A high-resolution vector-distorted light field generation system based on scattering focusing

Abstract

This invention discloses a high-resolution vector twisted light field generation system based on scattering focusing. It mainly includes a 4f system for generating the twisted vector light field, a microscope objective for focusing and magnifying the target, a scattering medium, and a CMOS receiver. The 4f system includes a spatial light modulator for phase modulation. The system can generate different target twisted vector light fields by adjusting the twisted phase. It can not only quickly calculate the vector optical transmission matrix, but also generate a high-resolution target twisted vector light field behind the scattering medium based on the measured vector transmission matrix. This system is suitable for industries requiring the generation of high-resolution twisted vector light fields behind scattering media, and features convenient operation, flexible control, high light field resolution, and stable performance.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic technology, and more specifically to a high-resolution vector-distorted light field generation system based on scattering focusing. Background Technology

[0002] The traditional optical imaging principle that light travels in a straight line is considered common sense in everyday life, but this applies only in relatively clean environments. The limitation of this principle is that when a light beam propagates in a non-uniformly distributed medium, phase deviations or depolarization effects may occur, rendering this common sense inapplicable.

[0003] When light passes through a scattering medium, its original wavefront phase changes, ultimately resulting in only the observed speckle pattern of the outgoing light. In 2007, Mosk's group utilized wavefront modulation to focus light after it passed through a scattering medium, leading to widespread interest in wavefront phase modulation techniques. It was discovered that an optical transfer matrix can combine the outgoing and incident light passing through the scattering medium, and phase conjugation techniques can enable focusing and imaging at any position and time. In recent years, with continuous research into scattered light, scattering focusing techniques have become increasingly sophisticated. By studying the properties of scattered light, various methods have been employed to achieve applications of focusing imaging through scattering media.

[0004] The twisted phase was first discovered by Simon and Mukunda in 1993. While searching for the most general rotationally invariant coherent optical field, they first discovered this phase, caused by internal asymmetry, that results in the rotation of the light beam during propagation. In 2018, Mei et al. proposed a novel twisted phase, whose concise expression allows for convenient and rapid generation in the laboratory.

[0005] Unfortunately, scattering media often exist in reality, affecting the optical path. In 2012, Tripathi et al. proposed a method for measuring the VTM (Vibration Matrix Transformation). This method can calculate the VTM of the scattering medium and focus the target light field using phase conjugation and a four-step phase shifting method. However, for complex vector light fields, such as the generation of distorted vector light fields through scattering media, there is currently no flexible and stable method available to generate distorted vector light fields behind scattering media, especially high-resolution distorted vector light fields. Exploring such a method is a pressing problem that needs to be solved. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a high-resolution vector-torsional light field generation system based on scattering and focusing. This system enables the generation of different target-torsional vector light fields by controlling the tortuous phase. It not only allows for rapid calculation of the vector optical transfer matrix but also enables the generation of high-resolution target-torsional vector light fields behind the scattering medium based on the measured vector transfer matrix.

[0007] Technical solution

[0008] A high-resolution vector-distorted light field generation system based on scattering focusing includes a laser generator, a 4f system (1), a first microscope objective (3), a scattering medium (4), a second microscope objective (5), a CMOS receiver (6), and a control device arranged sequentially. The 4f system (1) generates a vector light field based on the superposition of two orthogonally circularly polarized beams. The first microscope objective (3) converges the target, and the second microscope objective (5) magnifies the target. The 4f system (1) includes a spatial light modulator (2) that modulates the phase, two Fourier lenses, a dual-aperture filter, and a double cemented carbide filter. The system consists of a waveplate and a Ronchi grating. A dual-aperture filter is used to extract the +1 order beams on the x-axis and y-axis of the spatial light modulator (2) after reflection. The two beams are then passed through a double cemented plate. Different cemented surfaces of the waveplate are converted into left-handed and right-handed circularly polarized light. The left-handed and right-handed circularly polarized light are then collinearly superimposed through a Ronchi grating to generate the target vector beam. The input light field with different polarization and phase distributions depends on the hologram loaded on the spatial light modulator (2). The scattering medium (4) is an isotropic frosted glass with a sand content of 220. The first microscope objective (3) is used to focus the energy of the incident light to penetrate the scattering medium, and the second microscope objective (5) is used to magnify the target and collect the scattered signal after scattering through the scattering medium.

[0009] Furthermore, by loading different holographic phase maps into the spatial light modulator (2) to achieve phase modulation of the input light field, the generated twisted vector light field is represented as follows:

[0010] ,

[0011] Where A0 represents the amplitude. , , and These are the additional phases in the x and y directions, respectively, loaded into the spatial light modulator (2).

[0012] Furthermore, the vector light field obtained by the coherent superposition of two orthogonally circularly polarized beams passing through the scattering medium can be expressed as:

[0013] ,

[0014] Where m, n, p, q represent the input plane (m, n) and the output plane (p, q) points. The vector beam is focused on the scattering medium (4) through the first microscope objective (3), and then collected by the second microscope objective (5) and transmitted to the CMOS receiver (6) as a speckle intensity map. Each column of the Hadamard matrix is ​​used as the input mode. According to the four-step phase shifting method, the elements are calibrated by measuring the corresponding input modes, thereby obtaining all the components of the scattering medium VTM.

[0015] Furthermore, a conjugate operation is performed on the entire VTM, and the resulting modulated wavefront phase is loaded onto the spatial light modulator (2) to overcome the scattering effect. The modulation function of the two-dimensional holographic grating is expressed as:

[0016] ,

[0017] in Indicates spatial carrier frequency, Indicates modulation depth. and The phase distributions carried by the left-handed and right-handed circular polarization bases are respectively represented. The phase distribution of the target's twisted vector light field is then added to the modulation wavefront phase in the spatial light modulator (2), thereby enabling the construction of a twisted vector beam with a spatially varying polarization state through the scattering medium.

[0018] Beneficial effects:

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] It can generate a high-resolution twisted vector light field behind the scattering medium, and its vector focusing effect is nearly 10 times better than that of traditional lens focusing.

[0021] It is highly flexible and suitable for applications requiring high-resolution twisted vector light fields with arbitrary phase or polarization states to be generated behind a scattering medium, and its structure is stable.

[0022] It can generate different target twisted vector light fields by adjusting the twisted phase. It can not only quickly calculate the vector optical transmission matrix, but also generate a high-resolution target twisted vector light field after scattering the medium based on the measured vector transmission matrix. It has the characteristics of convenient operation, flexible control, high light field resolution and stable effect. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the structure of a high-resolution vector twisted light field generation system based on scattering focusing according to the present invention;

[0024] Figure 2A comparison diagram of the twisted beam generated by this system and the high-resolution twisted vector beam generated by this system behind the scattering medium;

[0025] Figure 3 This is a comparison of the focusing effects of a twisted vector beam obtained by focusing through a conventional lens and a high-resolution vector twisted beam generated by this system after passing through a scattering medium.

[0026] Figure label:

[0027] 4f system 1. Spatial light modulator 2. First microscope objective 3. Scattering medium 4. Second microscope objective 5. CMOS receiver 6. Detailed Implementation

[0028] To better illustrate the content of this invention, the following description is provided in conjunction with the accompanying drawings and examples:

[0029] Depend on Figures 1-3 As shown, a high-resolution vector twisted light field generation system based on scattering focusing includes a laser generator, a 4f system (1), a first microscope objective (3), a scattering medium (4), a second microscope objective (5), a CMOS receiver (6), and a control device (such as a computer) arranged in sequence. The 4f system (1) generates a vector light field based on the superposition of two orthogonal circularly polarized beams. The first microscope objective (3) focuses the energy of the incident light to penetrate the scattering medium 4, and the second microscope objective (5) magnifies the target to collect the scattered signal after the scattering medium 4.

[0030] Depend on Figure 1 As shown, under the control of the control device, the 4f system (1) generates a vector light field based on the superposition of two orthogonal circularly polarized beams. The first microscope objective (3) converges the target, and the second microscope objective (5) magnifies the target. The 4f system (1) includes a spatial light modulator (2) that modulates the phase and two Fourier lenses (not shown) integrated together, a dual-aperture filter (not shown), and a double cemented doublet. A waveplate (not shown) and a Ronchi grating (not shown) are used to extract the +1 order beams on the x-axis and y-axis of the spatial light modulator (2) after reflection by a dual-aperture filter, and the two beams are then passed through a double cemented plate. Different cemented surfaces of the waveplate are converted into left-handed and right-handed circularly polarized light. The left-handed and right-handed circularly polarized light are then superimposed collinearly through a Ronchi grating to generate the target vector beam. The input light field with different polarization and phase distributions depends on the hologram loaded on the spatial light modulator (2). The scattering medium (4) is an isotropic frosted glass with a sand content of 220. The first microscope objective (3) is used to focus the energy of the incident light to penetrate the scattering medium, and the second microscope objective (5) is used to magnify the target and collect the scattered signal after scattering through the scattering medium (4).

[0031] Furthermore, by loading different holographic phase maps into the spatial light modulator (2), the phase modulation effect of the input light field is achieved, and the generated distorted vector light field is represented by Equation 1:

[0032] , (Formula 1)

[0033] Where A0 represents the amplitude. u represents the torsion coefficient. Indicates the initial phase. , , and These are the additional phases in the x and y directions, respectively, loaded into the spatial light modulator (2).

[0034] Furthermore, the twisted vector light field is mainly determined by the twist coefficient u, that is, by adjusting the parameter of the twist coefficient, a twisted vector light field with corresponding twist intensity can be obtained.

[0035] Furthermore, the vector light field obtained by the coherent superposition of two orthogonally circularly polarized beams passing through the scattering medium has a VTM as expressed by the following formula 2:

[0036] （公式2）

[0037] Where m, n, p, q represent the input plane (m, n) and the output plane (p, q) respectively. The vector beam is focused on the scattering medium (4) through the first microscope objective (3), and then collected by the second microscope objective (5) and transmitted to the CMOS receiver (6) as a speckle intensity map. Each column of the Hadamard matrix is ​​used as the input mode. According to the four-step phase shifting method, the elements are calibrated by measuring the corresponding input modes, thereby obtaining all the components of the scattering medium VTM.

[0038] Furthermore, a conjugate operation is performed on the entire VTM, and the resulting modulated wavefront phase is loaded onto the spatial light modulator (2) to overcome the scattering effect. The modulation function of the two-dimensional holographic grating is expressed as:

[0039] （公式3）

[0040] in Indicates spatial carrier frequency, Indicates modulation depth. and The phase distributions carried by the left-handed and right-handed circular polarization bases are respectively represented. The phase distribution of the target's twisted vector light field is then added to the modulation wavefront phase in the spatial light modulator (2), thereby enabling the construction of a twisted vector beam with a spatially varying polarization state through the scattering medium.

[0041] Furthermore, by changing the torsion coefficient u, a high-resolution torsion vector light field of the target can be generated behind the scattering medium.

[0042] Furthermore, a high-resolution twisted vector light field is generated behind the scattering medium, and its vector focusing effect is nearly 10 times better than that of traditional lens focusing.

[0043] Specifically, a 532nm laser source can generate a target twisted vector light field through a high-resolution vector twisted light field generation system based on scattering and focusing. It can also calculate the vector optical transmission matrix and then use the vector transmission matrix to generate a high-resolution twisted vector light field in the scattering medium.

[0044] Figure 2 The paper presents a comparison between the twisted beam generated by this system and the high-resolution twisted vector beam produced by this system after passing through a scattering medium.

[0045] Figure 3 The high-resolution distorted vector light field generated by this system behind the scattering medium is described, and its vector focusing effect is nearly 10 times better than that of traditional lens focusing.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the technical solutions of the present invention have been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A high-resolution vector-distorted light field generation system based on scattering and focusing, characterized in that: The system comprises, in sequence, a laser generator, a 4f system (1), a first microscope objective (3), a scattering medium (4), a second microscope objective (5), a CMOS receiver (6), and a control device; wherein, the 4f system (1) generates a vector light field based on the superposition of two orthogonally circularly polarized beams, the first microscope objective (3) converges the target, and the second microscope objective (5) magnifies the target; the 4f system (1) includes a spatial light modulator (2) that modulates the phase, two Fourier lenses, a dual-aperture filter, and a double cemented carbide. The system consists of a waveplate and a Ronchi grating. A dual-aperture filter is used to extract the +1 order beams on the x-axis and y-axis of the spatial light modulator (2) after reflection. The two beams are then passed through a double cemented plate. Different cemented surfaces of the waveplate are converted into left-handed and right-handed circularly polarized light. The left-handed and right-handed circularly polarized light are then superimposed collinearly through a Ronchi grating to generate a target vector beam. The input light field with different polarization and phase distributions depends on the hologram loaded on the spatial light modulator (2).

2. A high-resolution vector-distorted light field generation system based on scattering focusing according to claim 1, characterized in that: The scattering medium (4) is an isotropic frosted glass with a sand content of 220. The first microscope objective (3) is used to focus the energy of the incident light to penetrate the scattering medium (4). The second microscope objective (5) is used to magnify the target and collect the scattering signal after passing through the scattering medium (4).

3. A high-resolution vector-distorted light field generation system based on scattering focusing according to claim 1, characterized in that: The generated twisted vector optical field, generated using phase modulation based on a 4f system (1), is expressed as: ， Where A0 represents the amplitude. , , and These are the additional phases in the x and y directions, respectively, loaded into the spatial light modulator (2).

4. A high-resolution vector-distorted light field generation system based on scattering focusing according to claim 1, characterized in that: The vector light field obtained by the coherent superposition of two orthogonally circularly polarized beams passes through the scattering medium (4), and its vector transfer matrix (VTM) is expressed as: ， Where m, n, p, q represent the input plane (m, n) point and the output plane (p, q) point respectively. The vector beam is focused on the scattering medium (4) through the first microscope objective (3), and then collected by the second microscope objective (5) and transmitted to the CMOS receiver (6) as a speckle intensity map. Each column of the Hadamard matrix is ​​used as the input mode. According to the four-step phase shifting method, the elements are calibrated by measuring the corresponding input modes, thereby obtaining all the components of the vector transfer matrix (VTM) of the scattering medium (4).

5. A high-resolution vector-distorted light field generation system based on scattering focusing according to claim 4, characterized in that: By performing a conjugate operation on the entire vector transfer matrix (VTM), the obtained modulation wavefront phase is loaded onto the spatial light modulator (2) to overcome the scattering effect. The modulation function of the spatial light modulator (2) is expressed as: ， in Indicates spatial carrier frequency, Indicates modulation depth. and The phase distributions carried by the left-handed and right-handed circular polarization bases are respectively represented. The phase distribution of the target's twisted vector light field is then added to the modulation wavefront phase in the spatial light modulator (2), thereby generating a high-resolution twisted vector beam with spatially varying polarization state behind the scattering medium (4).

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