront sensing device based on an encoded grating, selecting a spatial encoding mode loaded on a spatial light modulator (2), wherein a first spatial encoding mode (3) is formed by overlapping a reference mode, a spatial base mode and oblique grating modes in different directions and periods, and the imaging resolution M of a target spatial wavefront to be detected N, the spatial light modulator (2) is divided into N subspaces, each subspace corresponds to a spatial coding mode, and the number of units of the few-pixel detector (6) is N; A2, the target space wave front to be measured is relayed to the surface of the space light modulator (2) after passing through the 4f lens group (1), the surface of the space light modulator displays a first space coding mode (3) after coding the grating, and the space resolution of the space coding mode corresponding to each subspace wave front is (M/n) (N/N), N subspace coding modes are combined; A3, dividing a reference light field and a signal light field by the light beam modulated in the step A2 according to the current space coding mode, and dividing the reference light field and the signal light field by an inclined grating to form a plurality of subspace wave fronts of independent interference; A4, focusing the subspace wave front in the step A3 by a focusing lens (4) and performing Fourier transformation to form diffraction orders, calculating the distance between the corresponding diffraction orders of each subspace according to different periods and directions of the inclined grating and a grating diffraction distance formula, and adjusting the positions of n pinholes of a pinhole group (5) according to the distance between the corresponding diffraction orders, wherein the pinhole group (5) finishes filtering and diffraction order screening of light beams; A5, detecting and recording light intensity of the diffraction order light beams screened by the pinhole group (5) through the small-pixel detector (6), detecting and recording the diffraction order light beams corresponding to each subspace through the unit corresponding to one small-pixel detector (6) after screening the corresponding pinholes, and reconstructing each subspace wavefront according to the recorded light intensity and the spatial coding mode by calculation, wherein n subspace wavefronts are synthesized into a complete target space wavefront.
3. The lens array-based low-pixel wavefront sensing device is characterized by comprising a 4f lens array group (7), a spatial light modulator (2), a lens array (8), a pinhole group (5) and a low-pixel detector (6), wherein the 4f lens array group (7) and the spatial light modulator (2) are sequentially arranged along the transmission direction of a target space wavefront to be detected, the lens array (8) and the pinhole group (5) are arranged between the spatial light modulator (2) and the low-pixel detector (6) for receiving modulated light beams, the spatial light modulator is divided into n subspaces, and the number of units of the low-pixel detector (6) is n.
4. A lens array-based low-pixel wavefront sensing method implemented by the lens array-based low-pixel wavefront sensing device of claim 3, comprising the steps of: Step B1, constructing a lens array-based few-pixel wavefront sensing device, selecting a second spatial coding mode (9) loaded on the spatial light modulator (2), wherein the spatial coding mode is formed by overlapping a reference mode and a spatial base mode, and the imaging resolution M of a target spatial wavefront to be detected N, the spatial light modulator (2) is divided into N subspaces, the number of units of the small pixel detector (6) is N, and the spatial resolution of the spatial coding mode corresponding to each subspace wavefront is (M/N) (N/n); B2, vertically guiding the wavefront to be measured to a corresponding subarea of the surface of the spatial light modulator (2) through a 4f lens array group (7), loading and switching a second spatial coding mode (9) on the spatial light modulator (2) to modulate, and combining n subspace coding modes, wherein the second spatial coding mode (9) of each subarea comprises the same reference light field and the same signal light field; B3, the light beams modulated by the spatial light modulator (2) are irradiated to the lens array (8) as parallel light beams, the light beams are focused by focusing sub-lenses corresponding to the lens array (8) and are subjected to Fourier transform, so that different subspace wave fronts are interfered independently, the positions of n pinholes of the pinhole group (5) are adjusted according to the positions of diffraction orders after Fourier transform of the sub-lenses in the lens array (8), and the pinhole group (5) finishes filtering and diffraction order screening of the light beams; and step B5., detecting and recording light intensity of the diffraction order light beams screened by the pinhole group (5) by a few-pixel detector (6), detecting and recording the diffraction order light beams corresponding to each subspace by a unit of one few-pixel detector (6), reconstructing each subspace wavefront by operation according to the light intensity value and the space coding mode, and synthesizing n subspace wavefronts into a complete target space wavefront.
5. The method according to claim 2 or claim 4, wherein the reference mode is an interference occurring in a subspace, the reference mode is any one of a checkerboard reference mode, an internal and external reference mode or a self-reference mode, the spatial base mode is used for spatial wavefront sampling, and the spatial base mode is any one of a hadamard mode, a fourier mode, a discrete cosine mode or a cyclic hadamard mode.
6. A method of low pixel wavefront sensing according to claim 2 or claim 4, wherein the interference is in the form of phase shifting interference and off-axis interference.
7. The low pixel wavefront sensing method of claim 2, wherein the tilted grating pattern distinguishes interference information of different subspace wavefronts in the fourier domain.

Description

Few-pixel wavefront sensing device and method Technical Field The invention relates to the field of wavefront sensing and computational imaging intersection, in particular to a few-pixel wavefront sensing device and a method. Background The curved surface formed by the equiphase surfaces of waves propagating to a certain position is called a wave front, and the points at the forefront of the waves at a certain moment are connected. The vibration of the wavefront particles is the same as the initial vibration of the source of the mechanical wave. The wavefront measurement technology is an optical detection method for accurately analyzing the phase distribution and distortion of light waves, and the core principle is that the sensor captures the wavefront inclination or phase difference, so as to reconstruct the wavefront morphology ‌. The existing wavefront measurement technology is mainly realized by a high-density CCD/COMS area array detector, and the amplitude and the phase of the spatial wavefront can be calculated pixel by combining methods such as interferometry. Because of the detection requirements of some special wave bands, such as infrared, ultraviolet and terahertz, the area array detector is not easy to obtain due to the complex manufacturing process. On the other hand, in low-light detection situations, the number of photons received by the tiny unit pixels (cells) is greatly reduced, so that imaging is not possible. In response to these deficiencies, emerging techniques utilize single-pixel detectors to reconstruct a spatial wavefront, known as single-pixel wavefront imaging techniques. The single-pixel wavefront imaging technology is a novel optical measurement method based on the cooperative work of a single-pixel detector and a spatial light modulator, and high-precision detection of wavefront phase distribution is realized through compressed sensing and computational reconstruction. The technology samples the space wavefront and uses a single pixel detector to acquire a time-varying interference light intensity signal, and finally utilizes a reconstruction algorithm to calculate the space wavefront, compared with the traditional imaging technology, the technology has the advantages of wide spectral response range and single photon magnitude, but the technology is difficult to apply in a high-speed real-time imaging scene due to the dependence on a continuous and multiple spatial modulation mechanism, and the development and application of the technology are restricted. Disclosure of Invention Aiming at the defects existing in the prior art, the invention aims to provide a low-pixel wavefront sensing device and a method, which can utilize a method for efficiently and rapidly acquiring space wavefront information by a low-pixel detector, avoid dependence on a high-density area array detector, and obviously improve the speed of a wavefront imaging technology at the same time, so that the low-pixel wavefront sensing is suitable for a real-time imaging scene. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: A low-pixel wavefront sensing device based on a coded grating comprises a 4f lens group, a spatial light modulator, a focusing lens, a pinhole group and a low-pixel detector, wherein the 4f lens group and the spatial light modulator are sequentially arranged along the transmission direction of a target space wavefront to be detected, the focusing lens and the pinhole group are arranged between the spatial light modulator and the low-pixel detector for receiving a modulated light beam, the spatial light modulator is divided into n subspaces, the number of units of the low-pixel detector is n, the directions of the n subspace gratings are d1, d2, dn, and the period is k1, k2.. The method is realized by the code grating-based low-pixel wavefront sensing device, light beams modulated by a spatial light modulator on target space wavefront to be detected are focused on the light beams after filtering, light intensity is detected and recorded by a low-pixel detector, each subspace wavefront is reconstructed according to the light intensity and a first space coding mode, and n subspace wavefronts are synthesized into a complete target space wavefront, and the method comprises the following specific steps: Step A1, constructing a few-pixel wavefront sensing device based on an encoded grating, selecting a spatial encoding mode loaded on a spatial light modulator, wherein the first spatial encoding mode is formed by overlapping a reference mode, a spatial base mode and oblique grating modes in different directions and periods, and the imaging resolution M of a target spatial wavefront to be detected N, the spatial light modulator is divided into N subspaces, each subspace corresponds to a spatial coding mode, and the number of units of the fewer-pixel detector is N; A2, the target space wave front to be measured is relayed to the surface of the space l