Imaging method for realizing single-pixel holographic imaging based on cyclic matrix modulation

Abstract

The invention relates to the crossing field of computer-generated holography and single-pixel imaging. The invention discloses a method for realizing single-pixel holographic imaging based on cyclic matrix modulation, which comprises the following steps of: selecting a used cyclic modulation mode generation module, selecting coaxial interference imaging or off-axis interference imaging, determining initial imaging conditions and parameters; the initial conditions and parameters comprise the wavefront imaging resolution M * N to be measured and the parameters of the cyclic modulation mode generation module; determining a cyclic modulation mode loaded on the cyclic modulation mode generation module; building a device for realizing single-pixel holographic imaging based on cyclic matrix modulation according to the selected cyclic modulation mode generation module, and determining the aperture r of a pinhole; a modulation mode is loaded on the cyclic modulation mode generation module, and meanwhile, a single-pixel detector collects a Fourier plane center point signal intensity value corresponding to each modulation mode; and reconstructing the target space wavefront.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of computational holography and single-pixel imaging. BACKGROUND

[0002] Single-pixel holographic imaging is a kind of computational imaging method combining single-pixel detector and holographic technology. By projecting the coded pattern through the spatial light modulator, the light intensity information is collected by the single-point detector, and the complex amplitude distribution (amplitude and phase) of the object is reconstructed by combining the compression sensing algorithm. Its core advantage is to break through the limitation of traditional area array detector, suitable for special light band, weak light and other scenes, and significantly reduce the hardware cost. By modulating the structured light field to the target through the modulator, the single-pixel detector records the light intensity response, and the image is reconstructed by using the mathematical inner product relationship. Single-pixel imaging technology has the advantages of wide spectral response rate, high detection sensitivity and accurate time resolution. When single-pixel imaging technology is combined with interference, the spatial wavefront information can be further detected by the single-pixel detector, and single-pixel holographic imaging is realized. Single-pixel holographic imaging technology has been widely used in biomedical microscopes, quantum imaging, single-photon imaging and other fields. In single-pixel holographic imaging, light field modulation is essential. Most of the current mainstream light field modulation schemes use liquid crystal spatial light modulators (LC-SLM) or digital micro-mirror devices (DMD), which use the switching of the modulation pattern to realize the dynamic transformation of the structured light field in space. This process is generally achieved by loading Hadamard modulation bases, Fourier modulation bases, etc. on the modulation device, and switching the modulation pattern. For these light field modulation schemes, on the one hand, the traditional modulation pattern needs to be completely changed each time to get the next new modulation pattern, which produces a large amount of pattern data, greatly increasing the pressure on the modulation device hardware memory, thereby unable to realize full-sampling high-resolution imaging; on the other hand, whether it is LC-SLM or DMD, the refresh rate of the circuit hardware limits the imaging frame rate of the imaging system, making it difficult for single-pixel imaging to be applied to dynamic or real-time imaging. SUMMARY

[0003] The purpose of the present application is to realize a device and method for fast single-pixel holographic imaging by using a circulant matrix. By using the movable circulant modulation pattern generated by the circulant matrix to replace the traditional modulation pattern, a new modulation pattern can be obtained by moving only one column each time, which greatly saves the storage space of the digital micro-mirror device (DMD) occupied by the modulation pattern.

[0004] There are three kinds of implementation schemes for the method of using cyclic modulation pattern for fast single-pixel holographic imaging. The first kind is to shift and display the generated cyclic modulation pattern through a DMD. By using the region of interest (ROI) function of the DMD, the refresh rate of the DMD can be improved by controlling the number of rows of the movable micromirrors of the DMD; combined with the rolling expansion function, each modulation pattern is displayed on the ROI in turn to realize the switching of the modulation light field. The second kind is to use a single fixed ring-shaped mask to replace the traditional spatial light modulator, and map the cyclic modulation pattern onto the ring-shaped mask. By periodically rotating the ring-shaped mask, different modulation patterns can be used to periodically modulate the target. The third kind is to use a rotating polygon mirror combined with a DMD to divide the cyclic modulation pattern into several blocks and display them on the DMD in turn. By using the high-speed horizontal scanning of the rotating polygon mirror, different spatial modulation patterns can be used to periodically modulate the target at a high speed. This method not only greatly improves the imaging speed, but also retains the high pixel number and flexibility of using a DMD to display the modulation pattern.

[0005] The technical scheme adopted by the present application is: a method for realizing single-pixel holographic imaging based on cyclic matrix modulation, which is performed according to the following steps Step one, select the cyclic modulation pattern generation module to be used, select coaxial interferometric imaging or off-axis interferometric imaging, and determine the initial conditions and parameters of imaging, including: the imaging resolution of the wavefront to be measured MxN and the parameters of the cyclic modulation pattern generation module; Step two, determine the cyclic modulation pattern loaded on the cyclic modulation pattern generation module. If it is coaxial interferometric imaging, the cyclic modulation pattern is a combination of a reference pattern, a cyclic modulation base pattern and a phase shift pattern superimposed together. If it is off-axis interferometric imaging, the rectangular cyclic modulation pattern is a combination of a reference pattern, a cyclic modulation base pattern and a tilted phase grating superimposed together. The reference pattern is used to divide the incident wavefront into reference and signal parts, and the spatial resolution of the reference pattern is consistent with that of the cyclic modulation base pattern. The cyclic modulation base pattern is used to sample the introduced wavefront in the signal part. The phase shift pattern is used to introduce a fixed phase difference between the reference beam and the signal beam. The tilted phase grating is used to introduce an off-axis angle between the reference beam and the signal beam to produce a linear phase difference; Step three, according to the selected cyclic modulation pattern generation module, build a device for realizing single-pixel holographic imaging based on cyclic matrix modulation, and determine the aperture r of the pinhole, r≤1.22λƒ / d, wherein λ is the wavelength of the light beam incident to the focusing lens, ƒ is the focal length of the focusing lens, and d is the diameter of the light beam incident to the focusing lens; Step four, load the modulation pattern on the cyclic modulation pattern generation module, and simultaneously collect the Fourier plane center point signal intensity value corresponding to each modulation pattern by the single-pixel detector. Step five, reconstructing the target spatial wavefront: for on-axis interferometric imaging, the complex coefficient spectrum of the target spatial wavefront is obtained according to the phase-shifting technique, and the single-pixel reconstruction algorithm is used to recover the target spatial wavefront; for off-axis interferometric imaging, the off-axis hologram of the target is first reconstructed by using the single-pixel reconstruction algorithm, and then the Fourier fringe analysis method is used to recover the spatial wavefront of the target object according to the obtained off-axis hologram of the target, and the amplitude and phase of the target spatial wavefront are obtained.

[0006] The cyclic modulation basis mode is one of a cyclic S matrix basis mode, a Bernoulli matrix basis mode, a sparse random matrix basis mode, a Toeplitz matrix basis mode and a generalized cyclic matrix basis mode; the reference mode pattern is one of a checkerboard reference mode pattern, an external reference mode pattern and a random reference mode pattern; the complex field modulation method is a Lee method or a superpixel method; and the single-pixel reconstruction algorithm is a second-order correlation reconstruction algorithm or a compressed sensing reconstruction algorithm.

[0007] The device used by the method for realizing single-pixel holographic imaging based on a cyclic matrix modulation comprises a rectangular cyclic modulation pattern generation module, a pinhole (5), a focusing lens (4) and a single-pixel detector (6), the pinhole (5) is arranged at a back focal point of the focusing lens (4), when a wave front to be measured passes through the rectangular cyclic modulation pattern generation module, the rectangular cyclic modulation pattern generation module modulates the wave front to be measured periodically, the single-pixel detector (6) collects a signal intensity value of a center point of a Fourier plane after modulation by the rectangular cyclic modulation pattern generation module, and then reconstructs a target space wave front; the rectangular cyclic modulation pattern generation module is one of a single-pixel holographic imaging device based on a DMD, a single-pixel fast holographic imaging device based on a ring-shaped mask and a single-pixel fast holographic imaging device based on a rotating polygon mirror combined with a DMD; the single-pixel holographic imaging device based on the DMD comprises a first lens (1), a second lens (2) and a digital micro-mirror device (3), the first lens (1) and the second lens (2) are coaxially arranged with the digital micro-mirror device (3), the digital micro-mirror device (3) is arranged at a horizontal focal length of the second lens (2), the first lens (1) and the second lens (2) constitute a 4-f system, a wave front to be measured is modulated by the digital micro-mirror device (3) after passing through the 4-f system, the modulated light beam is detected by the single-pixel detector (6) after passing through the focusing lens (4) and the pinhole (5) to obtain a signal intensity value of a center point of a Fourier plane.The device for single-pixel fast holographic imaging based on ring-shaped mask includes a ring-shaped mask transmission device and a ring-shaped mask reflection device, the ring-shaped mask transmission device includes a first lens (1), a second lens (2) and a transmission ring-shaped mask (13), the first lens (1), the second lens (2), the transmission ring-shaped mask (13), a focusing lens (4) are sequentially arranged, the first lens (1) and the second lens (2) constitute a 4-f system, the transmission ring-shaped mask (13) is located at the horizontal focal length of the second lens (2), a wavefront to be measured is irradiated to the transmission ring-shaped mask (13) through the 4-f system, the light beam transmitted by the transmission ring-shaped mask (13) is detected by a single-pixel detector (6) after passing through the focusing lens (4) and a pinhole (5) to obtain a signal intensity value of a center point of a Fourier plane, the ring-shaped mask reflection device includes a first lens (1), a second lens (2), a reflection ring-shaped mask (14) and a cubic beam splitter (7), the first lens (1), the second lens (2), the cubic beam splitter (7) and the reflection ring-shaped mask (14) are sequentially arranged, the line connecting the cubic beam splitter (7) and the focusing lens (4) is perpendicular to the line connecting the first lens (1) and the second lens (2), a wavefront to be measured is split by the cubic beam splitter (7), one beam is irradiated to the reflection ring-shaped mask (14) and the other beam is irradiated to the focusing lens (4), the wavefront to be measured is split into two beams of light after being irradiated to the cubic beam splitter (7) through the 4-f system, one beam of light is irradiated to the reflection ring-shaped mask (14) and is reflected back to the cubic beam splitter (7) by the original route, and then is reflected back to the focusing lens (4) and the pinhole (5) and is detected by the single-pixel detector (6) to obtain a signal intensity value of a center point of a Fourier plane.The device for single-pixel fast holographic imaging based on a rotating polygon mirror combined with a DMD comprises a first lens (1), a second lens (2), a third lens (15), a fourth lens (8), a fifth lens (9), a rotating polygon mirror (11), a first mirror (10), a second mirror (12), and a digital micromirror device (3). The digital micromirror device (3) is placed at the back focal point of the first lens (1). The second lens (2) and the third lens (15) form a 4-f system. The line connecting the second lens (2) and the third lens (15) is perpendicular to the axis of the first lens (1). The second mirror (12) is located on the reflected light beam of the first mirror (10). The wavefront to be measured is irradiated to the rotating polygon mirror (11) to occur the first reflection. The reflected light beam of the rotating polygon mirror (11) enters the second lens (2) and the third lens (15). The light beam emitted from the third lens (15) is reflected to the second mirror (12) by the first mirror (10). The reflected light beam of the second mirror (12) enters the digital micromirror device (3) for modulation. The light beam modulated by the digital micromirror device (3) is irradiated to the rotating polygon mirror (11) to occur the second reflection. The reflected light beam of the rotating polygon mirror (11) is reflected to the fifth lens (9) and the focusing lens (4). The light beam passing through the focusing lens (4) is detected by the single-pixel detector (6) after passing through the pinhole (5) to obtain the signal intensity value of the Fourier plane center point.

[0008] When the selected cyclic modulation pattern generation module is implemented based on a DMD, coaxial interference imaging is selected, and the following steps are performed Step one, when the selected cyclic modulation pattern generation module is implemented based on a DMD, coaxial interference imaging is selected, and initial conditions and parameters for imaging are determined. The initial conditions and parameters include the imaging resolution M×N of the wavefront to be measured, the number of steps for phase shifting, and the size of the ROI region on the digital micromirror device (3). Step two, the cyclic modulation pattern loaded on the digital micromirror device (3) is determined. The cyclic modulation pattern is a binary pattern loaded on the digital micromirror device (3). The cyclic modulation pattern is a reference mode pattern, a cyclic modulation base pattern, and a phase shifting pattern combined and superimposed based on a complex field modulation method. The cyclic modulation base pattern generation process is as follows: a double prime number method is used to generate a cyclic base matrix of M×N order. Each row of the cyclic base matrix is reshaped into a submatrix of M×N size. Each submatrix is sequentially spliced into a rectangular cyclic matrix base pattern of M×(M×N+N-1). Based on the complex field modulation method, the complex field of the rectangular cyclic modulation pattern is converted into a binary pattern that can be directly loaded on the DMD. Step three, build a single-pixel holographic imaging device based on DMD, the target spatial wave front is introduced into the surface of digital micromirror device (3) by 4-f system vertical illumination, the aperture r of pinhole is determined, r≤1.22λƒ / d, wherein, λ is the wavelength of the incident beam to the focusing lens, ƒ is the focal length of the focusing lens, d is the diameter of the incident beam to the focusing lens; Step four, load a rectangular cyclic modulation pattern on the digital micromirror device (3), set the ROI size on the digital micromirror device (3) according to the imaging resolution, the number of activated rows is N, the rolling start row of the rolling program is set to the starting row of the rectangular cyclic modulation pattern, the rolling end row is set to the termination row of the rectangular cyclic modulation pattern, and the rolling step is set to one imaging pixel at a time. Each rolling modulation pattern modulates the target in turn, while the single-pixel detector collects the Fourier plane center point signal intensity value corresponding to each rolling modulation pattern; Step five, reconstruct the target spatial wave front: obtain the complex coefficient spectrum of the target spatial wave front according to the phase shift technique, and recover the target spatial wave front using the single-pixel reconstruction algorithm.

[0009] When the rectangular cyclic modulation pattern generation module selected for use is implemented based on DMD, off-axis interference imaging is selected, and the following steps are performed Step one, when the rectangular cyclic modulation pattern generation module selected for use is implemented based on DMD, off-axis interference imaging is selected, and the initial conditions and parameters include: the imaging resolution M×N of the wave front to be measured, the off-axis angle θ of the signal light relative to the reference light, i.e. the number of periods of the tilted phase grating, and the ROI size on the digital micromirror device (3); Step two, determine the rectangular cyclic modulation pattern loaded on the digital micromirror device (3), the rectangular cyclic modulation pattern is a combination of a reference mode pattern, a cyclic modulation base matrix, and a tilted phase grating superimposed together, the cyclic modulation base matrix generation process is: generating an M×N order cyclic base matrix using the double prime number method, reshaping each row of the cyclic base matrix into an M×N size submatrix, then sequentially splicing each submatrix into an M×(M×N+N-1) rectangular cyclic modulation pattern, based on the complex field modulation method, converting the complex value cyclic modulation pattern into a binary pattern that can be directly loaded on the DMD; Step three, build a single-pixel holographic imaging device based on DMD, the target spatial wave front is introduced into the surface of digital micromirror device (3) by 4-f system vertical illumination, the aperture r of pinhole is determined, r≤1.22λƒ / d, wherein, λ is the wavelength of the incident beam to the focusing lens, ƒ is the focal length of the focusing lens, d is the diameter of the incident beam to the focusing lens; Step four, load a rectangular cyclic modulation pattern on the digital micromirror device (3), set the ROI size on the digital micromirror device (3) according to the imaging resolution, the number of activated rows is N, the rolling start row of the rolling program is set as the start row of the rectangular cyclic modulation pattern, the rolling end row is set as the end row of the rectangular cyclic modulation pattern, and the rolling step is set as one imaging pixel each time. Each rolling modulation pattern modulates the target in turn, and the single-pixel detector collects the Fourier plane center point signal intensity value corresponding to each rolling modulation pattern; Step five, reconstructing the target spatial wave front: first, according to the coefficient spectrum composed of the Fourier plane center point signal intensity values obtained by the single-pixel detector, the off-axis hologram of the target is reconstructed by using the single-pixel reconstruction algorithm, and then the spatial wave front of the target object is recovered by using the Fourier fringe analysis method according to the obtained off-axis hologram of the target, and the amplitude and phase of the target spatial wave front are obtained.

[0010] When the rectangular cyclic modulation pattern generation module based on the ring-shaped mask is selected to be implemented, the on-axis interference imaging is selected, and the following steps are performed Step one, when the rectangular cyclic modulation pattern generation module based on the ring-shaped mask is selected to be implemented, the on-axis interference imaging is selected, and the initial conditions and parameters are determined, including: the imaging resolution MxN of the to-be-measured wave front, the number of multi-step phase shifts, the size of a single pixel mapped on the ring-shaped mask, and the rotating speed of the ring-shaped mask motor. Step two, determine the rectangular cyclic modulation pattern mapped on the ring-shaped mask, the rectangular cyclic modulation pattern is a binary pattern mapped on the ring-shaped mask, and the rectangular cyclic modulation pattern is a reference mode pattern, a cyclic modulation base pattern and a phase shift pattern combined and superimposed based on a complex field modulation method, Step three, build a single-pixel fast holographic imaging device based on the ring-shaped mask, introduce the target spatial wave front into the acting surface of the ring-shaped mask through the 4-f system vertical illumination, the ring-shaped mask is a transmission ring-shaped mask (13) or a reflection ring-shaped mask (14), determine the aperture r of the pinhole, r≤1.22λƒ / d, wherein λ is the wavelength of the light beam incident to the focusing lens, ƒ is the focal length of the focusing lens, and d is the diameter of the light beam incident to the focusing lens; Step four, etch the ring-shaped mask of the modulation pattern, start rotating by applying a pulse signal to the motor, and interfere after modulating the incident light, while the single-pixel detector collects the Fourier plane center point signal intensity value corresponding to each modulation pattern; Step five, reconstruct the target spatial wave front: obtain the complex coefficient spectrum of the target spatial wave front according to the phase shift technology, and recover the target spatial wave front by using the single-pixel reconstruction algorithm.

[0011] When the rectangular cyclic modulation pattern generation module selected for use is implemented based on a ring-shaped mask, off-axis interference imaging is selected, and the following steps are performed Step one, when the rectangular cyclic modulation pattern generation module selected for use is implemented based on a ring-shaped mask, off-axis interference imaging is selected, initial conditions and parameters for imaging are determined, and the initial conditions and parameters include: imaging resolution MxN of a wavefront to be measured, size of a single pixel mapped on the ring-shaped mask, number of periods of a tilted phase grating, i.e., off-axis angle θ of signal light relative to reference light, and rotation speed of a ring-shaped mask motor Step two, a rectangular cyclic modulation pattern mapped on the ring-shaped mask is determined, the rectangular cyclic modulation pattern is a binary pattern mapped on the ring-shaped mask, and the rectangular cyclic modulation pattern is a reference mode pattern, a cyclic modulation base pattern, and a tilted phase grating combined and superimposed based on a complex field modulation method Step three, a device for single-pixel fast holographic imaging based on a ring-shaped mask is built, a target spatial wavefront is introduced into an action surface of the ring-shaped mask through 4-f system vertical illumination, the ring-shaped mask is a transmission ring-shaped mask (13) or a reflection ring-shaped mask (14), an aperture r of a pinhole is determined, r≤1.22λƒ / d, where λ is a wavelength of light incident on a focusing lens, ƒ is a focal length of the focusing lens, and d is a diameter of light incident on the focusing lens Step four, the ring-shaped mask etched with the modulation pattern starts to rotate by applying a pulse signal to the motor, and after the incident light is modulated, interference occurs, and a single-pixel detector collects a signal intensity value of a center point of a Fourier plane corresponding to each modulation pattern Step five, reconstructing the target spatial wavefront: first, a coefficient spectrum composed of signal intensity values of the center point of the Fourier plane obtained by the single-pixel detector is used to reconstruct a target off-axis hologram by using a single-pixel reconstruction algorithm, and then the spatial wavefront of the target object is recovered by using Fourier fringe analysis method according to the obtained target off-axis hologram, and the amplitude and phase of the target spatial wavefront are obtained

[0012] When the cyclic modulation pattern generation module selected for use is implemented based on a rotating polygon mirror combined with a DMD, on-axis interference imaging is selected, and the following steps are performed Step one, when the rectangular cyclic modulation pattern generation module selected for use is implemented based on a rotating polygon mirror combined with a DMD, on-axis interference imaging is selected, initial conditions and parameters for imaging are determined, and the initial conditions and parameters include: imaging resolution MxN of a wavefront to be measured, and number of steps of phase shifting Step two, determine the cyclic modulation pattern loaded on the digital micromirror device (3), the cyclic modulation pattern is a binary pattern directly loaded on the digital micromirror device (3) superimposed using a complex field modulation method, and the rectangular cyclic modulation pattern is a reference mode pattern, a cyclic modulation base pattern and a phase shift pattern superimposed together based on a complex field modulation method; Step three, build a single-pixel fast holographic imaging device based on a rotating polygon mirror combined with a DMD, the target spatial wave front is relayed to the action surface of the digital micromirror device (3) through multiple lenses, a rotating polygon mirror and a mirror, and the aperture r of the pinhole is determined, r≤1.22λƒ / d, wherein λ is the wavelength of the light beam incident to the focusing lens, ƒ is the focal length of the focusing lens, and d is the diameter of the light beam incident to the focusing lens; Step four, apply a pulse signal to the motor to start the rotation of the rotating polygon mirror, the target wave front is relayed to the action surface of the digital micromirror device through the rotating polygon mirror and the mirror, a modulation pattern is loaded on the action surface, the polygon mirror rotates to realize the scanning of the target light beam on the modulation pattern loaded on the digital micromirror device (3), the modulation of the incident light is realized, and the single-pixel detector collects the signal intensity value of the center point of the Fourier plane corresponding to each modulation pattern; Step five, reconstruct the target spatial wave front: obtain the complex coefficient spectrum of the target spatial wave front according to the phase shift technology, and restore the target spatial wave front by using a single-pixel reconstruction algorithm.

[0013] When the rectangular cyclic modulation pattern generation module selected for use is implemented based on a rotating polygon mirror combined with a DMD, off-axis interference imaging is selected, and the following steps are performed Step one, the rectangular cyclic modulation pattern generation module selected for use is a single-pixel fast holographic imaging device based on a rotating polygon mirror combined with a DMD, off-axis interference imaging is selected, and initial conditions and parameters for imaging are determined, the initial conditions and parameters including: imaging resolution M×N of the wave front to be measured, number of periods of the tilt phase grating, i.e. off-axis angle θ of the signal light relative to the reference light; Step two, determine the rectangular cyclic modulation pattern loaded on the digital micromirror device (3), the rectangular cyclic modulation pattern is a binary pattern directly loaded on the digital micromirror device (3) superimposed using a complex field modulation method, and the rectangular cyclic modulation pattern is a reference mode pattern, a cyclic modulation base pattern and a tilt phase grating superimposed together based on a complex field modulation method; Step three, build a single-pixel fast holographic imaging device based on a rotating polygon mirror combined with a DMD, the target spatial wave front is relayed to the action surface of the digital micromirror device (3) through multiple lenses, a rotating polygon mirror and a mirror, and the aperture r of the pinhole is determined, r≤1.22λƒ / d, wherein λ is the wavelength of the light beam incident to the focusing lens, ƒ is the focal length of the focusing lens, and d is the diameter of the light beam incident to the focusing lens; Step four, pulse signal is applied to the motor to make the rotating polygon mirror start to rotate, the target wave front passes through the rotating polygon mirror, the mirror relay to the digital micromirror device acting surface, the acting surface is loaded with a modulation pattern, the polygon mirror rotates to realize the scanning of the target beam to the modulation pattern loaded on the digital micromirror device (3), realize the modulation of incident light and interference, and the single-pixel detector collects the Fourier plane center point signal intensity value corresponding to each modulation pattern; Step five, reconstructing the target space wave front: according to the single-pixel detector collecting the Fourier plane center point interference signal intensity value corresponding to each modulation pattern, the off-axis hologram of the target is reconstructed by using the single-pixel reconstruction algorithm, and the spatial wave front of the target object is recovered according to the off-axis hologram by the Fourier fringe analysis method, so that the amplitude and phase of the target spatial wave front are obtained.

[0014] Compared with the prior art of using a spatial light modulator to load a traditional modulation pattern (such as Hadamard, Fourier, etc.) to realize single-pixel holography, the imaging resolution is not limited by the memory space of the traditional spatial light modulator, and the imaging resolution of single-pixel holographic imaging under full sampling rate is greatly improved, and meanwhile, the wave front imaging can be realized quickly in the mode of reducing the imaging resolution. The present application is suitable for biological imaging, three-dimensional measurement and microscopic imaging and the like. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a schematic diagram of a single-pixel holographic imaging device based on DMD; Figure 2 It is a schematic diagram of a ring-shaped mask plate transmission device; Figure 3 It is a schematic diagram of a ring-shaped mask plate reflection device; Figure 4 It is a schematic diagram of a single-pixel fast holographic imaging device based on a rotating polygon mirror combined with DMD; Figure 5 It is a cyclic S matrix pattern for partially modulating a signal light field, taking 101x103 pixels as an example, wherein the part framed by a black frame column is a modulation pattern displayed on the DMD; Figure 6 It is a different reference mode pattern, from left to right, it is a chessboard format reference mode pattern, a peripheral reference mode pattern and a random reference mode pattern; Figure 7 It is an amplitude and phase distribution diagram of a simulated target space wave front; Figure 8 It is a reconstruction result of a simulated target space wave front under different reference modes using four-step phase shifting in coaxial interference, from left to right, it is an amplitude and phase distribution diagram of a target space wave front reconstructed by a chessboard reference, and an amplitude and phase distribution diagram of a target space wave front reconstructed by a peripheral reference; Figure 9 The amplitude and phase distribution diagrams of the target spatial wavefronts obtained by the chessboard reference reconstruction and the peripheral reference reconstruction from left to right are shown in the figure; Wherein, 1, the first lens, 2, the second lens, 3, the digital micromirror device, 4, the focusing lens, 5, the pinhole, 6, the single-pixel detector, 7, the cube beam splitter, 8, the fourth lens, 9, the fifth lens, 10, the first mirror, 11, the rotating polygon mirror, 12, the second mirror, 13, the transmission annular mask, 14, the reflection annular mask, 15, the third lens. DETAILED DESCRIPTION

[0016] Embodiment one, a method for realizing single-pixel holographic imaging based on cyclic matrix modulation, the device used includes a rectangular cyclic modulation pattern generation module, a pinhole 5, a focusing lens 4 and a single-pixel detector 6, the pinhole 5 is placed at the back focal point position of the focusing lens 4 (the focal point position on the same side of the single-pixel detector), when the wavefront to be measured passes through the rectangular cyclic modulation pattern generation module, the rectangular cyclic modulation pattern generation module modulates the wavefront to be measured periodically, after the single-pixel detector 6 collects the signal intensity value of the center point of the Fourier plane after the modulation of the rectangular cyclic modulation pattern generation module, the target spatial wavefront is reconstructed. Figure 1 As shown in the figure, the single-pixel holographic imaging device based on DMD when the rectangular cyclic modulation pattern generation module is used includes a first lens 1, a second lens 2 and a digital micromirror device 3, the first lens 1 and the second lens 2 are coaxially placed with the digital micromirror device 3, the digital micromirror device 3 is at the horizontal focal length of the second lens 2, the first lens 1 and the second lens 2 constitute a 4-f system, the wavefront to be measured is irradiated to the digital micromirror device 3 after passing through the 4-f system and is modulated, the modulated light beam is detected by the single-pixel detector 6 after passing through the focusing lens 4 and the pinhole 5 to obtain the signal intensity value of the center point of the Fourier plane.

[0017] A method for realizing single-pixel holographic imaging based on cyclic matrix modulation, when the rectangular cyclic modulation pattern generation module based on DMD is selected, coaxial interference imaging is selected, as shown in the figure, the following steps are performed Figures 5-8 Step one, when the rectangular cyclic modulation pattern generation module based on DMD is selected, coaxial interference imaging is selected, the initial conditions and parameters of imaging are determined, the initial conditions and parameters include the imaging resolution MxN of the wavefront to be measured, the number of steps of phase shifting and the size of ROI on the digital micromirror device.

[0018] The imaging resolution of the spatial wavefront is determined to be 101x103, and the number of steps of phase shifting is four.

[0019] ​Step two, determine the rectangular cyclic modulation pattern loaded on the digital micro-mirror device 3, the rectangular cyclic modulation pattern is a binary pattern loaded on the digital micro-mirror device 3, the rectangular cyclic modulation pattern is a reference mode pattern, a cyclic modulation base pattern and a phase shift pattern combined and superimposed together based on a complex field modulation method, the cyclic modulation base pattern generation process is: generating a cyclic base matrix of MxN order by using a double prime number method, reshaping each row of the cyclic base matrix into a sub-matrix of MxN size, and then splicing each sub-matrix into a rectangular cyclic modulation pattern of Mx(MxN+N-1) in order, based on the complex field modulation method, converting the complex field of the rectangular cyclic modulation pattern into a binary pattern that can be directly loaded on the DMD.

[0020] A rectangular cyclic matrix with a spatial resolution size of 101x10505 is calculated, considering the signal-to-noise ratio and the selection of the reference mode, 4x4 micro-mirrors on the DMD represent one imaging pixel, i.e. the final rectangular cyclic matrix spatial resolution is 404x42020; a checkerboard reference pattern or a peripheral reference pattern with a spatial resolution of 404x42020 is generated; four four-step phase shift patterns with a spatial resolution of 404x42020 are generated. Superimpose the four-step phase shift patterns to the inverse checkerboard pattern or the inverse peripheral reference pattern, splice the composite modulation patterns of different phase shifts, and finally obtain a composite cyclic modulation pattern with a spatial resolution size of 404x168080.

[0021] The cyclic modulation base pattern is one of a cyclic S matrix base pattern, a Bernoulli matrix base pattern, a sparse random matrix base pattern, a Toeplitz matrix base pattern and a generalized cyclic matrix base pattern. Taking the cyclic S matrix as an example, the cyclic modulation base pattern generation process is: first, generate a cyclic s base matrix of 101x103 order by using a double prime number method, reshape each row of the base matrix into a sub-matrix of 101x103 size, and then splice each sub-matrix into a rectangular cyclic matrix base pattern of 101x10505 in order.

[0022] The reference mode pattern is one of a checkerboard reference mode pattern, an external reference mode pattern and a random reference mode pattern; the complex field modulation method is the Lee method or the superpixel method; the single-pixel reconstruction algorithm is the second-order correlation reconstruction algorithm or the compressed sensing reconstruction algorithm.

[0023] Superimpose the four-step phase shift patterns to the inverse checkerboard pattern or the inverse peripheral reference pattern, splice the composite modulation patterns of different phase shifts, and finally obtain a composite cyclic modulation pattern with a spatial resolution size of 404x168080.

[0024] Step three, build a single-pixel holographic imaging device based on DMD, and introduce the target spatial wave front into the digital micro-mirror device 3 surface through the 4-f system vertical illumination, determine the aperture r of the pinhole, r≤1.22λƒ / d, wherein λ is the wavelength of the incident light beam to the focusing lens, ƒ is the focal length of the focusing lens, and d is the diameter of the incident light beam to the focusing lens; Step four, load the rectangular cyclic modulation pattern on the digital micro-mirror device 3, set the ROI size on the digital micro-mirror device 3 according to the imaging resolution, set the scroll start line of the scroll program as the start line of the rectangular cyclic modulation pattern, set the scroll end line as the termination line of the rectangular cyclic modulation pattern, and set the scroll step as one imaging pixel each time. Each scrolling modulation pattern modulates the target in turn, and the single-pixel detector collects the Fourier plane center point signal intensity value corresponding to each scrolling modulation pattern.

[0025] The Lee method or superpixel is encoded into a binary pattern containing only 0 and 1 elements that can be loaded into the digital micro-mirror device, and then the ROI size on the DMD is set, the number of active ROI rows is 404; the scroll start line of the scroll program is set to 1, the scroll end line is set to 168080, and the scroll step is set to 4. Each scrolling modulation pattern modulates the target in turn, and the detector collects the Fourier plane center point signal intensity value corresponding to each modulation pattern Step five, reconstruct the target spatial wave front: obtain the complex coefficient spectrum of the target spatial wave front according to the phase shift technique, and recover the target spatial wave front using the single-pixel reconstruction algorithm.

[0026] When the rectangular cyclic modulation pattern generation module based on DMD is selected for use, off-axis interference imaging is selected, as shown in Figures 5-7 and Figure 9 The following steps are taken Step one, when the rectangular cyclic modulation pattern generation module based on DMD is selected for use, off-axis interference imaging is selected, and the initial conditions and parameters include: the imaging resolution of the wave front to be measured M×N, the off-axis angle θ of the signal light relative to the reference light, i.e. the number of periods of the tilted phase grating, and the ROI size on the digital micro-mirror device 3; determine the spatial wave front imaging resolution 101×103.

[0027] Step two, determine the rectangular cyclic modulation pattern loaded on the digital micro-mirror device 3, the rectangular cyclic modulation pattern is a combination of superimposed reference mode pattern, cyclic modulation base pattern and tilt phase grating, the generation process of the cyclic modulation base pattern is: generate a cyclic base matrix of MxN order by using the double prime number method, reshape each row of the cyclic base matrix into a sub-matrix of MxN size, and then splice each sub-matrix into a rectangular cyclic matrix base pattern of Mx(MxN+N-1) in order, the cyclic matrix base pattern is used for spatial sampling of the introduced wave front in the signal part, based on the complex field modulation method, the rectangular cyclic modulation pattern with complex value is converted into a binary pattern that can be directly loaded on the DMD.

[0028] A rectangular cyclic matrix with a spatial resolution of 101x10505 is calculated, considering the signal-to-noise ratio and the selection of the reference mode, 4x4 micro-mirrors on the DMD represent one imaging pixel, i.e. the final rectangular cyclic matrix spatial resolution is 404x42020; a checkerboard reference pattern or a peripheral reference pattern with a spatial resolution of 404x42020 is generated; a tilt phase grating with a spatial resolution of 404x42020 is generated.

[0029] Step three, build a single-pixel holographic imaging device based on DMD, the target spatial wave front is vertically irradiated to the surface of the digital micro-mirror device 3 through a 4-f system, the aperture r of the pinhole is determined, r≤1.22λƒ / d, wherein λ is the wavelength of the light beam incident to the focusing lens, ƒ is the focal length of the focusing lens, and d is the diameter of the light beam incident to the focusing lens; Step four, load the rectangular cyclic modulation pattern on the digital micro-mirror device (3), set the ROI size on the digital micro-mirror device 3 according to the imaging resolution, the number of activated rows is N, the rolling start row of the rolling program is set to the starting row of the rectangular cyclic modulation pattern, the rolling end row is set to the terminal row of the rectangular cyclic modulation pattern, and the rolling step is set to one imaging pixel at a time. Each rolling modulation pattern modulates the target in turn, while the single-pixel detector collects the Fourier plane center point signal intensity value corresponding to each rolling modulation pattern.

[0030] The inclined phase grating pattern is superimposed on the inverse chessboard pattern or the inverse peripheral reference pattern, different phase shift composite modulation patterns are spliced, and finally a composite cyclic modulation pattern with a spatial resolution of 404x42020 is obtained. The generated composite cyclic modulation pattern is encoded by Lee method or superpixel into a binary pattern containing only 0 and 1 elements which can be loaded into a digital micromirror device, then the ROI area on the DMD is set, the number of active ROI rows is 404; the scrolling start row of the scrolling program is set to 1, the scrolling end row is set to 42020, and the scrolling step is set to 4. Each scrolling modulation pattern modulates the target in turn, and the detector collects the Fourier plane center point signal intensity value corresponding to each modulation pattern.

[0031] Step five, reconstructing the target spatial wave front: first, according to the coefficient spectrum composed of the Fourier plane center point signal intensity value obtained by the single-pixel detector, the off-axis hologram of the target is reconstructed by using the single-pixel reconstruction algorithm, then according to the obtained off-axis hologram of the target, the spatial wave front of the target object is restored by the Fourier fringe analysis method, and the amplitude and phase of the target spatial wave front are obtained.

[0032] Embodiment two, a method for realizing single-pixel holographic imaging based on cyclic matrix modulation, the device used includes a rectangular cyclic modulation pattern generation module, a pinhole 5, a focusing lens 4 and a single-pixel detector 6, the pinhole 5 is placed at the back focal point position of the focusing lens 4 (the focal point position on the same side of the single-pixel detector), when the wave front to be measured passes through the rectangular cyclic modulation pattern generation module, the rectangular cyclic modulation pattern generation module periodically modulates the wave front to be measured, after the single-pixel detector 6 collects the Fourier plane center point signal intensity value modulated by the rectangular cyclic modulation pattern generation module, the target spatial wave front is reconstructed.

[0033] As shown in Figure 2 and 3 , the rectangular cyclic modulation pattern generation module is a single-pixel holographic imaging device realized based on a ring-shaped mask, which includes a ring-shaped mask transmission device and a ring-shaped mask reflection device.

[0034] The ring-shaped mask transmission device includes a first lens 1, a second lens 2 and a transmission ring-shaped mask 13, the first lens 1, the second lens 2, the transmission ring-shaped mask 13 and the focusing lens 4 are arranged in sequence, the first lens 1 and the second lens 2 constitute a 4-f system, the transmission ring-shaped mask 13 is at the horizontal focal length of the second lens 2, the wave front to be measured is irradiated to the transmission ring-shaped mask 13 through the 4-f system, the light beam transmitted by the transmission ring-shaped mask 13 is detected by the single-pixel detector 6 after passing through the focusing lens 4 and the pinhole 5 to obtain the Fourier plane center point signal intensity value.

[0035] The annular mask reflection device comprises a first lens 1, a second lens 2, a reflective annular mask 14, and a cube beam splitter 7, the first lens 1, the second lens 2, the cube beam splitter 7 and the reflective annular mask 14 are sequentially arranged, the line connecting the cube beam splitter 7 and the focusing lens 4 is perpendicular to the line connecting the first lens 1 and the second lens 2, after the wavefront to be measured is split by the cube beam splitter 7, one beam is irradiated to the reflective annular mask 14 and the other beam is irradiated to the focusing lens 4, the wavefront to be measured is irradiated to the cube beam splitter 7 through the 4-f system and is split into two light beams, one light beam is irradiated to the reflective annular mask 14 and is reflected back to the cube beam splitter 7, and the other light beam is irradiated to the focusing lens 4 and the pinhole 5 and then is detected by the single-pixel detector 6 to obtain the signal intensity value of the center point of the Fourier plane.

[0036] A method for implementing single-pixel holographic imaging based on a cyclic matrix modulation, when a rectangular cyclic modulation mode generation module is selected to generate a single-pixel holographic imaging device based on an annular mask.

[0037] In one embodiment, a cyclic S matrix is selected as a modulation base, a composite cyclic modulation mode after complex field modulation is etched on an annular mask, and a step of implementing annular mask-based cyclic matrix single-pixel fast holographic imaging based on a four-step phase shift scheme is implemented.

[0038] When coaxial interference imaging is selected, as shown in Figures 5-8 the following steps are performed Step one, when a rectangular cyclic modulation mode generation module is selected to generate a single-pixel holographic imaging device based on an annular mask, coaxial interference imaging is selected, initial conditions and parameters for imaging are determined, the initial conditions and parameters include: imaging resolution MxN of a wavefront to be measured, number of steps of phase shifting, size of a single pixel mapped on the annular mask, and rotating speed of an annular mask motor; imaging resolution 101x103 of a spatial wavefront, four steps of phase shifting, size of a single pixel mapped on the annular mask, and rotating speed of the annular mask motor are determined.

[0039] Step two, a rectangular cyclic modulation mode mapped on the annular mask is determined, the rectangular cyclic modulation mode is a binary mode mapped on the annular mask, the rectangular cyclic modulation mode is a reference mode pattern, a cyclic modulation base mode and a phase shifting mode combined and superimposed based on a complex field modulation method. A rectangular cyclic matrix with a spatial resolution size of 101x10505, a chessboard reference pattern or a peripheral reference pattern, and four phase shifting modes used for phase shifting operation are calculated and generated.

[0040] Step three, build a device based on the annular mask for single-pixel fast holographic imaging, the target space wave front is introduced into the annular mask by 4-f system vertical irradiation, the annular mask is a transmission annular mask 13 or a reflection annular mask 14, the aperture r of the pinhole is determined, r≤1.22λƒ / d, wherein, λ is the wavelength of the light beam incident to the focusing lens, ƒ is the focal length of the focusing lens, and d is the diameter of the light beam incident to the focusing lens; Step four, etching the modulation pattern of the annular mask, the motor is started to rotate by applying a pulse signal, and the incident light is modulated to interfere, the single-pixel detector collects the Fourier plane center point signal intensity value corresponding to each modulation pattern; the four-step phase shift pattern is superimposed on the inverse chessboard pattern or the inverse peripheral reference pattern, the composite modulation patterns with different phase shifts are spliced, and finally a composite cyclic modulation pattern is obtained, and then the complex field superimposed above is converted into a binary pattern which can be directly mapped on the annular mask using the complex field modulation method.

[0041] Step five, reconstructing the target space wave front: obtaining the complex coefficient spectrum of the target space wave front according to the phase shift technology, and restoring the target space wave front by using the single-pixel reconstruction algorithm.

[0042] When off-axis interference imaging is selected, as shown in FIGS. Figures 5-7 and Figure 9 the following steps are performed Step one, when the rectangular cyclic modulation pattern generation module based on the annular mask is selected, off-axis interference imaging is selected, and initial conditions and parameters are determined, the initial conditions and parameters include: the imaging resolution of the measured wave front M×N, the size of the single pixel mapped on the annular mask, the period number of the tilted phase grating, i.e. the off-axis angle θ of the signal light relative to the reference light, and the rotating speed of the annular mask motor; the initial parameters of the annular mask are determined: the spatial wave front imaging resolution is 101×103.

[0043] Step two, determine the rectangular cyclic modulation pattern mapped on the annular mask, the rectangular cyclic modulation pattern is a binary pattern mapped on the annular mask, the rectangular cyclic modulation pattern is a reference mode pattern, a cyclic modulation base pattern and a tilted phase grating which are combined and superimposed together based on the complex field modulation method. Calculate to generate a rectangular cyclic matrix with a spatial resolution size of 101×10505, a chessboard reference pattern or a peripheral reference pattern and a tilted phase grating.

[0044] Step three, build a device based on the annular mask for single-pixel fast holographic imaging, the target spatial wave front is introduced into the annular mask by 4-f system vertical irradiation, the annular mask is a transmission annular mask 13 or a reflection annular mask 14, the aperture r of the pinhole is determined, r≤1.22λƒ / d, wherein, λ is the wavelength of the incident light beam to the focusing lens, ƒ is the focal length of the focusing lens, and d is the diameter of the incident light beam to the focusing lens; Step four, etching the modulation pattern of the annular mask, the motor applies a pulse signal to start rotating, and the incident light is modulated and interfered, and the single-pixel detector collects the Fourier plane center point signal intensity value corresponding to each modulation pattern; the inclined phase grating pattern is superimposed on the inverse chessboard pattern or the inverse peripheral reference pattern, and finally a composite cyclic modulation pattern is obtained, and then the complex field modulation method is used to convert the superimposed complex field into a binary pattern which can be directly mapped on the annular mask.

[0045] Step five, reconstructing the target spatial wave front: first, according to the coefficient spectrum composed of the Fourier plane center point signal intensity value obtained by the single-pixel detector, the single-pixel reconstruction algorithm is used to reconstruct the off-axis hologram of the target, and then according to the obtained off-axis hologram of the target, the spatial wave front of the target object is recovered by the Fourier fringe analysis method, and the amplitude and phase of the target spatial wave front are obtained.

[0046] The complex field modulation method can adopt Lee method and super-pixel method. Taking Lee method as an example, which is one of the commonly used complex field modulation methods, the complex field modulation method in the embodiment is Lee method.

[0047] Embodiment three, a method for realizing single-pixel holographic imaging based on cyclic matrix modulation, the device used includes a rectangular cyclic modulation pattern generation module, a pinhole 5, a focusing lens 4 and a single-pixel detector 6, the pinhole 5 is placed at the back focal point position of the focusing lens 4 (the focal point position on the same side of the single-pixel detector), when the to-be-measured wave front passes through the rectangular cyclic modulation pattern generation module, the rectangular cyclic modulation pattern generation module modulates the to-be-measured wave front periodically, and after the single-pixel detector 6 collects the Fourier plane center point signal intensity value modulated by the rectangular cyclic modulation pattern generation module, the target spatial wave front is reconstructed.

[0048] As Figure 4As shown, the rectangular cyclic modulation pattern generation module is based on a single-pixel holographic imaging device realized by a rotating polygon mirror combined with a DMD, which comprises a first lens 1, a second lens 2, a third lens 15, a fourth lens 8, a fifth lens 9, a rotating polygon mirror 11, a first mirror 10, a second mirror 12, and a digital micromirror device 3. The digital micromirror device 3 is placed at the back focal point of the first lens 1. The second lens 2 and the third lens 15 form a 4-f system, and the connecting line of the second lens 2 and the third lens 15 is perpendicular to the axis of the first lens 1. The second mirror 12 is located on the reflected beam of the first mirror 10. The wavefront to be measured is irradiated to the rotating polygon mirror 11 through the first lens 1 to occur the first reflection, and the reflected light enters the second lens 2 and the third lens 15. The light beam emitted from the third lens 15 is reflected to the second mirror 12 by the first mirror 10. The reflected beam of the second mirror 12 enters the digital micromirror device 3 for modulation. The light beam modulated by the digital micromirror device 3 is irradiated to the rotating polygon mirror 11 to occur the second reflection, and the reflected light is reflected to the fifth lens 9 and the focusing lens 4 by the rotating polygon mirror 11. The light beam passing through the focusing lens 4 is detected by the single-pixel detector 6 after passing through the pinhole 5 to obtain the signal intensity value of the center point of the Fourier plane.

[0049] A method for realizing single-pixel holographic imaging based on cyclic matrix modulation, wherein a single-pixel holographic imaging device based on a rotating polygon mirror combined with a DMD is selected when a rectangular cyclic modulation pattern generation module is selected.

[0050] When coaxial interference imaging is selected, the following steps are performed Figures 5-8 As shown, the following steps are performed Step one, when a rectangular cyclic modulation pattern generation module based on a polygon mirror combined with a DMD is selected, coaxial interference imaging is selected, and initial conditions and parameters for imaging are determined, wherein the initial conditions and parameters include: imaging resolution M×N of the wavefront to be measured, and the number of steps for phase shifting; and the spatial wavefront imaging resolution is determined to be 101×103.

[0051] Step two, a rectangular cyclic modulation pattern loaded on the digital micromirror device 3 is determined, wherein the rectangular cyclic modulation pattern is a binary pattern directly loaded on the digital micromirror device 3 by using a complex field modulation method, and the rectangular cyclic modulation pattern is a reference mode pattern, a cyclic modulation base pattern, and a phase shifting pattern combined and superimposed together based on the complex field modulation method; Step three, a single-pixel fast holographic imaging device based on a rotating polygon mirror combined with a DMD is built, the target spatial wavefront is relayed to the acting surface of the digital micromirror device 3 through multiple lenses, a rotating polygon mirror, and a mirror, the aperture r of the pinhole is determined, and r≤1.22λƒ / d, wherein λ is the wavelength of the light beam incident to the focusing lens, ƒ is the focal length of the focusing lens, and d is the diameter of the light beam incident to the focusing lens. Step four, apply a pulse signal to the motor to start the rotating polygon mirror, the target wave front through the rotating polygon mirror, the mirror relay to the digital micro-mirror device acting surface, its acting surface is loaded with modulation mode, the polygon mirror rotates to realize the scanning of the target light beam to the modulation mode loaded on the digital micro-mirror device 3, realize the modulation and interference of incident light, and the single-pixel detector collects the Fourier plane center point signal intensity value corresponding to each modulation mode; Step five, reconstructing the target space wave front: obtaining the complex coefficient spectrum of the target space wave front according to the phase shift technique, and restoring the target space wave front by using the single-pixel reconstruction algorithm.

[0052] When selecting off-axis interference imaging, as shown in Figs. Figures 5-7 and Figure 9 , the following steps are taken Step one, select the rectangular cyclic modulation mode generation module based on the polygon mirror combined with the DMD, select the off-axis interference imaging, determine the initial conditions and parameters of imaging, the initial conditions and parameters include: the imaging resolution of the measured wave front MxN, the period number of the tilted phase grating, that is, the off-axis angle θ of the signal light relative to the reference light; determine the imaging resolution of the space wave front 101x103.

[0053] Step two, determine the rectangular cyclic modulation mode loaded on the digital micro-mirror device 3, the rectangular cyclic modulation mode is a binary mode directly loaded on the digital micro-mirror device 3 using the complex field modulation method, the rectangular cyclic modulation mode is a reference mode pattern, a cyclic modulation base mode and a tilted phase grating combined and superimposed based on the complex field modulation method; calculate and generate a rectangular cyclic matrix with a space resolution of 101x10505, a chessboard reference pattern or a peripheral reference pattern, and a tilted phase grating for off-axis operation.

[0054] Step three, build a single-pixel fast holographic imaging device based on the rotating polygon mirror combined with the DMD, the target space wave front passes through multiple lenses, a rotating polygon mirror and a mirror to the acting surface of the digital micro-mirror device 3, determine the aperture r of the pinhole, r≤1.22λƒ / d, wherein λ is the wavelength of the light beam incident to the focusing lens, ƒ is the focal length of the focusing lens, and d is the diameter of the light beam incident to the focusing lens; Step four, apply a pulse signal to the motor to start the rotating polygon mirror, the target wave front through the rotating polygon mirror, the mirror relay to the digital micro-mirror device acting surface, its acting surface is loaded with modulation mode, the polygon mirror rotates to realize the scanning of the target light beam to the modulation mode loaded on the digital micro-mirror device 3, realize the modulation and interference of incident light, and the single-pixel detector collects the Fourier plane center point signal intensity value corresponding to each modulation mode; Step five, reconstructing the target spatial wave front: according to the single-pixel detector collecting the intensity values of the interference signals corresponding to the center points of the Fourier planes of each modulation mode, the single-pixel reconstruction algorithm is used to reconstruct the off-axis hologram of the target, and the spatial wave front of the target object is recovered according to the off-axis hologram through the Fourier fringe analysis method, so that the amplitude and phase of the target spatial wave front are obtained.

[0055] One embodiment takes the imaging of a to-be-measured spatial wave front with an amplitude limited to a circular ring and a phase distribution in the shape of a "pepper" as an example, and embodiment four, as shown in the figure, carries out the wave front imaging of the above combined to-be-measured wave front according to the steps of the scheme of the present application, and the amplitude and phase distribution of the to-be-measured wave front are obtained by the second-order correlation reconstruction of the to-be-measured wave front, as shown in the figures. Figure 7 Figure 8 Figure 9

[0056] The present application uses the movable cyclic modulation mode generated by the cyclic matrix to replace the traditional modulation mode, and the switching of the modulation mode can be realized by moving only one column of the whole modulation mode each time. The memory of the modulation device occupied by the modulation mode is greatly saved. The frame rate of the imaging system can be free from the limitation of the refresh rate of the traditional spatial light modulator, and the speed of the single-pixel holographic imaging is improved. The present application is implemented by the following three schemes: in the first scheme, the cyclic modulation mode is loaded onto the DMD, and the development of the ROI function effectively improves the refresh rate of the DMD, and under this premise, the combination of the cyclic modulation mode and the rolling function of the DMD can realize fast imaging; in the second scheme, the cyclic modulation mode is mapped to a ring-shaped mask plate, and different spatial modulation modes are periodically modulated to the target by periodically rotating the mask plate, so that the single-pixel wave front detection is finally realized, and fast imaging can also be realized by changing the rotating speed of the motor to drive the mask plate; in the third scheme, the cyclic rectangular modulation mode is loaded onto the DMD, and the high-speed horizontal scanning of the rotating polygon mirror is combined to realize the high-speed periodic modulation of different spatial modulation modes to the target, and this way can also realize fast imaging by changing the rotating speed of the rotating mirror.

[0057] The above only describes the preferred embodiments of the present application, and the protection scope of the present application is not limited to the above-described embodiments. Any technical solution falling within the concept of the present application shall fall within the protection scope of the present application. It should be noted that, for ordinary technical personnel in the technical field, some improvements and refinements without departing from the principle of the present application shall also be considered as the protection scope of the present application.​​​

Claims

1. A method for achieving single-pixel holographic imaging based on cyclic matrix modulation, characterized by: Follow the steps below Step 1: Select a rectangular cyclic modulation pattern generation module to be used, select on-axis interferometric imaging or off-axis interferometric imaging, and determine initial imaging conditions and parameters, which include: the measured wavefront imaging resolution M×N and the corresponding parameters of the rectangular cyclic modulation pattern generation module; Step 2: Determine the rectangular cyclic modulation pattern loaded on the rectangular cyclic modulation pattern generation module. If it is on-axis interferometric imaging, the rectangular cyclic modulation pattern includes a cyclic modulation base pattern, a reference mode pattern, and a phase shift pattern. If it is off-axis interferometric imaging, the rectangular cyclic modulation pattern includes a cyclic modulation base pattern, a reference mode pattern, and a tilted phase grating. The reference mode pattern is used to partition the incident wavefront, dividing the incident wavefront into a reference part and a signal part, and its spatial resolution is consistent with the cyclic modulation pattern. The cyclic modulation base pattern is used to spatially sample the introduced wavefront in the signal part. The phase shift pattern is used to introduce a fixed phase difference between the reference beam and the signal beam. The tilted phase grating is used to introduce an off-axis angle between the reference beam and the signal beam to generate a linear phase difference. Step 3: Based on the selected rectangular cyclic modulation pattern generation module, build a device for single-pixel holographic imaging based on cyclic matrix modulation, and determine the aperture r of the pinhole, r≤1.22λƒ / d, where λ is the wavelength of the light beam incident on the focusing lens, ƒ is the focal length of the focusing lens, and d is the diameter of the light beam incident on the focusing lens; Step 4: Load the modulation pattern on the rectangular cyclic modulation pattern generation module, and at the same time, the single-pixel detector collects the signal intensity value of the center point of the Fourier plane corresponding to each modulation pattern; Step 5. Reconstruct the target spatial wavefront: For on-axis interferometric imaging, the complex coefficient spectrum of the target spatial wavefront is obtained based on the phase shifting technology, and the target spatial wavefront is restored using the single-pixel reconstruction algorithm; for off-axis interferometric imaging, the off-axis hologram of the target is first reconstructed using the single-pixel reconstruction algorithm, and then based on the obtained off-axis hologram of the target, the spatial wavefront of the target object is restored through the Fourier fringe analysis method, and the amplitude and phase of the target spatial wavefront are obtained at the same time.

2. The method for realizing single-pixel holographic imaging based on cyclic matrix modulation according to claim 1, characterized in that: The cyclic modulation base pattern is one of a cyclic S matrix pattern, a Bernoulli matrix pattern, a sparse random matrix pattern, a Toeplitz matrix pattern and a generalized cyclic matrix pattern; the reference mode pattern is one of a checkerboard reference mode pattern, an external reference mode pattern and a random reference mode pattern; the complex field modulation method is a Lee method or a superpixel method; the single pixel reconstruction algorithm is a second-order correlation reconstruction algorithm or a compressed sensing reconstruction algorithm.

3. The method for realizing single-pixel holographic imaging based on cyclic matrix modulation according to claim 2, characterized in that: The device used in the method includes a rectangular cyclic modulation pattern generation module, a pinhole (5), a focusing lens (4) and a single-pixel detector (6), wherein the pinhole (5) is placed at the rear focus position of the focusing lens (4), and when the wavefront to be measured passes through the rectangular cyclic modulation pattern generation module, the rectangular cyclic modulation pattern generation module periodically modulates the wavefront to be measured, and the single-pixel detector (6) collects the signal intensity value of the center point of the Fourier plane modulated by the rectangular cyclic modulation pattern generation module, and reconstructs the target space wavefront; the rectangular cyclic modulation pattern generation module is a single-pixel holographic imaging device based on DMD, a single-pixel fast holographic imaging device based on an annular mask and a rotating multi-faceted holographic imaging device based on a rotating multi-faceted holographic imaging device. A device for single-pixel fast holographic imaging based on a micromirror and a DMD; the single-pixel holographic imaging device based on the DMD comprises: a first lens (1), a second lens (2) and a digital micromirror device (3); the first lens (1) and the second lens (2) are coaxially arranged with the digital micromirror device (3); the digital micromirror device (3) is at the horizontal focal length of the second lens (2); the first lens (1) and the second lens (2) form a 4-f system; the wavefront to be measured passes through the 4-f system and is irradiated onto the digital micromirror device (3) to be modulated; the modulated light beam passes through a focusing lens (4) and a pinhole (5) and is detected by a single-pixel detector (6) to obtain a signal intensity value at the center point of the Fourier plane;The device for single-pixel fast holographic imaging based on an annular mask comprises an annular mask transmission device and an annular mask reflection device, wherein the annular mask transmission device comprises: a first lens (1), a second lens (2) and a transmission annular mask (13), wherein the first lens (1), the second lens (2), the transmission annular mask (13) and a focusing lens (4) are arranged in sequence, wherein the first lens (1) and the second lens (2) form a 4-f system, wherein the transmission annular mask (13) is located at the horizontal focal length of the second lens (2), and the wavefront to be measured is irradiated onto the transmission annular mask (13) through the 4-f system, and the light beam transmitted by the transmission annular mask (13) passes through the focusing lens (4) and the pinhole (5) and is detected by the single-pixel detector (6) to obtain a signal intensity value at the center point of the Fourier plane. A mirror (1), a second lens (2), a reflective annular mask (14), and a cube beam splitter (7), wherein the first lens (1), the second lens (2), the cube beam splitter (7), and the reflective annular mask (14) are arranged in sequence, and a line connecting the cube beam splitter (7) and the focusing lens (4) is perpendicular to a line connecting the first lens (1) and the second lens (2). After the wavefront to be measured is split by the cube beam splitter (7), one beam is irradiated onto the reflective annular mask (14) and the other beam is irradiated onto the focusing lens (4). The wavefront to be measured is irradiated onto the cube beam splitter (7) through a 4-f system and is split into two beams. One beam is irradiated onto the reflective annular mask (14) and is reflected back to the cube beam splitter (7) along the original path. The beam is then reflected back to the focusing lens (4) and the pinhole (5), and then the signal intensity value of the center point of the Fourier plane is detected by a single pixel detector (6).The single-pixel fast holographic imaging device based on a rotating polygonal mirror combined with a DMD comprises: a first lens (1), a second lens (2), a third lens (15), a fourth lens (8), a fifth lens (9), a rotating polygonal mirror (11), a first reflector (10), a second reflector (12), and a digital micromirror device (3), wherein the digital micromirror device (3) is placed at the rear focus position of the first lens (1), the second lens (2) and the third lens (15) form a 4-f system, the line connecting the second lens (2) and the third lens (15) is perpendicular to the axis of the first lens (1), the second reflector (12) is located on the reflected light beam of the first reflector (10), and the wavefront to be measured passes through the first lens (1) The light beam is irradiated onto the rotating polygonal mirror (11) and undergoes a first reflection. The light beam is reflected by the rotating polygonal mirror (11) and enters the second lens (2) and the third lens (15). The light beam emitted from the third lens (15) is reflected by the first reflector (10) to the second reflector (12). The reflected light beam of the second reflector (12) enters the digital micromirror device (3) for modulation. The light beam modulated by the digital micromirror device (3) is irradiated onto the rotating polygonal mirror (11) and undergoes a second reflection. The light beam is reflected by the rotating polygonal mirror (11) to the fifth lens (9) and the focusing lens (4). The light beam passing through the focusing lens (4) passes through the pinhole (5) and is detected by the single pixel detector (6) at the center point of the Fourier plane.

4. The method for realizing single-pixel holographic imaging based on cyclic matrix modulation according to claim 3, characterized in that: When the rectangular cyclic modulation pattern generation module is selected based on DMD implementation, select coaxial interferometric imaging and follow the steps below. Step 1: When the rectangular cyclic modulation pattern generation module is selected and implemented based on DMD, coaxial interferometric imaging is selected and initial imaging conditions and parameters are determined. The initial conditions and parameters include: the imaging resolution M×N of the wavefront to be measured and the number of multi-step phase shifting steps and the size of the region of interest on the digital micromirror device (3); Step 2: Determine the rectangular cyclic modulation pattern loaded on the digital micromirror device (3), wherein the rectangular cyclic modulation pattern is a binary pattern loaded on the digital micromirror device (3), wherein the rectangular cyclic modulation pattern is a reference pattern, a cyclic modulation base pattern and a phase shift pattern superimposed together based on a complex field modulation method, wherein the cyclic modulation base pattern generation process is as follows: generate an M×N order cyclic base matrix using a double prime number method, reshape each row of the cyclic base matrix into an M×N size submatrix, and then sequentially splice each submatrix into a rectangular cyclic modulation pattern with a dimension of M×(M×N+N-1), and convert the complex valued cyclic modulation pattern into a binary pattern that can be directly loaded on the DMD based on the complex field modulation method; Step 3: Build a single-pixel holographic imaging device based on DMD, introduce the target spatial wavefront into the surface of the digital micromirror device (3) through a 4-f system, and determine the aperture r of the pinhole, r≤1.22λƒ / d, where λ is the wavelength of the light beam incident on the focusing lens, ƒ is the focal length of the focusing lens, and d is the diameter of the light beam incident on the focusing lens; Step 4: Load the rectangular cyclic modulation pattern on the digital micromirror device (3), set the ROI size on the digital micromirror device (3) according to the imaging resolution, set the number of ROI activation rows to N, set the scrolling start row of the scrolling program to the start row of the rectangular cyclic modulation pattern, set the scrolling end row to the end row of the rectangular cyclic modulation pattern, and set the scrolling step length to one imaging pixel each time. Each scrolling modulation pattern of the digital micromirror device modulates the target in turn, and at the same time, the single-pixel detector collects the signal intensity value of the center point of the Fourier plane corresponding to each scrolling modulation pattern; Step 5: Reconstruct the target spatial wavefront: Obtain the complex coefficient spectrum of the target spatial wavefront based on the phase shifting technique, and use the single-pixel reconstruction algorithm to restore the target spatial wavefront.

5. The method for realizing single-pixel holographic imaging based on cyclic matrix modulation according to claim 3, characterized in that: When the rectangular cyclic modulation generation module is selected based on DMD implementation, select off-axis interferometric imaging and follow the steps below. Step 1: When the rectangular cyclic modulation pattern generation module is implemented based on DMD, off-axis interferometric imaging is selected. The initial conditions and parameters include: the imaging resolution of the wavefront to be measured M×N and the off-axis angle θ of the signal light relative to the reference light, that is, the number of periods of the tilted phase grating and the size of the ROI on the digital micromirror device (3); Step 2: Determine the rectangular cyclic modulation pattern loaded on the digital micromirror device (3), wherein the rectangular cyclic modulation pattern is a combination of a reference pattern, a cyclic modulation base pattern and a tilted phase grating, and the cyclic modulation base pattern generation process is as follows: generate an M×N order cyclic base matrix using a double prime number method, reshape each row of the cyclic base matrix into an M×N size sub-matrix, and then sequentially splice each sub-matrix into a rectangular cyclic modulation pattern with a dimension of M×(M×N+N-1), and convert the complex-valued rectangular cyclic modulation pattern into a binary pattern that can be directly loaded on the DMD; Step 3: Build a single-pixel holographic imaging device based on DMD, introduce the target spatial wavefront into the surface of the digital micromirror device (3) through a 4-f system, and determine the aperture r of the pinhole, r≤1.22λƒ / d, where λ is the wavelength of the light beam incident on the focusing lens, ƒ is the focal length of the focusing lens, and d is the diameter of the light beam incident on the focusing lens; Step 4: Load the rectangular cyclic modulation pattern on the digital micromirror device (3), set the ROI size on the digital micromirror device (3) according to the imaging resolution, set the number of activated rows to N, set the scrolling start row of the scrolling program to the start row of the rectangular cyclic modulation pattern, set the scrolling end row to the end row of the rectangular cyclic modulation pattern, set the scrolling step to one imaging pixel each time, and modulate the target in turn for each scrolling modulation pattern. At the same time, the single-pixel detector collects the signal intensity value of the center point of the Fourier plane corresponding to each scrolling modulation pattern. Step 5. Reconstruct the target spatial wavefront: First, based on the coefficient spectrum composed of the signal intensity values ​​of the center point of the Fourier plane obtained by the single-pixel detector, use the single-pixel reconstruction algorithm to reconstruct the off-axis hologram of the target. Then, based on the off-axis hologram of the target, the spatial wavefront of the target object is restored through the Fourier fringe analysis method to obtain the amplitude and phase of the target spatial wavefront.

6. The method for realizing single-pixel holographic imaging based on cyclic matrix modulation according to claim 3, characterized in that: When the rectangular cyclic modulation pattern generation module is selected based on the annular mask, select coaxial interferometric imaging and follow the steps below. Step 1: When the rectangular cyclic modulation pattern generation module is implemented based on an annular mask, coaxial interferometric imaging is selected and initial imaging conditions and parameters are determined. The initial conditions and parameters include: the measured wavefront imaging resolution M×N, the number of multi-step phase shifting steps, the size of a single pixel mapped on the annular mask, and the speed of the annular mask motor; Step 2: Determine a rectangular cyclic modulation pattern mapped on an annular mask, wherein the rectangular cyclic modulation pattern is a binary pattern mapped on the annular mask, and the rectangular cyclic modulation pattern is a reference mode pattern, a cyclic modulation base pattern, and a phase shift pattern superimposed together based on a complex field modulation method; Step 3: Build a single-pixel fast holographic imaging device based on an annular mask, introduce the target spatial wavefront into the active surface of the annular mask through vertical illumination of the 4-f system, the annular mask is a transmission annular mask (13) or a reflection annular mask (14), and determine the aperture r of the pinhole, r≤1.22λƒ / d, where λ is the wavelength of the light beam incident on the focusing lens, ƒ is the focal length of the focusing lens, and d is the diameter of the light beam incident on the focusing lens; Step 4: The annular mask etched with the modulation pattern is rotated by applying a pulse signal to the motor. The rotation of the annular mask shifts and switches the modulation pattern, modulating the incident light and causing interference. At the same time, a single-pixel detector collects the signal intensity value at the center point of the Fourier plane corresponding to each modulation pattern. Step 5: Reconstruct the target spatial wavefront: Obtain the complex coefficient spectrum of the target spatial wavefront based on the phase shifting technique, and use the single-pixel reconstruction algorithm to restore the target spatial wavefront.

7. The method for realizing single-pixel holographic imaging based on cyclic matrix modulation according to claim 3, characterized in that: When the rectangular cyclic modulation pattern generation module is selected based on the annular mask, select off-axis interferometric imaging and follow the steps below. Step 1: When the rectangular cyclic modulation pattern generation module is implemented based on an annular mask, off-axis interferometric imaging is selected and initial imaging conditions and parameters are determined. The initial conditions and parameters include: the imaging resolution of the wavefront to be measured (M×N), the size of a single pixel mapped on the annular mask, the number of periods of the tilted phase grating (i.e., the off-axis angle θ of the signal light relative to the reference light), and the rotational speed of the annular mask motor; Step 2: Determine a rectangular cyclic modulation pattern mapped on an annular mask, wherein the rectangular cyclic modulation pattern is a binary pattern mapped on the annular mask, and the rectangular cyclic modulation pattern is a reference mode pattern, a cyclic modulation base pattern, and a tilted phase grating combined and superimposed based on a complex field modulation method; Step 3: Build a single-pixel fast holographic imaging device based on an annular mask, introduce the target spatial wavefront into the active surface of the annular mask through vertical illumination of the 4-f system, the annular mask is a transmission annular mask (13) or a reflection annular mask (14), and determine the aperture r of the pinhole, r≤1.22λƒ / d, where λ is the wavelength of the light beam incident on the focusing lens, ƒ is the focal length of the focusing lens, and d is the diameter of the light beam incident on the focusing lens; Step 4: The annular mask etched with the modulation pattern is rotated by applying a pulse signal to the motor. The rotation of the annular mask shifts and switches the modulation pattern, modulating the incident light and causing interference. At the same time, a single-pixel detector collects the signal intensity value at the center point of the Fourier plane corresponding to each modulation pattern. Step 5. Reconstruct the target spatial wavefront: First, based on the coefficient spectrum composed of the signal intensity values ​​of the center point of the Fourier plane obtained by the single-pixel detector, use the single-pixel reconstruction algorithm to reconstruct the off-axis hologram of the target. Then, based on the obtained off-axis hologram of the target, the spatial wavefront of the target object is restored through the Fourier fringe analysis method, and the amplitude and phase of the target spatial wavefront are obtained at the same time.

8. The method for realizing single-pixel holographic imaging based on cyclic matrix modulation according to claim 3, characterized in that: When the rectangular cyclic modulation pattern generation module is selected based on the rotating polygon mirror combined with DMD, select coaxial interferometric imaging and follow the steps below. Step 1: When the rectangular cyclic modulation pattern generation module is implemented based on a rotating polygonal mirror combined with a DMD, coaxial interferometric imaging is selected and initial imaging conditions and parameters are determined. The initial conditions and parameters include: the imaging resolution of the wavefront to be measured (M×N) and the number of multi-step phase shifting steps; Step 2: determining a rectangular cyclic modulation pattern loaded on the digital micromirror device (3), wherein the rectangular cyclic modulation pattern is a binary pattern directly loaded on the digital micromirror device (3) superimposed using a complex field modulation method, and the rectangular cyclic modulation pattern is a reference mode pattern, a cyclic modulation base pattern, and a phase shift pattern superimposed together based on the complex field modulation method; Step 3: Build a single-pixel fast holographic imaging device based on a rotating polygonal mirror combined with a DMD. The target spatial wavefront is relayed to the working surface of the digital micromirror device (3) through multiple lenses, a rotating polygonal mirror, and a reflector. The aperture r of the pinhole is determined, r≤1.22λƒ / d, where λ is the wavelength of the light beam incident on the focusing lens, ƒ is the focal length of the focusing lens, and d is the diameter of the light beam incident on the focusing lens. Step 4: Apply a pulse signal to the motor to start the rotation of the rotating polygonal mirror. The target wavefront is relayed to the active surface of the digital micromirror device (3) through the rotating polygonal mirror and the reflector. The modulation pattern is loaded on the active surface. The polygonal mirror rotates to realize the scanning of the modulation pattern loaded on the digital micromirror device by the target light beam, thereby realizing the modulation of the incident light and causing interference. At the same time, the single-pixel detector collects the signal intensity value of the center point of the Fourier plane corresponding to each modulation pattern. Step 5: Reconstruct the target spatial wavefront: Obtain the complex coefficient spectrum of the target spatial wavefront based on the phase shifting technique, and use the single-pixel reconstruction algorithm to restore the target spatial wavefront.

9. The method for realizing single-pixel holographic imaging based on cyclic matrix modulation according to claim 3, characterized in that: When the rectangular cyclic modulation pattern generation module is selected based on the rotating polygon mirror combined with DMD, off-axis interferometric imaging is selected and the following steps are performed. Step 1: When the rectangular cyclic modulation pattern generation module is implemented based on a rotating polygon mirror combined with a DMD, off-axis interferometric imaging is selected and initial imaging conditions and parameters are determined. The initial conditions and parameters include: the imaging resolution of the wavefront to be measured M×N, the number of periods of the tilted phase grating, that is, the off-axis angle θ of the signal light relative to the reference light; Step 2: determining a rectangular cyclic modulation pattern loaded on the digital micromirror device (3), wherein the rectangular cyclic modulation pattern is a binary pattern directly loaded on the digital micromirror device (3) superimposed using a complex field modulation method, and the rectangular cyclic modulation pattern is a reference pattern, a cyclic modulation base pattern, and a tilted phase grating superimposed together based on the complex field modulation method; Step 3: Build a single-pixel fast holographic imaging device based on a rotating polygonal mirror combined with a DMD. The target spatial wavefront is relayed to the working surface of the digital micromirror device (3) through multiple lenses, a rotating polygonal mirror, and a reflector. The aperture r of the pinhole is determined, r≤1.22λƒ / d, where λ is the wavelength of the light beam incident on the focusing lens, ƒ is the focal length of the focusing lens, and d is the diameter of the light beam incident on the focusing lens. Step 4: Apply a pulse signal to the motor to start the rotation of the rotating polygonal mirror. The target wavefront is relayed to the active surface of the digital micromirror device through the rotating polygonal mirror and the reflector. The modulation pattern is loaded on the active surface. The polygonal mirror rotates to realize the target light beam scanning the modulation pattern loaded on the digital micromirror device, thereby modulating the incident light and causing interference. At the same time, the single-pixel detector collects the signal intensity value of the center point of the Fourier plane corresponding to each modulation pattern. Step 5. Reconstruct the target spatial wavefront: Based on the single-pixel detector, the interference signal intensity value of the center point of the Fourier plane corresponding to each modulation mode is collected, and the off-axis hologram of the target is reconstructed using the single-pixel reconstruction algorithm. Based on the off-axis hologram, the spatial wavefront of the target object is restored through the Fourier fringe analysis method to obtain the amplitude and phase of the target spatial wavefront.

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