A holographic wavefront shaping system and method based on Fourier encoding and decoding

Abstract

The present invention discloses a holographic wavefront shaping system and method based on Fourier encoding and decoding. In the encoding process, the present invention realizes frequency domain multiplexing of multiple wavefronts by corresponding each wavefront to gratings of different spatial frequencies; in the decoding process, the present invention deflects the focused light spot generated by the coded wavefront on the Fourier plane through the tilted phase generated by the scanning device, and decodes the coded wavefront located at the optical axis through the pinhole of the focal plane. The present invention realizes the rapid switching of complex wavefronts by combining the characteristics of fast response speed of the scanning device and high modulation dimension of the spatial light modulator, thereby greatly improving the speed of wavefront shaping.

Description

Technical Field

[0001] The present invention relates to a wavefront shaping system and method in the field of wavefront shaping, and in particular to a holographic wavefront shaping system and method based on Fourier encoding and decoding. Background Art

[0002] Wavefront shaping methods are widely used in various optical fields. They have great advantages in improving the performance of optical systems, solving complex imaging problems, and enhancing laser processing accuracy. Wavefront shaping uses advanced modulation methods to precisely manipulate the phase and amplitude of light waves to obtain the required light field distribution. In super-resolution imaging, wavefront shaping methods can effectively improve resolution and imaging quality by generating structured light and controlling point spread functions. In scattering medium imaging, wavefront shaping methods can achieve diffraction-limited focusing behind scattering media; in adaptive optical systems, wavefront shaping methods can be used to compensate for phase distortion caused by atmospheric turbulence and biological samples, and improve the imaging quality of astronomical and microscopic systems.

[0003] Although wavefront shaping methods are widely used, the wavefront response speed is still an important factor restricting the development of technology. Traditional wavefront shaping devices include liquid crystal-based spatial light modulators, physical deformation-based deformable mirrors, and DMDs based on micro-opto-electromechanical systems. The physical characteristics of these wavefront shaping devices limit the wavefront response time to the Khz level. In some applications that require faster wavefront shaping, traditional wavefront shaping devices will no longer be applicable. In addition to these wavefront shaping devices, there are also shaping devices based on plasma phase modulation, grating light valves based on micro-electromechanical systems, and wavefront shaping devices based on photorefractive crystals. Among them, the shaping device based on plasma phase modulation can increase the wavefront response speed to the Ghz level, but the number of modulation modes is too low to be applied in specific experiments. The grating light valve based on micro-electromechanical systems can increase the wavefront response speed to 350Khz, but can only achieve one-dimensional light field modulation. The wavefront shaping device based on photorefractive crystals can increase the response speed to the same speed as the propagation of light pulses, but the application scenarios cannot be well expanded and are now only used for phase conjugation.

[0004] Therefore, there is an urgent need for a wavefront shaping system that has both strong wavefront modulation capability and short wavefront response time. Summary of the invention

[0005] In order to solve the problems and needs in the background technology, the present invention proposes a holographic wavefront shaping system and method based on Fourier encoding and decoding. The present invention realizes Fourier coded multiplexing wavefront by loading different wavefronts to be encoded in different frequency domains. During the decoding process, after scanning by the scanning device and Fourier transformation of the lens, the coded light spots in different frequency domains are deflected to the pinhole to realize the selection of a specific wavefront. The present invention combines the fine wavefront modulation capability of the spatial light modulator and the fast response characteristics during scanning to achieve fast complex wavefront response.

[0006] 1. A holographic wavefront shaping system based on Fourier encoding and decoding

[0007] The holographic wavefront shaping system based on Fourier encoding and decoding includes a wavefront encoding component and a wavefront decoding component. The wavefront encoding component is used to obtain an encoded light beam after Fourier encoding the input light beam, and the encoded light beam is incident on the wavefront decoding component. The wavefront decoding component is used to perform Fourier decoding on the incident encoded light beam to obtain a shaped wavefront distribution.

[0008] Furthermore, the wavefront coding component includes a spatial light modulator, a first 4f system and a scanning device, wherein the spatial light modulator is conjugated with the scanning device through the first 4f system, wherein the spatial light modulator is used to generate a Fourier-coded multiplexed wavefront, the first 4f system is used to adjust the light beam size so that the spatial light modulator and the scanning device are conjugated and the light beam size matches, and the scanning device is used to generate a tilted phase so that the encoded light beam selectively decodes a specific wavefront after passing through the wavefront decoding component.

[0009] Furthermore, the input light beam is incident on the wavefront decoding component after passing through the spatial light modulator, the first 4f system and the scanning device in sequence, or the input light beam is incident on the wavefront decoding component after passing through the scanning device, the first 4f system and the spatial light modulator in sequence.

[0010] Furthermore, the wavefront decoding component includes a second 4f system and a pinhole, wherein the pinhole is located at the Fourier transform of the second 4f system. At the plane, The coded light beam only allows the coded light spot located at the optical axis to pass through the pinhole, wherein the second 4f system is used to perform Fourier transform and inverse transform on the coded light beam, and the pinhole is used for filtering.

[0011] Furthermore, the spatial light modulator is one of a phase-type spatial light modulator, an amplitude-type spatial light modulator, a DMD, a metasurface, and a DOE device;

[0012] Furthermore, the scanning device is one of a reflector, a galvanometer, an electro-optical deflector, and an acousto-optical deflector.

[0013] Furthermore, the first 4f system includes a first lens and a second lens.

[0014] Furthermore, the second 4f system includes a third lens and a fourth lens, a pinhole is placed between the third lens and the fourth lens, and the pinhole is coaxially arranged with the third lens and the fourth lens.

[0015] 2. A holographic wavefront shaping method based on Fourier encoding and decoding

[0016] 1) The coded wavefront is obtained by using the method that all the wavefronts to be coded correspond to gratings of different spatial frequencies, and the coded wavefront is loaded on the wavefront coding component. When the input light beam passes through the wavefront coding component, a coded light beam is obtained; in the coded light beam, the coded light spots formed by different coded wavefronts are distributed at different spatial positions on the Fourier plane of the second 4f system;

[0017] 2) During the decoding process, a coded spot array is formed at the Fourier plane of the second 4f system, and tilted phases of different spatial frequencies are generated by the scanning device in the wavefront coding component. After each tilted phase is superimposed on the corresponding coded wavefront, the corresponding coded spot in the spot array is deflected and then passes through the second 4f system and the pinhole, finally completing the decoding of the specific wavefront and obtaining the decoded wavefront distribution, that is, the shaped wavefront distribution.

[0018] Furthermore, in 1), the grating is one of a blazed grating and a Dammann grating;

[0019] Furthermore, the distribution of the coded light spot on the Fourier plane of the second 4f system is one of equally spaced distribution, equally spaced distribution along a circle, and adaptive distribution according to a spectrum range of the coded wavefront.

[0020] Furthermore, in 1), the method for obtaining the coded wavefront is one of the following methods: summing the complex amplitudes of all the wavefronts to be coded after superposition with the corresponding grating and taking the phase part, and generating a holographic image with a computer.

[0021] Furthermore, in 2), the scanning method of the scanning device is one of continuous scanning and random scanning.

[0022] Furthermore, in 2), the size of the pinhole is one of the maximum spectrum size of the multiplexed wavefront and the spectrum multiplexing interval.

[0023] The present invention includes a mutually conjugated spatial light modulator, a scanning device, and a pinhole located at the Fourier plane of the second 4f system. The input light beam passes through the spatial light modulator and the scanning device and undergoes Fourier transformation through a lens; finally, the shaped light beam is obtained after passing through the focal plane pinhole and the Fourier inverse transformation through the lens; the spatial light modulator is used to generate a Fourier-coded multiplexed wavefront; the scanning device is used to quickly generate an inclined phase and deflect the coded light spot; the pinhole is used to filter out the light spot outside a certain spectrum range at the optical axis for the selection of the coded wavefront. In the encoding process, the frequency domain multiplexing of multiple wavefronts is achieved by corresponding each wavefront to a grating of different spatial frequencies; in the decoding process, the focused light spot generated by the coded wavefront is deflected on the Fourier plane of the second 4f system through the inclined phase generated by the scanning device, and the coded wavefront located at the optical axis is decoded through the pinhole of the Fourier plane of the second 4f system. The present invention realizes the rapid switching of complex wavefronts by combining the characteristics of fast response speed of the scanning device and high modulation dimension of the spatial light modulator, which greatly improves the speed of wavefront shaping.

[0024] The beneficial effects of the present invention are:

[0025] The present invention combines the high modulation dimension of the spatial light modulator with the fast response speed of the scanning device, and achieves the effect of quickly switching complex wavefronts through Fourier encoding wavefront, scanning device deflection and pinhole decoding wavefront, which greatly improves the wavefront response speed of the complex wavefront, and solves the problem in the prior art that it cannot have both strong wavefront modulation capability and short wavefront response time. It has great potential in the fields of imaging, communication, laser processing, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to explain the present invention in more detail and concretely, the following drawings are used for description. The drawings show the structure diagrams of two examples of the system of the present invention, and the component numbers are listed and explained accordingly;

[0027] Figure 1 It is a schematic diagram of the structure of the holographic wavefront shaping system of Example 1 of the present invention.

[0028] Figure 2 It is a schematic diagram of the structure of the holographic wavefront shaping system of Example 2 of the present invention.

[0029] Figure 3 It is a schematic diagram of wavefront Fourier encoding.

[0030] Figure 4 It is the Fourier transform process of the coded wavefront.

[0031] Figure 5 This is a schematic diagram of the Fourier decoding process.

[0032] In the figure: spatial light modulator 1, first lens 2, second lens 3, scanning device 4, third lens 5, pinhole 6, fourth lens 7. DETAILED DESCRIPTION

[0033] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0034] The embodiments of the present invention and the specific process thereof are as follows: Example 1

[0035] like Figure 1 As shown, the holographic wavefront shaping system based on Fourier encoding and decoding includes a wavefront encoding component and a wavefront decoding component. The wavefront encoding component is used to perform Fourier encoding on the input light beam to obtain an encoded light beam, and the encoded light beam is incident on the wavefront decoding component; the wavefront decoding component is used to perform Fourier decoding on the incident encoded light beam to obtain a shaped wavefront distribution.

[0036] The wavefront coding component includes a spatial light modulator 1, a first 4f system and a scanning device 4. The spatial light modulator 1 is conjugated with the scanning device 4 through the first 4f system, that is, the spatial light modulator 1 is conjugated with the scanning device 4, wherein the spatial light modulator 1 is used to generate a Fourier-coded multiplexed wavefront, the first 4f system is used to adjust the light beam size so that the spatial light modulator 1 and the scanning device 4 are conjugated and the light beam size matches, and the scanning device 4 is used to generate a tilted phase so that the encoded light beam passes through the wavefront decoding component and selectively decodes a specific wavefront.

[0037] The input light beam is incident into the wavefront decoding component after passing through the spatial light modulator 1, the first 4f system and the scanning device 4 in sequence. The first 4f system comprises a first lens 2 and a second lens 3 arranged along the optical axis, and the focal points of the first lens 2 and the second lens 3 coincide.

[0038] The wavefront decoding component includes a second 4f system and a pinhole 6, wherein the pinhole 6 is located at the Fourier transform of the second 4f system. At the plane, Only the coded light spot located at the optical axis in the coded light beam is allowed to pass through the pinhole 6, wherein the second 4f system is used to perform Fourier transform and inverse Fourier transform on the coded light beam, and the pinhole 6 is used for filtering.

[0039] The second 4f system includes a third lens 5 and a fourth lens 7 arranged along the optical axis, the focal points of the third lens 5 and the fourth lens 7 coincide with each other, and a Fourier transform between the third lens 5 and the fourth lens 7 is performed. Plane A pinhole 6 is disposed coaxially with the third lens 5 and the fourth lens 7 , wherein the third lens 5 is used for performing Fourier transform and the fourth lens 7 is used for performing inverse Fourier transform.

[0040] The spatial light modulator 1 is a phase-type spatial light modulator, and the scanning device 4 is specifically a galvanometer. The light beam first enters the phase-type spatial light modulator at a small angle, and after being reflected by the phase-type spatial light modulator, it passes through the first 4f system composed of the first lens 2 and the second lens 3 to be conjugated with the galvanometer. After passing through the galvanometer, it passes through the third lens 5 to reach the Fourier transform. flat , spatial filtering is performed by the pinhole 6. Finally, the fourth lens 7 is passed to obtain a shaped wavefront distribution.

[0041] The implementation process is as follows:

[0042] 1) The multiplexed wavefront is controlled by a phase-type spatial light modulator. The coded wavefront is obtained by matching 9 different zernike aberrations with blazed gratings of different spatial frequencies that are equally spaced in the frequency domain, and summing the complex amplitudes of all the coded wavefronts superimposed with the corresponding blazed gratings and taking the phase part. The coding process is as follows: Figure 3 As shown, Figure 3 The nine zernike aberrations and their multiplexed wavefront distribution after being equidistantly encoded in the frequency domain. The phase-type spatial light modulator can be 1920x1200, 850-1300nm from Meadowlark Optics of the United States.

[0043] 2) The modulated light beam passes through the first lens 2 and the second lens 3 to form a 4f system, the light beam size is controlled within the range of the galvanometer, and the galvanometer is conjugated with the spatial light modulator 1 to ensure the effectiveness of the galvanometer tilt phase compensation. The galvanometer can be the 6215h galvanometer of CTI of the United States.

[0044] 3) The light beam passing through the galvanometer is focused by the third lens 5, and the Fourier Plane (i.e. Focal plane ） The light intensity distribution at is the Fourier transform of the light field at the galvanometer. Figure 4 is the intensity distribution of the coded wavefront and the focal plane. The larger the corresponding grating spatial frequency in the coded wavefront, the farther the coded light spot is from the optical axis.

[0045] 4) The pinhole 6 located at the focal plane filters out the coded light spots exceeding a certain spatial frequency, such as Figure 5 As shown, the white circle is the light transmission range of the pinhole 6, that is, the center circle is the light transmission pinhole. The light passing through the pinhole 6 passes through the fourth lens 7 and is Fourier transformed again to obtain the decoded wavefront. Figure 5 As shown, by scanning the galvanometer (i.e., changing the displacement of the coded light spot in the X and Y directions) and the tilt phase of the opposite spatial frequency of the loaded grating, different coded light spots can be deflected to the pinhole 6 and different wavefronts can be decoded. Example 2

[0046] like Figure 2As shown, the holographic wavefront shaping system based on Fourier encoding and decoding includes a wavefront encoding component and a wavefront decoding component. The wavefront encoding component is used to obtain an encoded light beam after Fourier encoding the input light beam, and the encoded light beam is incident on the wavefront decoding component. The wavefront decoding component is used to perform Fourier decoding on the incident encoded light beam to obtain a shaped wavefront distribution.

[0047] The wavefront coding component includes a spatial light modulator 1, a first 4f system and a scanning device 4, wherein the scanning device 4 is conjugated with the spatial light modulator 1 through the first 4f system, that is, the spatial light modulator 1 is conjugated with the scanning device 4, wherein the spatial light modulator 1 is used to generate a multiplexed wavefront, the first 4f system is used to adjust the light beam size so that the light beam sizes in the spatial light modulator 1 and the scanning device 4 are the same, and the scanning device 4 is used to generate an inclined phase so that the encoded light beam can selectively decode a specific wavefront after passing through the wavefront decoding component.

[0048] The input light beam is incident into the wavefront decoding component after passing through the scanning device 4, the first 4f system and the spatial light modulator 1. The first 4f system comprises a first lens 2 and a second lens 3 arranged along the optical axis, and the focal points of the first lens 2 and the second lens 3 coincide.

[0049] The wavefront decoding component includes a second 4f system and a pinhole 6, wherein the pinhole 6 is located at the Fourier transform of the second 4f system. At the plane, Only the coded light spot located at the optical axis in the coded light beam is allowed to pass through the pinhole 6, wherein the second 4f system is used to perform Fourier transform and inverse transform on the coded light beam, and the pinhole 6 is used for filtering.

[0050] The second 4f system includes a third lens 5 and a fourth lens 7 arranged along the optical axis, the focal points of the third lens 5 and the fourth lens 7 coincide, a pinhole 6 is placed between the third lens 5 and the fourth lens 7, and the pinhole 6 is coaxially arranged with the third lens 5 and the fourth lens 7, wherein the third lens 5 is used for performing Fourier transform, and the fourth lens 7 is used for performing inverse Fourier transform.

[0051] The spatial light modulator 1 is a phase-type spatial light modulator, and the scanning device 4 is specifically an acousto-optic deflector. The light beam first enters the acousto-optic deflector at the Brewster angle, and after passing through the acousto-optic deflector, it passes through the first 4f system composed of the first lens 2 and the second lens 3 to be conjugated with the spatial light modulator 1. After passing through the spatial light modulator 1, it passes through the third lens 5 to reach the focal plane, and is spatially filtered by the pinhole 6. Finally, it passes through the fourth lens 7 to obtain the decoded wavefront distribution.

[0052] The implementation process is as follows:

[0053] 1) After the light beam is deflected by the acousto-optic deflector, it forms the first 4f system through the first lens 2 and the second lens 3, controls the light beam size within the range of the spatial light modulator 1, and conjugates the acousto-optic deflector with the spatial light modulator 1 to ensure the effectiveness of the tilt phase compensation of the acousto-optic deflector. The acousto-optic deflector can be the DTSXY-400 acousto-optic deflector of aa optoelectronic in France.

[0054] 2) The beam phase is controlled by the spatial light modulator 1. The coded wavefront is obtained by matching 9 different zernike aberrations with blazed gratings of different spatial frequencies that are equally spaced in the frequency domain, and summing the complex amplitudes of all the coded wavefronts superimposed with the corresponding blazed gratings and taking the phase part. The coded wavefront is then loaded onto the spatial light modulator 1. Figure 3 As shown, there are 9 zernike aberrations and coded wavefronts. The spatial light modulator can be 1920x1200, 850-1300nm from MeadowlarkOptics of the United States.

[0055] 3) The light beam passing through the spatial light modulator 1 is focused by the third lens 5, and the light intensity distribution at the focal plane is the Fourier transform of the light field at the spatial light modulator 1. Figure 4 The following are the intensity distribution of the coded wavefront and focal plane. The larger the corresponding grating spatial frequency in the coded wavefront, the farther the coded light spot is from the optical axis.

[0056] 4) The pinhole 6 located at the focal plane filters out the coded light spots exceeding a certain spatial frequency, such as Figure 5 As shown, the white circle is the light transmission range of the pinhole 6. The light passing through the pinhole 6 passes through the fourth lens 7 and is inversely Fourier transformed again to obtain the decoded wavefront. Figure 5 As shown, by using an acousto-optic deflector to generate a tilted phase with a spatial frequency opposite to that of the loaded grating, different coded light spots can be deflected to the pinhole 6 to decode different wavefronts. Example 3

[0057] The holographic wavefront shaping system based on Fourier encoding and decoding includes a wavefront encoding component and a wavefront decoding component. The wavefront encoding component is used to perform Fourier encoding on the input light beam to obtain an encoded light beam, and the encoded light beam is incident on the wavefront decoding component; the wavefront decoding component is used to perform Fourier decoding on the incident encoded light beam to obtain a shaped wavefront distribution.

[0058] The wavefront coding component includes a scanning device 4, a first 4f system and a spatial light modulator 1. The scanning device 4 is conjugated with the spatial light modulator 1 through the first 4f system, that is, the spatial light modulator 1 is conjugated with the scanning device 4, wherein the spatial light modulator 1 is used to generate a multiplexed wavefront, the first 4f system is used to adjust the light beam size so that the light beam sizes in the spatial light modulator 1 and the scanning device 4 are the same, and the scanning device 4 is used to generate a tilted phase so that the encoded light beam can selectively decode a specific wavefront after passing through the wavefront decoding component.

[0059] The input light beam is incident into the wavefront decoding component after passing through the scanning device 4, the first 4f system and the spatial light modulator 1. The first 4f system comprises a first lens 2 and a second lens 3 arranged along the optical axis, and the focal points of the first lens 2 and the second lens 3 coincide.

[0060] The wavefront decoding component includes a second 4f system and a pinhole 6, wherein the pinhole 6 is located at the Fourier transform of the second 4f system. At the plane, Only the coded light spot located at the optical axis in the coded light beam is allowed to pass through the pinhole 6, wherein the second 4f system is used to perform Fourier transform and inverse transform on the coded light beam, and the pinhole 6 is used for filtering.

[0061] The second 4f system includes a third lens 5 and a fourth lens 7 arranged along the optical axis, the focal points of the third lens 5 and the fourth lens 7 coincide, a pinhole 6 is placed between the third lens 5 and the fourth lens 7, and the pinhole 6 is coaxially arranged with the third lens 5 and the fourth lens 7, wherein the third lens 5 is used for performing Fourier transform, and the fourth lens 7 is used for performing inverse Fourier transform.

[0062] The spatial light modulator 1 is a phase-type spatial light modulator, and the scanning device 4 is specifically a galvanometer. The light beam is first reflected by the galvanometer, and after passing through the galvanometer, it passes through the first 4f system composed of the first lens 2 and the second lens 3 to be conjugated with the spatial light modulator 1. After passing through the spatial light modulator 1, it passes through the third lens 5 to reach the focal plane, and is spatially filtered by the pinhole 6. Finally, it passes through the fourth lens 7 to obtain the decoded wavefront distribution.

[0063] The implementation process is as follows:

[0064] 1) After the light beam is deflected by the galvanometer, it forms a 4f system through the first lens 2 and the second lens 3, controls the size of the light beam within the range of the spatial light modulator 1, and conjugates the galvanometer with the spatial light modulator 1. The galvanometer can be a 6215h galvanometer from CTI of the United States.

[0065] 2) The beam phase is controlled by the spatial light modulator 1. In the encoding process, multiple different arbitrary wavefronts are matched one by one with Dammann gratings of different spatial frequencies that are equally spaced in the frequency domain, and the complex amplitudes of all the wavefronts to be encoded are superimposed with the corresponding Dammann gratings, and the phase part is taken to obtain the encoded wavefront. The encoded wavefront is loaded onto the spatial light modulator 1. The frequency domain range of the arbitrary wavefront is within the grating frequency domain interval, and the spatial light modulator can be 1920x1200, 850-1300nm from Meadowlark Optics of the United States.

[0066] 3) The light beam passing through the spatial light modulator 1 is focused by the third lens 5, and the light intensity distribution at the focal plane is the Fourier transform of the light beam at the spatial light modulator 1. The larger the corresponding grating spatial frequency in the coded wavefront, the farther the coded light spot is from the optical axis.

[0067] 4) During the decoding process, the pinhole 6 located on the focal plane filters out the coded light spots that exceed the limited spatial frequency of the pinhole 6. The light passing through the pinhole 6 passes through the fourth lens 7 and is inversely Fourier transformed again to obtain the decoded wavefront. By using the galvanometer to generate an inclined phase with a spatial frequency opposite to that of the loaded grating, different coded light spots can be deflected to the pinhole 6 and different wavefronts can be decoded. The size of the pinhole 6 is the maximum frequency domain range of a single multiplexed wavefront, and the galvanometer scanning method is continuous scanning. Example 4

[0068] The holographic wavefront shaping system based on Fourier encoding and decoding includes a wavefront encoding component and a wavefront decoding component. The wavefront encoding component is used to obtain an encoded light beam after Fourier encoding the input light beam. The encoded light beam is incident on the wavefront decoding component. The wavefront decoding component is used to perform Fourier decoding on the incident encoded light beam to obtain a shaped wavefront distribution.

[0069] The wavefront coding component includes a scanning device 4, a first 4f system and a spatial light modulator 1. The scanning device 4 is conjugated with the spatial light modulator 1 through the first 4f system, that is, the spatial light modulator 1 is conjugated with the scanning device 4, wherein the spatial light modulator 1 is used to generate a multiplexed wavefront, the first 4f system is used to adjust the light beam size so that the light beam sizes in the spatial light modulator 1 and the scanning device 4 are the same, and the scanning device 4 is used to generate a tilted phase so that the encoded light beam can selectively decode a specific wavefront after passing through the wavefront decoding component.

[0070] The input light beam is incident into the wavefront decoding component after passing through the scanning device 4, the first 4f system and the spatial light modulator 1. The first 4f system comprises a first lens 2 and a second lens 3 arranged along the optical axis, and the focal points of the first lens 2 and the second lens 3 coincide.

[0071] The wavefront decoding component includes a second 4f system and a pinhole 6, wherein the pinhole 6 is located at the Fourier transform of the second 4f system. At the plane, Only the coded light spot located at the optical axis in the coded light beam is allowed to pass through the pinhole 6, wherein the second 4f system is used to perform Fourier transform and inverse transform on the coded light beam, and the pinhole 6 is used for filtering.

[0072] The second 4f system includes a third lens 5 and a fourth lens 7 arranged along the optical axis, the focal points of the third lens 5 and the fourth lens 7 coincide, a pinhole 6 is placed between the third lens 5 and the fourth lens 7, and the pinhole 6 is coaxially arranged with the third lens 5 and the fourth lens 7, wherein the third lens 5 is used for performing Fourier transform, and the fourth lens 7 is used for performing inverse Fourier transform.

[0073] The spatial light modulator 1 is a phase-type spatial light modulator, and the scanning device 4 is specifically a galvanometer. The light beam is first reflected by the galvanometer, and after passing through the galvanometer, it passes through the first 4f system composed of the first lens 2 and the second lens 3 to be conjugated with the spatial light modulator 1. After passing through the spatial light modulator 1, it passes through the third lens 5 to reach the focal plane, and is spatially filtered by the pinhole 6. Finally, it passes through the fourth lens 7 to obtain the decoded wavefront distribution.

[0074] The implementation process is as follows:

[0075] 1) After the light beam is deflected by the galvanometer, it forms a 4f system through the first lens 2 and the second lens 3, controls the size of the light beam within the range of the spatial light modulator 1, and conjugates the galvanometer with the spatial light modulator 1. The galvanometer can be a 6215h galvanometer from CTI of the United States.

[0076] 2) The beam phase is controlled by the spatial light modulator 1. In the encoding process, multiple different arbitrary wavefronts are generated by calculation of holography, and all the wavefronts to be encoded are distributed at different positions in the frequency domain, thereby obtaining the coded wavefront. The coded wavefront is loaded onto the spatial light modulator 1. The distribution of the coded wavefront in the frequency domain is arbitrary while ensuring no aliasing, and the spatial light modulator can be the 1920x1200, 850-1300nm of Meadowlark Optics in the United States.

[0077] 3) The light beam passing through the spatial light modulator 1 is focused by the third lens 5, and the light intensity distribution at the focal plane is the Fourier transform of the light beam at the spatial light modulator 1. The larger the corresponding grating spatial frequency in the coded wavefront, the farther the coded light spot is from the optical axis.

[0078] 4) During the decoding process, the pinhole 6 located on the focal plane filters out the coded light spots that exceed the spatial frequency limit of the pinhole 6. The light passing through the pinhole 6 passes through the fourth lens 7 and is inversely Fourier transformed again to obtain the decoded wavefront. The galvanometer generates an inclined phase with a spatial frequency opposite to the frequency domain position of the multiplexed wavefront, and different coded light spots can be deflected to the pinhole 6 to decode different wavefronts. The size of the pinhole 6 is the maximum frequency domain range of a single multiplexed wavefront, and the galvanometer scanning method is random scanning.

[0079] In summary, the present invention encodes multiple wavefronts corresponding to gratings with different spatial frequencies; through rapid scanning and pinhole filtering of a scanning device; and finally Fourier transform of the selected coded light spot through a lens; the purpose of decoding a specific wavefront is achieved, thereby realizing rapid complex wavefront switching.

[0080] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0081] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0082] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A holographic wavefront shaping system based on Fourier encoding and decoding, characterized in that: The invention comprises a wavefront encoding component and a wavefront decoding component, wherein the wavefront encoding component is used to perform Fourier encoding on an input light beam and then inject the input light beam into the wavefront decoding component, and the wavefront decoding component is used to perform Fourier decoding on the incident encoded light beam to obtain a shaped wavefront distribution; wherein the wavefront decoding component comprises a second 4f system and a pinhole (6), wherein the pinhole (6) is located at the Fourier position of the second 4f system. At the plane, The coded light beam only allows the coded light spot located at the optical axis to pass through the pinhole (6), wherein the second 4f system is used to perform Fourier transform and inverse transform on the coded light beam, and the pinhole (6) is used for filtering; The wavefront coding component comprises a phase-type spatial light modulator (1), a first 4f system and a scanning device (4); the phase-type spatial light modulator (1) is conjugated with the scanning device (4) through the first 4f system, wherein the coded wavefront is obtained by using a method in which all wavefronts to be coded correspond to gratings of different spatial frequencies; the phase-type spatial light modulator (1) is used to load the coded wavefront of Fourier coding; the first 4f system is used to adjust the light beam size so that the phase-type spatial light modulator (1) and the scanning device (4) are conjugated and the light beam size matches; the scanning device (4) is used to generate a tilted phase so that after the coded light beam passes through the wavefront decoding component, a specific wavefront is selectively decoded.

2. The holographic wavefront shaping system based on Fourier encoding and decoding according to claim 1, characterized in that: The input light beam passes through the phase-type spatial light modulator (1), the first 4f system and the scanning device (4) in sequence and then is incident on the wavefront decoding component, or the input light beam passes through the scanning device (4), the first 4f system and the phase-type spatial light modulator (1) in sequence and then is incident on the wavefront decoding component.

3. The holographic wavefront shaping system based on Fourier encoding and decoding according to claim 1, characterized in that: The scanning device (4) is one of a reflector, a galvanometer, an electro-optical deflector, and an acousto-optical deflector.

4. A holographic wavefront shaping method based on Fourier encoding and decoding, characterized in that: The wavefront shaping method adopts the holographic wavefront shaping system based on Fourier encoding and decoding according to claim 1, and the wavefront shaping method comprises the following steps: 1) The coded wavefront is obtained by using the method that all the wavefronts to be coded correspond to gratings of different spatial frequencies, and the coded wavefront is loaded on the wavefront coding component. When the input light beam passes through the wavefront coding component, a coded light beam is obtained; in the coded light beam, the coded light spots formed by different coded wavefronts are distributed at different spatial positions on the Fourier plane of the second 4f system; 2) During the decoding process, a coded light spot array is formed at the Fourier plane of the second 4f system, and tilt phases of different spatial frequencies are generated by the scanning device (4) in the wavefront coding component. After each tilt phase is superimposed on the corresponding coded wavefront, the corresponding coded light spot in the light spot array is deflected and then passes through the second 4f system and the pinhole (6), finally completing the decoding of the specific wavefront and obtaining the decoded wavefront distribution.

5. The holographic wavefront shaping method based on Fourier encoding and decoding according to claim 4, characterized in that: In the above 1), the grating is one of a blazed grating and a Dammann grating; The distribution of the coded light spot on the Fourier plane of the second 4f system is one of equally spaced distribution, equally spaced distribution along a circle, and adaptive distribution according to the spectrum range of the coded wavefront.

6. The holographic wavefront shaping method based on Fourier encoding and decoding according to claim 4, characterized in that: In the above 1), the method for obtaining the coded wavefront is one of the following methods: summing the complex amplitudes of all the wavefronts to be coded after superposition with the corresponding grating and taking the phase part, or generating a holographic image with a computer.

7. The holographic wavefront shaping method based on Fourier encoding and decoding according to claim 4, characterized in that: In the above 2), the scanning method of the scanning device (4) is one of continuous scanning and random scanning.

8. The holographic wavefront shaping method based on Fourier encoding and decoding according to claim 4, characterized in that: In the above 2), the size of the pinhole (6) is one of the maximum spectrum size of the coded wavefront and the spectrum multiplexing interval.

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