A wavefront shaping system and method based on spatial division multiplexing

Abstract

The application discloses a wavefront shaping system and method based on spatial division multiplexing. After the light beam emitted by a laser light source is expanded, modulated by a spatial light modulator, and passed through a rotating mask and a series of optical systems, the light beam is collected by a photoelectric detector. The laser light source enters the spatial light modulator. In a refresh cycle of the spatial light modulator, the rotating mask is rotated. For the sub-regions turned into the light path, the wavefront of the light beam is modulated by the modulation regions corresponding to the sub-regions. Finally, the wavefront is collected by the photoelectric detector. Then, a control unit processes four groups of signals obtained by using a wavefront shaping algorithm to obtain four groups of preliminary correction wavefront parameters. The rotating mask is removed, and the wavefronts of the four groups of correction wavefronts are matched to obtain a final correction wavefront signal. The application can realize accurate focusing of light after the light transmits through a scattering medium, and can realize higher light intensity gain under the same correction time.

Description

Technical Field

[0001] This invention belongs to the field of wavefront shaping technology, specifically relating to a wavefront shaping system and method based on spatial segmentation and multiplexing. Background Technology

[0002] Wavefront shaping technology is widely used in optical detection in complex scenarios, such as astronomical observation, laser processing, and biomedical imaging and therapy. This technology modulates the light field using various light modulation devices, such as spatial light modulators, deformable mirrors, and digital micromirror devices, to correct scattering and aberrations, and precisely guide the incident light to the target point.

[0003] Traditional wavefront shaping methods based on feedback signal modulation mostly involve applying different modulation signals to different zones of an optical modulator and collecting feedback signals as the basis for further adjustment. More and denser zones result in a greater final calibrated light intensity, but the more zones required on the optical modulator, the longer the total time for the photodetector to collect signals, thus affecting real-time calibration applications.

[0004] When feedback-based wavefront shaping algorithms probe deep, strongly scattering samples, a larger number of partitions is required due to the need for a higher signal-to-noise ratio in the adversarial scattering medium, thus necessitating a longer correction time. Traditional feedback-based wavefront shaping methods require a long time to correct scattering, making them difficult to apply in scattering media with short decoherence times. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a wavefront shaping system and method based on spatial segmentation and multiplexing. This invention modulates light using a rotating mask, enabling simultaneous correction of scattering in four sub-regions. Through wavefront matching, a total corrected wavefront is obtained. Therefore, this invention significantly improves the correction effect of wavefront shaping methods.

[0006] The technical solution adopted in this invention is as follows:

[0007] I. A Wavefront Shaping System Based on Spatial Segmentation and Multiplexing

[0008] The wavefront shaping system includes a laser source, a first beam expander, a spatial light modulator, a rotating mask, a second beam expander, a first objective lens, a scattering medium, a second objective lens, a tube lens, and a photodetector, arranged sequentially along the optical path. The beam emitted by the laser source passes through the first beam expander, then enters the spatial light modulator for modulation. After modulation, it passes sequentially through the rotating mask, the second beam expander, and the first objective lens, then through the scattering medium, and then sequentially through the second objective lens and the tube lens before being collected by the photodetector. The spatial light modulator, the rotating mask, and the photodetector are connected to a control unit, which is used to drive and control the rotation of the rotating mask, control the modulation signal refresh of the spatial light modulator, and receive and process the signals collected by the photodetector.

[0009] The scattering medium can be specifically a slice of mouse brain. The first beam expander fills the light path of the spatial light modulator, improving its efficiency. The second beam expander fills the entrance aperture of the objective lens, increasing the numerical aperture of the system. The tube lens converges the light to form the final real image.

[0010] The spatial light modulator is located on the front focal plane of the first objective lens, and the spatial light modulator and the first objective lens are arranged coaxially.

[0011] The size of the rotating mask is consistent with the photosensitive size of the spatial light modulator. The rotating mask is divided into four sub-regions, of which only one sub-region is transparent, and the transmittance of the remaining sub-regions is ≤0.01%, approximately 0. The modulation surface of the spatial light modulator is divided into four modulation regions, and the four modulation regions correspond one-to-one with the four sub-regions of the rotating mask in space.

[0012] The rotating mask is divided into 2×2 sub-regions. Based on the geometric center (i.e., the center of the circle) of the rotating mask, the rotating mask is divided into four equal sub-regions by two mutually perpendicular straight lines.

[0013] The scattering medium is positioned in front of the focal plane of the first objective lens; the photodetector is positioned on the focal plane of the tube lens, and the photodetector and the tube lens are arranged coaxially.

[0014] The first objective lens is conjugate to the second objective lens, and the first objective lens and the second objective lens are arranged coaxially, with their focal points coinciding; the second objective lens is conjugate to the tube lens, and the second objective lens and the tube lens are arranged coaxially, with their focal points coinciding.

[0015] The spatial light modulator is one of the following: a full-phase spatial light modulator, a ferroelectric liquid crystal binarized phase-type spatial light modulator, or a digital micromirror; the photodetector is one of the following: a photomultiplier tube, an avalanche photodiode, or a silicon-based photodetector.

[0016] II. Wavefront Shaping Method Based on Spatial Segmentation and Multiplexing System

[0017] Wavefront shaping methods include the following steps:

[0018] S1. The laser light source emits a beam, which is expanded by the first beam expander and then enters the spatial light modulator.

[0019] S2. Configure the rotation period of the rotating mask through the control unit to coordinate it with the refresh period of the spatial light modulator;

[0020] Specifically, the rotation period of the rotating mask is configured so that the time for the rotating mask to complete a 360° rotation does not exceed the refresh period of the spatial light modulator. Within one complete rotation period of the rotating mask, each sub-region sequentially enters the optical path.

[0021] S3. Within one refresh cycle of the spatial light modulator, the control unit drives the rotating mask to rotate, so that the four sub-regions sequentially enter the optical path. For each sub-region that enters the optical path, the beam wavefront (phase or amplitude) is modulated by the modulation region corresponding to that sub-region. The modulated beam is then transmitted and collected by the photodetector, and converted into a set of electrical signals. Thus, four sets of electrical signals are obtained sequentially and transmitted to the control unit.

[0022] Specifically, within one refresh cycle of the spatial light modulator, the control unit drives the rotating mask to rotate, causing the four sub-regions to sequentially enter the optical path. For each sub-region entering the optical path, the beam wavefront (phase or amplitude) is modulated by the modulation region corresponding to that sub-region in the spatial light modulator. The modulated beam sequentially passes through the second beam expander, the first objective lens, the scattering medium, the second objective lens, and the tube lens before being collected by the photodetector and converted into a corresponding set of electrical signals. Thus, four sets of electrical signals are sequentially obtained and transmitted to the control unit.

[0023] S4. The post-control unit sequentially processes the four sets of electrical signals using a wavefront shaping algorithm to obtain four sets of preliminary corrected wavefront parameters. The preliminary corrected wavefront parameters are specifically phase or amplitude parameters. In step S4, the wavefront shaping algorithm is one of the following: transfer matrix algorithm, genetic algorithm, or coherent optical adaptive technology.

[0024] S5. Remove the rotating mask so that the beams from all four sub-regions are collected by the photodetector. Wavefront matching is performed sequentially on the four preliminary correction wavefronts to obtain a complete correction wavefront (phase or amplitude). This final complete wavefront is used as the modulation signal in the spatial light modulator. The four final correction wavefronts (phase or amplitude) are then used as new modulation signals for the four modulation regions in the spatial light modulator. In step S5, wavefront matching involves keeping the amplitude wavefront distribution of one sub-region unchanged, sequentially inverting the amplitude wavefront distribution parameters of the other three sub-regions, and iteratively optimizing based on the photodetector signal to maximize the light intensity signal of that sub-region.

[0025] This invention enables precise focusing of light after it passes through a scattering medium, and achieves higher light intensity gain with the same correction time.

[0026] The beneficial effects of this invention are:

[0027] Traditional wavefront shaping methods are limited by the number of partitions in the spatial light modulator, resulting in long correction times and low signal-to-noise ratios for strongly scattering media. This invention utilizes a rotating mask to acquire feedback modulation signals from four sub-regions within the same spatial light modulator cycle, achieving spatial multiplexing of the feedback signals and significantly improving the signal correction effect. Attached Figure Description

[0028] Figure 1 This is a flowchart of the present invention.

[0029] Figure 2 This is a schematic diagram of the wavefront shaping system for spatial segmentation and multiplexing according to the present invention.

[0030] Figure 3 This is a schematic diagram of the rotating mask of the present invention.

[0031] Figure 4 These are the speckle pattern at the focal plane of the first objective lens in this embodiment of the invention and the speckle patterns of the four sub-regions modulated by the rotating mask. Here, a is the speckle pattern obtained after removing the rotating mask, and b, c, d, and e represent the speckle patterns obtained after the four sub-regions (upper, lower, left, and right) are sequentially passed through the mask after being filtered by the rotating mask.

[0032] Figure 5 These are the light intensity distribution map and the corresponding corrected phase map after wavefront shaping using a full-phase modulation device in this embodiment of the invention, where a represents the corrected light intensity map and b represents the corrected phase map.

[0033] Figure 6 This embodiment of the invention uses a full-phase modulation device to perform wavefront shaping, and after phase matching, the light intensity distribution map and the corresponding corrected phase map are shown, where a represents the corrected light intensity map and b represents the corrected phase map.

[0034] Figure 7 These are the light intensity distribution map and the corresponding corrected wavefront map after wavefront shaping using a binarized modulation device in this embodiment of the invention, where a represents the corrected light intensity map and b represents the corrected phase map.

[0035] Figure 8 The images shown in this embodiment of the invention are wavefront shaping using a binarized modulation device, and the light intensity distribution map and the corresponding corrected wavefront map after phase matching, where a represents the corrected light intensity map and b represents the corrected phase map.

[0036] Figure 2 In the image, 1. Laser source; 2. First beam expander; 3. Spatial light modulator; 4. Rotating mask; 5. Second beam expander; 6. First objective lens; 7. Scattering medium; 8. Second objective lens; 9. Tube lens; 10. Photodetector. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below with reference to the accompanying drawings.

[0038] like Figure 2 As shown, the wavefront shaping system includes a laser source 1, a first beam expander 2, a spatial light modulator 3, a rotating mask 4, a second beam expander 5, a first objective lens 6, a scattering medium 7, a second objective lens 8, a tube lens 9, and a photodetector 10 arranged sequentially along the optical path. The beam emitted by the laser source 1 passes through the first beam expander 2, then enters the spatial light modulator 3 for modulation, and after modulation, passes sequentially through the rotating mask 4, the second beam expander 5, and the first objective lens 6, then through the scattering medium 7, and then sequentially through the second objective lens 8 and the tube lens 9, before being collected by the photodetector 10. The spatial light modulator 3, the rotating mask 4, and the photodetector 10 are electrically connected to the control unit, which is used to drive and control the rotation of the rotating mask 4, control the modulation signal refresh of the spatial light modulator 3, and receive and process the electrical signals collected by the photodetector 10.

[0039] The scattering medium 7 is specifically a slice of mouse brain. The first beam expander 2 fills the spatial light modulator 3 with light, improving the utilization rate of the spatial light modulator, and the second beam expander 5 fills the front focal plane of the objective lens 6 with light. The tube lens 9 converges the light to obtain the final real image.

[0040] The spatial light modulator 3 is disposed on the front focal plane of the first objective lens 6, and the spatial light modulator 3 and the first objective lens 6 are arranged coaxially.

[0041] The rotating mask 4 has the same dimensions as the photosensitive area of ​​the spatial light modulator 3. The rotating mask 4 is divided into four sub-regions, only one of which is transparent, while the transmittance of the remaining sub-regions is ≤0.01%. The modulation surface of the spatial light modulator 3 is divided into four modulation regions, which spatially correspond one-to-one with the four sub-regions of the rotating mask 4. The rotating mask 4 is divided into 2×2 sub-regions. Using the geometric center (i.e., the center of the circle) of the rotating mask 4 as a reference, two mutually perpendicular straight lines divide the rotating mask 4 into four equal-area sub-regions.

[0042] The scattering medium 7 is positioned in front of the focal plane of the first objective lens 6; the photodetector 10 is positioned on the focal plane of the tube lens 9, and the photodetector 10 and the tube lens 9 are arranged coaxially. The first objective lens 6 and the second objective lens 8 are conjugates, and the first objective lens 6 and the second objective lens 8 are arranged coaxially, with their focal points coinciding; the second objective lens 8 and the tube lens 9 are conjugates, and the second objective lens 8 and the tube lens 9 are arranged coaxially, with their focal points coinciding.

[0043] The spatial light modulator 3 is one of a full-phase spatial light modulator, a ferroelectric liquid crystal binarized phase-type spatial light modulator, or a digital micromirror; the photodetector 10 is one of a photomultiplier tube, an avalanche photodiode, or a silicon-based photodetector.

[0044] like Figure 1 As shown, the wavefront shaping method of the wavefront shaping system based on spatial segmentation and multiplexing includes the following steps:

[0045] S1. The laser light source 1 emits a beam, which is expanded by the first beam expander 2 and then enters the spatial light modulator 3.

[0046] S2. Configure the rotation period of the rotating mask 4 through the control unit to coordinate it with the refresh period of the spatial light modulator 3.

[0047] Specifically, the rotation period of the rotating mask 4 is configured such that the period of the rotating mask 4 completing a 360° rotation does not exceed the refresh period of the spatial light modulator 3. Within one complete rotation period of the rotating mask 4, each sub-region sequentially enters the optical path.

[0048] S3. During one refresh cycle of the spatial light modulator 3, the control unit drives the rotating mask 4 to rotate, so that the four sub-regions sequentially enter the optical path. For each sub-region that enters the optical path, the beam wavefront (phase or amplitude) is modulated by the modulation region corresponding to that sub-region. After the modulated beam is transmitted, it is collected by the photodetector 10 and converted into a set of electrical signals, thereby obtaining four sets of electrical signals in sequence and transmitting them to the control unit.

[0049] Specifically, within one refresh cycle of the spatial light modulator 3, the control unit drives the rotating mask 4 to rotate, so that the four sub-regions sequentially enter the optical path. For each sub-region that enters the optical path, the beam wavefront (phase or amplitude) is modulated by the modulation region corresponding to that sub-region in the spatial light modulator 3. The modulated beam sequentially passes through the second beam expander 5, the first objective lens 6, the scattering medium 7, the second objective lens 8, and the tube lens 9 before being collected by the photodetector 10 and converted into a corresponding set of electrical signals, thereby obtaining four sets of electrical signals in sequence and transmitting them to the control unit.

[0050] S4 and the rear control unit sequentially process the four sets of electrical signals obtained by using the wavefront shaping algorithm to obtain four sets of preliminary correction wavefront parameters. The preliminary correction wavefront parameters are specifically phase or amplitude parameters. The wavefront shaping algorithm is one of the transfer matrix algorithm, genetic algorithm or coherent optical adaptive technology.

[0051] S5. Remove the rotating mask so that the beams from all four sub-regions are collected by the photodetector. Wavefront matching is then performed sequentially on the four preliminary correction wavefronts to obtain a complete correction wavefront (phase or amplitude). This final complete wavefront serves as the modulation signal in the spatial light modulator 3. Wavefront matching: While keeping the wavefront distribution of one sub-region unchanged, the wavefront distribution parameters of the other three sub-regions are sequentially inverted, and iterative optimization is performed based on the signal from the photodetector 10 to maximize the light intensity signal. Example 1:

[0052] like Figure 2 As shown, the light emitted by the laser source 1 passes through the first beam expander 2, enters the spatial light modulator 3, is modulated, passes through the rotating mask 4, passes through the second beam expander 5, enters the first objective lens 6, passes through the scattering medium 7, passes through the second objective lens 8 and the tube lens 9, and is finally received by the photodetector 10.

[0053] In this configuration, the spatial light modulator 3 is coaxially arranged on the front focal plane of the first objective lens 6. The rotating mask 4 has the same size as the photosensitive size of the spatial light modulator 3, and is divided into 2×2 sub-regions, of which only one sub-region is transparent, and the transmittance of the other three sub-regions is ≤0.01%. The first objective lens 6 and the second objective lens 8 are conjugates, coaxially arranged, and their focal points coincide. The scattering medium 7 is located in front of the focal plane of the first objective lens 6. The second objective lens 8 and the tube lens 9 are conjugates, coaxially arranged, and their focal points coincide. The photodetector 10 is on the focal plane of the tube lens 9, and the photodetector 10 and the tube lens 9 are coaxially arranged. The photodetector 10 is a silicon-based photodetector, and the spatial light modulator 3 is a full-phase spatial light modulator.

[0054] Laser source 1 emits laser light, which is expanded by first beam expander 2 to make the beam diameter the same as the photosensitive surface of spatial light modulator 3. For example, the beam diameter is expanded from 2mm to approximately 8mm. After being modulated by spatial light modulator 3, the beam passes through rotating mask 4 and then through second beam expander 5, expanding the beam diameter to the entrance aperture of first objective lens 6. For example, the beam diameter is expanded from 8mm to approximately 10mm. The beam penetrates the conjugate objective lens pair (first objective lens and second objective lens), and the scattering medium 7 is in front of the focal plane of first objective lens 6. The beam is then focused onto photodetector 10 after passing through tube lens 9, which is conjugate with second objective lens 8. Laser source 1 is emitted by a laser, which can be a Changchun New Industries MGL-FN-589-500mW laser. Spatial light modulator 3 can be a Meadowlark Optics E-Series-1920x1200, 400-800nm ​​laser. Silicon-based photodetectors can be Thorlabs' PDA100A2, 320-1100nm.

[0055] Within the same period, the spatial light modulator 3 is divided into four 2×2 sub-regions. A modulation phase is applied to each of the four sub-regions within the spatial light modulator 3, and simultaneously, a silicon-based photodetector is triggered to acquire the modulated optical signal.

[0056] The spatial light modulator has a refresh rate of 60Hz. After each quarter cycle, the rotating mask 4 rotates 90 degrees, allowing the modulated light from one sub-region to pass through the mask and enter the silicon-based photodetector. When passing through the scattering medium 7, the diameter of the scattered beam exceeds the aperture of the mask, and the excess is filtered out, equivalent to a low-frequency spatial filter, which slightly reduces the correction effect. Finally, the optical signals collected by the silicon-based photodetector are the modulated light intensity values ​​of different sub-regions, that is, four sets of sub-region signals are collected within one spatial light modulator cycle. According to the rotation direction and timing of the rotating mask 4, the signals can be divided into four groups, each corresponding to the feedback signal of a sub-region. For the four different sub-regions, coherent optical adaptive technology is applied to achieve simultaneous correction of the sub-regions.

[0057] The rotating mask is removed, allowing the modulated light to be received entirely by the silicon-based photodetector. Wavefront matching is then performed on the correction wavefront signals from four different regions to obtain the final correction wavefront. This wavefront signal is now a phase signal. Specifically, the phase of one sub-region is kept constant, while the phases of other regions are sequentially changed. The original phase value is then added to the phase value of the sub-region to obtain a new phase, which is then applied to the corresponding sub-region of the spatial light modulator. The phase is iterated using the signal from the silicon-based photodetector as a feedback signal to maximize the light intensity signal.

[0058] like Figure 4 The image in the middle is a speckle pattern at the focal plane of the first objective lens 6 after passing through the scattering medium 7. Figure 4 In the diagram, 'a' is the speckle pattern obtained after removing the rotating mask. Figure 4 In the image, b, c, d, and e are speckle patterns obtained after the four sub-regions (top, bottom, left, and right) pass through the mask sequentially following the rotational mask 4. Figure 4 It can be seen that after the scattering signal is modulated by the mask, the speckle pattern obtained in each sub-region will lose a portion of the light intensity energy.

[0059] Figure 5 It is a corrected intensity map obtained by sequentially performing wavefront shaping algorithm on four sub-regions. Figure 5 a) and the corrected phase diagram ( Figure 5 (b) In this case, the central region of the image is magnified to more clearly observe the light field distribution. It can be seen from the image that phase matching was not performed, and the maximum value of the resulting light spot is not in the very center region, showing a significant offset.

[0060] Figure 6 The final corrected intensity map is obtained after wavefront matching of four sub-regions. Figure 6 a) and the corrected phase diagram ( Figure 6 (b) In this example, the central region of the image is magnified to more clearly observe the light field distribution. The image shows that after wavefront matching, the maximum light intensity is located at the center of the image, and the intensity distribution is more concentrated. Example 2:

[0061] like Figure 2 As shown, the light emitted by the laser source 1 passes through the first beam expander 2, enters the spatial light modulator 3, is modulated, passes through the rotating mask 4, passes through the second beam expander 5, enters the first objective lens 6, passes through the scattering medium 7, passes through the second objective lens 8 and the tube lens 9, and is finally received by the photodetector 10.

[0062] In this configuration, the spatial light modulator 3 is coaxially arranged on the front focal plane of the first objective lens 6. The rotating mask 4 has the same size as the photosensitive size of the spatial light modulator 3, and is divided into 2×2 sub-regions, of which only one sub-region is transparent, and the transmittance of the other three sub-regions is ≤0.01%. The first objective lens 6 and the second objective lens 8 are conjugates, coaxially arranged, and their focal points coincide. The scattering medium 7 is located in front of the focal plane of the first objective lens 6. The second objective lens 8 and the tube lens 9 are conjugates, coaxially arranged, and their focal points coincide. The photodetector 10 is on the focal plane of the tube lens 9, and the photodetector 10 and the tube lens 9 are coaxially arranged. The photodetector 10 is a silicon avalanche photodetector, and the spatial light modulator 3 is a ferroelectric liquid crystal binarized spatial light modulator.

[0063] Laser source 1 emits laser light, which is expanded by first beam expander 2 to make the beam diameter the same as the photosensitive surface of spatial light modulator 3. For example, the beam diameter is expanded from 2 mm to about 8 mm. After being modulated by spatial light modulator 3, the beam passes through rotating mask 4 and then through second beam expander 5, expanding the beam diameter to the entrance aperture of first objective lens. For example, the beam diameter is expanded from 8 mm to about 10 mm. The beam penetrates the conjugate objective lens pair (first objective lens and second objective lens), the scattering medium 7 is in front of the focal plane of first objective lens 6, and the beam is focused onto silicon avalanche photodetector 10 after passing through tube lens 9 conjugate with second objective lens 8. Laser source 1 is emitted by a laser, which can be Changchun New Industries MGL-FN-589-500mW. Spatial light modulator 3 can be A512-0532-P8 from Meadowlark Optics, USA, 400-800nm. Silicon avalanche photodetector can be APD431A from Thorlabs, USA, 400-1000nm.

[0064] Within the same period, the spatial light modulator 3 is divided into four 2×2 sub-regions. A modulation phase is applied to each of the four sub-regions within the spatial light modulator 3, and the silicon avalanche photodetector is simultaneously triggered to acquire the modulated optical signal.

[0065] The ferroelectric liquid crystal binarized spatial light modulator has a refresh rate of 1000Hz. After each quarter cycle, the rotating mask 4 rotates 90 degrees, allowing the modulated light from another sub-region to pass through the mask and enter the optical path, ultimately being received by the silicon avalanche photodetector. The optical signals collected by the silicon avalanche photodetector are the light intensity values ​​obtained after modulation of the light field in different sub-regions, meaning that four sets of sub-region signals are collected within one spatial light modulator cycle. Based on the rotation direction and timing of the rotating mask 4, the signals can be divided into four groups, each corresponding to the light intensity signal of a sub-region. For the four different sub-regions, a genetic algorithm is applied, using the collected light intensity signals from different sub-regions as feedback information to achieve simultaneous correction of the four sub-regions.

[0066] The rotating mask is removed, allowing all modulated light to be received by the silicon avalanche photodetector. Wavefront matching is performed on the correction wavefront signals from four different regions to obtain the final correction wavefront, where the wavefront signal is the phase signal. Specifically, the phase of one sub-region is kept constant, while the phases of other regions are changed sequentially. The original phase value is added to the phase value of the sub-region to obtain the new phase, which is then applied to the corresponding sub-region of the spatial light modulator. The signal from the silicon avalanche photodetector is used as a feedback signal to iterate the phase, maximizing the light intensity signal.

[0067] like Figure 4 The image in the middle is the speckle pattern at the focal plane of the first objective lens after passing through the scattering medium. Figure 4In the diagram, 'a' represents the speckle pattern obtained after removing the rotating mask. Figure 4 In the image, b, c, d, and e are speckle patterns obtained after the four sub-regions (top, bottom, left, and right) are sequentially passed through the rotating mask 4. From... Figure 4 It can be seen that after the scattering signal is modulated by the rotating mask 4, the speckle pattern obtained in each sub-region will lose a portion of the light intensity energy.

[0068] Figure 7 It is a corrected intensity map obtained by sequentially performing wavefront shaping algorithm on four sub-regions. Figure 7 a) and the corrected phase diagram ( Figure 7 (b) In this example, the central region of the image is magnified to more clearly observe the light field distribution. The image shows that the wavefront was not matched, and the maximum value of the resulting light spot is not in the very center region, exhibiting a significant offset.

[0069] Figure 8 The final corrected intensity map is obtained after wavefront matching of four sub-regions. Figure 8 a) and the corrected phase diagram ( Figure 8 (b) In this method, the central region of the image is magnified to more clearly observe the distribution of the light field. From Figure 8 It can be seen that after wavefront matching, the maximum light intensity is located in the center of the image, and the intensity distribution is more concentrated. Example 3:

[0070] like Figure 2 As shown, the light emitted by the laser source 1 passes through the first beam expander 2, enters the spatial light modulator 3, is modulated, passes through the rotating mask 4, passes through the second beam expander 5, enters the first objective lens 6, passes through the scattering medium 7, passes through the second objective lens 8 and the tube lens 9, and is finally received by the photodetector 10.

[0071] In this configuration, the spatial light modulator 3 is coaxially arranged on the front focal plane of the first objective lens 6. The rotating mask 4 has the same size as the photosensitive size of the spatial light modulator 3, and is divided into 2×2 sub-regions, of which only one sub-region is transparent, and the transmittance of the other three sub-regions is ≤0.01%. The first objective lens 6 and the second objective lens 8 are conjugates, coaxially arranged, and their focal points coincide. The scattering medium 7 is located in front of the focal plane of the first objective lens 6. The second objective lens 8 and the tube lens 9 are conjugates, coaxially arranged, and their focal points coincide. The photodetector 10 is on the focal plane of the tube lens 9, and the photodetector 10 and the tube lens 9 are coaxially arranged. The photodetector 10 is a photomultiplier tube, and the spatial light modulator 3 is a digital micromirror.

[0072] Laser source 1 emits laser light, which is expanded by first beam expander 2 to make the beam diameter the same as the photosensitive surface of spatial light modulator 3. For example, the beam diameter is expanded from 2mm to about 8mm. After being modulated by spatial light modulator 3, the beam passes through mask 4 and then second beam expander 5, expanding the beam diameter to the entrance aperture of first objective lens 6. For example, the beam diameter is expanded from 8mm to about 10mm. The beam penetrates the conjugate objective lens pair (first objective lens and second objective lens), the scattering medium 7 is in front of the focal plane of the first objective lens, and the beam is focused onto photomultiplier tube 10 after passing through tube lens 9 conjugate with second objective lens 8. Laser source 1 is emitted by a laser, which can be Changchun New Industries MGL-FN-589-500mW, spatial light modulator 3 can be ViALUX V-9501 (400-700nm) from Germany, and photomultiplier tube can be Hamamatsu H7422P-40 (300-720nm) from Japan.

[0073] Within the same period, the spatial light modulator 3 is divided into four 2×2 sub-regions. Modulation signals are applied to the four sub-regions within the spatial light modulator 3, and photomultiplier tubes are simultaneously triggered to acquire the modulated optical signals.

[0074] The refresh rate of the digital micromirror can reach over 1000Hz. After each quarter cycle, the rotating mask 4 rotates 90 degrees, allowing the modulated light from another sub-region to pass through the rotating mask 4 and enter the photomultiplier tube. Finally, the photomultiplier tube collects light signals representing the intensity values ​​obtained after light field modulation in different sub-regions. That is, within one spatial light modulator cycle, four sets of sub-region signals are acquired. Based on the rotation direction of the rotating mask 4 and the timing of the signals, the signals can be divided into four groups, each corresponding to the feedback signal of a sub-region. For the four different sub-regions, transfer matrix technology is applied, using the feedback light intensity signals for iterative correction to achieve simultaneous correction of multiple sub-regions.

[0075] The rotating mask is removed, allowing all modulated light to be received by the photomultiplier tube. Wavefront matching is performed on the correction wavefront signals from four different regions to obtain the final correction wavefront, where the wavefront signal is the amplitude signal. Specifically, the amplitude parameters of one sub-region are kept constant, while the amplitude parameters of other regions are sequentially reversed, changing the 'on' micromirrors to the 'off' state and vice versa. The photomultiplier tube signal is used as feedback to iterate the amplitude, maximizing the light intensity signal.

[0076] like Figure 4 The image in the middle is the speckle pattern at the focal plane of the first objective lens after passing through the scattering medium. Figure 4 In the diagram, 'a' is the speckle pattern obtained after removing the rotating mask. Figure 4In the image, b, c, d, and e are speckle patterns obtained after the four sub-regions (top, bottom, left, and right) are sequentially passed through the rotating mask 4. From... Figure 4 It can be seen that after the scattering signal is modulated by the rotating mask 4, the speckle pattern obtained in each sub-region will lose a portion of the light intensity energy.

[0077] Figure 7 It is a corrected intensity map obtained by sequentially performing wavefront shaping algorithm on four sub-regions. Figure 7 a) and corrected wavefront diagram ( Figure 7 (b) In this image, the central region is magnified to more clearly observe the light field distribution. From this image, it can be seen that the wavefront was not matched, and the maximum value of the resulting light spot is not in the very center region, showing a significant offset.

[0078] Figure 8 The final corrected intensity map is obtained after wavefront matching of four sub-regions. Figure 8 a) and corrected wavefront diagram ( Figure 8 (b) In this image, the central region is magnified to more clearly observe the light field distribution. This image shows that after wavefront matching, the maximum light intensity is located at the center of the image, and the intensity distribution is more concentrated.

[0079] In summary, the effectiveness of this invention in improving wavefront shaping and focusing is evident. Furthermore, those skilled in the art will understand that the above description is merely a preferred embodiment of the invention and is not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A wavefront shaping system based on spatial segmentation and multiplexing, characterized in that: The system includes a laser source (1), a first beam expander (2), a spatial light modulator (3), a rotating mask (4), a second beam expander (5), a first objective lens (6), a scattering medium (7), a second objective lens (8), a tube lens (9), and a photodetector (10) arranged sequentially along the optical path. The beam emitted by the laser source (1) passes through the first beam expander (2), then enters the spatial light modulator (3) for modulation, and after modulation, passes sequentially through the rotating mask (4), the second beam expander (5), the first objective lens (6), then through the scattering medium (7), then sequentially through the second objective lens (8) and the tube lens (9), and is finally collected by the photodetector (10). The size of the rotating mask (4) is consistent with the photosensitive size of the spatial light modulator (3). The rotating mask (4) is divided into four sub-regions, of which only one sub-region is transparent and the transmittance of the remaining sub-regions is ≤0.01%. The modulation surface of the spatial light modulator (3) is divided into four sub-modulation regions, and the four sub-modulation regions correspond one-to-one with the four sub-regions of the rotating mask (4) in space. The rotating mask (4) is divided into 2×2 sub-regions. Based on the geometric center of the rotating mask (4), the rotating mask (4) is divided into four sub-regions of equal area by two mutually perpendicular straight lines.

2. The wavefront shaping system based on spatial segmentation and multiplexing according to claim 1, characterized in that: The spatial light modulator (3) is disposed on the front focal plane of the first objective lens (6), and the spatial light modulator (3) and the first objective lens (6) are arranged coaxially.

3. The wavefront shaping system based on spatial segmentation and multiplexing according to claim 1, characterized in that: The scattering medium (7) is placed in front of the focal plane of the first objective lens (6); the photodetector (10) is placed on the focal plane of the tube lens (9), and the photodetector (10) and the tube lens (9) are arranged coaxially.

4. The wavefront shaping system based on spatial segmentation and multiplexing according to claim 1, characterized in that: The first objective lens (6) is conjugate with the second objective lens (8), and the first objective lens (6) and the second objective lens (8) are arranged coaxially, with the focal points of the first objective lens (6) and the second objective lens (8) coinciding; the second objective lens (8) is conjugate with the tube lens (9), and the second objective lens (8) and the tube lens (9) are arranged coaxially, with the focal points of the second objective lens (8) and the tube lens (9) coinciding.

5. A wavefront shaping system based on spatial segmentation and multiplexing according to claim 1, characterized in that: The spatial light modulator (3) is one of a full-phase spatial light modulator, a ferroelectric liquid crystal binarized phase-type spatial light modulator, or a digital micromirror; the photodetector (10) is one of a photomultiplier tube, an avalanche photodiode, or a silicon-based photodetector.

6. A wavefront shaping method for a wavefront shaping system based on spatial segmentation and multiplexing as described in any one of claims 1-5, characterized in that, The method includes the following steps: S1. The laser light source (1) emits a beam, which is expanded by the first beam expander (2) and then enters the spatial light modulator (3). S2. Configure the rotation period of the rotating mask (4) by the control unit to coordinate it with the refresh period of the spatial light modulator (3); S3. During one refresh cycle of the spatial light modulator (3), the control unit drives the rotating mask (4) to rotate, so that the four sub-regions are sequentially turned into the optical path. For each sub-region turned into the optical path, the beam wavefront is modulated by the sub-modulation region corresponding to the sub-region. The modulated beam is then transmitted and collected by the photodetector (10) and converted into a set of signals, thereby obtaining four sets of signals in sequence and transmitting them to the control unit. S4. The control unit sequentially processes the four sets of signals using the wavefront shaping algorithm to obtain four sets of preliminary correction wavefront parameters, which are specifically phase or amplitude parameters. S5. Remove the rotating mask so that the beams of the four sub-regions are collected by the photodetector (10). Perform wavefront matching on the four preliminary correction wavefronts in sequence to obtain a complete correction wavefront. The final complete wavefront is used as the modulation signal in the spatial light modulator (3).

7. The wavefront shaping method according to claim 6, characterized in that, Steps S2-S3 are specifically as follows: S2. Set the rotation period of the rotating mask (4) so ​​that the period time for the rotating mask (4) to complete a 360° rotation does not exceed the refresh period time of the spatial light modulator (3). During one complete rotation period of the rotating mask (4), each of the sub-regions sequentially enters the optical path. S3. During one refresh cycle of the spatial light modulator (3), the control unit drives the rotating mask (4) to rotate, so that the four sub-regions sequentially enter the optical path. For each sub-region that enters the optical path, the beam wavefront is modulated by the sub-modulation region corresponding to the sub-region in the spatial light modulator (3). The modulated beam sequentially passes through the second beam expander (5), the first objective lens (6), the scattering medium (7), the second objective lens (8), and the tube lens (9) before being collected by the photodetector (10) and converted into a corresponding set of signals, thereby obtaining four sets of signals in sequence and transmitting them to the control unit.

8. The wavefront shaping method according to claim 7, characterized in that: In step S4, the wavefront shaping algorithm is one of the transfer matrix algorithm, genetic algorithm or coherent optical adaptive technology; in step S5, the wavefront matching is: keeping the wavefront distribution of one sub-region unchanged, reversing the wavefront distribution parameters of the other three sub-regions in turn, and iteratively optimizing based on the signal of the photodetector (10).

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