Scattering focusing-based system for generating focal light field transmitted along curve

Abstract

The invention discloses a system for generating a focal light field transmitted along a curve based on scattering focusing, and the system comprises a laser device which is used for transmitting laser and enabling the laser to enter a 4f system; the 4f system is used for superposing two beams of orthogonal circularly polarized light to generate a vector light field, and comprises a spatial light modulator capable of modulating the phase of the light field, a first Fourier lens, a second Fourier lens, a double-hole filter, a doublet # imgabs0 # wave plate and a Ronchi grating; the spatial light modulator, the first Fourier lens, the double-hole filter, the doublet # imgabs 1 # wave plate, the second Fourier lens and the Ronchi grating are arranged in sequence, the double-hole filter is tightly attached to the doublet # imgabs 2 # wave plate, and the distance between the components is the focal length f of the Fourier lens; a focused light field capable of being transmitted in a bending mode can be generated behind a scattering medium, and the transmission mode is different from a linear transmission mode of a traditional scattering focused light field.

Description

Technical Field

[0001] The invention relates to the field of optoelectronic technology, and in particular to a caustic light field generation system based on scattering focusing and transmitted along a curve. Background Art

[0002] Tiny particles in the scattering medium can cause light waves to deviate from their original propagation direction, causing the light field to become disordered and form speckles. In the early days, people believed that scattering was irreversible. In 2007, Mosk's research group used wavefront modulation technology to change the wavefront phase of light after it passed through the scattering medium, enabling it to be focused after the medium. This research attracted widespread attention. In addition, it has been proven that the propagation process of light in complex media can be characterized using a vector transfer matrix (VTM). In just over a decade, the control of scattered light fields based on wavefront shaping technology has developed rapidly and has been widely used in many fields.

[0003] With the development of scattered light field control technology based on wavefront shaping, manipulating the phase of light fields passing through scattering media has attracted more and more interest. Similarly, caustic light fields with special phase distribution have attracted the attention of scholars due to their special focusing characteristics. However, most studies on caustic beams are limited to traditional conditions, and the research on their reconstruction and control behind high-order scattering media is not rich at present.

[0004] In 2012, Tripathi et al. proposed a method for measuring VTM. This method can measure the VTM of scattering media through a four-step phase shift method and focus the target light field through phase conjugation, but the focused light field is usually transmitted in a straight line and has only a short transmission distance. At present, there is no flexible and stable method on the market to reconstruct the caustic light field that is transmitted in any direction behind the scattering medium. Exploring this method is an urgent problem to be solved. Summary of the invention

[0005] In order to overcome the deficiencies in the above-mentioned prior art, the present invention provides a system for generating a caustic light field that is transmitted along a curve based on scattering focusing, so as to realize the calculation of the vector transmission matrix of the vector light field based on orthogonal circularly polarized light, and use the vector transmission matrix to realize the reconstruction of the vector light field after passing through a high-order scattering medium, and can calculate the corresponding vector transmission matrix by extracting different polarization state components in the speckle after the medium, and use the vector transmission matrices of different components to realize simultaneous focusing of multiple points of different polarization states after passing through the scattering medium, and can realize arbitrary regulation of the focusing position.

[0006] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows: a caustic light field generation system based on scattering focusing and transmitted along a curve, comprising:

[0007] A laser, used for emitting laser light and injecting it into the 4f system;

[0008] The 4f system is used to generate a vector light field by superimposing two orthogonal circularly polarized lights, and comprises a spatial light modulator capable of modulating the phase of the light field, a first Fourier lens, a second Fourier lens, a double-aperture filter, a double-cemented Wave plate and a Ronchi grating; the order of arrangement is spatial light modulator, first Fourier lens, double hole filter, double cemented Wave plate, second Fourier lens, Ronchi grating, double hole filter close to double cementation Wave plate, except for the distance between each element is the focal length f of the Fourier lens. After the laser is incident on the spatial light modulator, the +1 order beams on the x-axis and y-axis of the spectrum are extracted through a double-hole filter, and the two beams are respectively passed through a double glue The different glued surfaces of the wave plate are converted into circularly polarized light with orthogonal left-handed and right-handed polarization directions, and finally the two beams are combined into a vector beam through a Ronchi grating;

[0009] High-order scattering media, used to scatter vector light beams;

[0010] A first microscope objective lens and a second microscope objective lens are used to scale the speckle generated behind the high-order scattering medium; the first microscope objective lens is used to converge the energy of the incident light to penetrate the high-order scattering medium, and the second microscope objective lens is used to collect the light signal scattered after penetrating the high-order scattering medium;

[0011] The CMOS receiver is used to receive the optical signal collected by the second microscope objective lens and transmit it to the control device;

[0012] Among them, using phase modulation based on the 4f system, the generated vector light field is shown in the following formula 1:

[0013]

[0014] Where A0 is the amplitude, a represents the caustic coefficient, λ represents the wavelength, r=b1x+b2y represents any direction in the rectangular coordinate system, φ0 represents the initial phase, δ1 and δ2 are the additional phases loaded into the spatial light modulator in the x-direction and y-direction respectively. The caustic light field is mainly determined by the caustic coefficient a and the direction r. That is, by adjusting the caustic coefficient and direction and other parameters, the caustic light field with the corresponding caustic intensity and bending direction can be obtained.

[0015] Furthermore, a vector light field is obtained by coherently superposing two circularly polarized lights orthogonal to the left-handed and right-handed polarization directions and passes through the high-order scattering medium, and its vector transfer matrix (VTM) is shown in the following formula 2:

[0016]

[0017] Where m, n, p, and q represent the input plane (m, n) point and the output plane (p, q) point respectively.

[0018] Furthermore, the vector light beam is focused on the high-order scattering medium through the first microscope objective and then collected by the second microscope objective and transmitted to the CMOS receiver in the form of an intensity speckle pattern. Each column of the Hadamard matrix is ​​used as the input pattern. According to the four-step phase shifting method and by measuring the corresponding input pattern calibration elements, all components of the vector transfer matrix (VTM) of the high-order scattering medium are obtained.

[0019] Furthermore, by performing a conjugate operation on the vector transfer matrix (VTM) as a whole, the modulated wavefront phase is obtained and loaded into the spatial light modulator, thereby overcoming the scattering effect caused by the high-order scattering medium. The modulation function of the spatial light modulator is shown in the following formula 3:

[0020]

[0021] Where γ represents the modulation depth, f0 represents the spatial carrier frequency, and Respectively represent the phase distribution of left-handed and right-handed circularly polarized light. and By adjusting the caustic coefficient a and the direction r, a caustic light field with target caustic and bending directions can be generated.

[0022] Furthermore, the high-order scattering medium is isotropic frosted glass with a grit of 220 or an anisotropic material made of zinc oxide (ZnO) nanoparticles.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] (1) It can generate a caustic light field that can be transmitted in a flexible manner behind a scattering medium. Its transmission mode is different from the linear transmission mode of the traditional scattered focused light field.

[0025] (2) It has high flexibility and can generate a diffuse light field that is transmitted in any direction by adjusting the diffuse coefficient and directional parameters. It can also generate multiple diffuse light fields that are transmitted in different directions at the same time, and the structure is stable.

[0026] (3) It is suitable for fields that need to simultaneously focus the scattered light field transmitted along curves in different directions behind a high-order scattering medium. It has the characteristics of convenient operation, flexible control, and stable effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the structure of the present invention;

[0028] Figure 2 It is a schematic diagram of a scattered focused beam of a vector light field based on orthogonal circularly polarized light;

[0029] Figure 3 It is the caustic light field transmitted along the curve generated by the system after passing through the scattering medium;

[0030] Figure 4 It is a caustic light field that is simultaneously generated by the system after passing through a scattering medium and is transmitted in different directions.

[0031] In the figure: 4f system 1, spatial light modulator 2, first Fourier lens 3, double-hole filter 4, double cementation Wave plate 5 , second Fourier lens 6 , Ronchi grating 7 , first microscope objective 8 , scattering medium 9 , second microscope objective 10 , CMOS receiver 11 . DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] like Figure 1-Figure 4 As shown, the technical solution adopted by the present invention is as follows: This embodiment provides and discloses a caustic light field generation system based on scattering focusing and transmitted along a curve, including a 4f system 1 that generates a vector light field based on orthogonal circularly polarized light under the control of a control device, a laser for emitting laser and incident on the 4f system, a first microscope objective lens 8 for focusing the target, a high-order scattering medium 9, a second microscope objective lens 10 for magnifying the target, a CMOS receiver 11 and a control device (such as Figure 1 computer on the right side of the screen).

[0034] The high-order scattering medium 9 is used to allow the vector light beam to pass through and scatter, and is preferably an isotropic frosted glass with a sand degree of 220 or an anisotropic material made of zinc oxide (ZnO) nanoparticles. The first microscope objective lens 8 and the second microscope objective lens 10 are used to scale the speckle generated after the high-order scattering medium 9; the first microscope objective lens 8 is used to converge the energy of the incident light to penetrate the high-order scattering medium 9, and the second microscope objective lens 10 is used to collect the light signal scattered after penetrating the high-order scattering medium 9; the CMOS receiver 11 is used to receive the light signal collected by the second microscope objective lens 10 and transmit it to the control device;

[0035] Further, such as Figure 1 As shown, the 4f system is used to superimpose two orthogonal circularly polarized light beams to generate a vector light field, including a spatial light modulator 2 capable of modulating the phase of the light field, a first Fourier lens 3, a second Fourier lens 6, a double-aperture filter 4, and a double-cemented Wave plate 5 and a Ronchi grating 7; the order of arrangement is spatial light modulator 2, first Fourier lens 3, double hole filter 4, double glued Wave plate 5, second Fourier lens 6, Ronchi grating 7, double-aperture filter 4 are closely glued together Wave plate 5, except for the distance between each element is the focal length f of the Fourier lens. After the laser is incident on the spatial light modulator 2, the +1 order beams on the x-axis and y-axis of the spectrum are extracted through the double-hole filter 4, and the two beams are respectively made to pass through the double glue The different glued surfaces of the wave plate 5 are converted into circularly polarized light with orthogonal left-handed and right-handed polarization directions, and finally the two beams are combined into a vector beam through the Ronchi grating 7; the input light field with different polarization and phase distribution depends on the hologram loaded on the spatial light modulator.

[0036] Furthermore, using phase modulation based on the 4f system, the generated vector light field is shown in the following formula 1:

[0037]

[0038] Where A0 is the amplitude, a represents the caustic coefficient, λ represents the wavelength, r=b1x+b2y represents any direction in the rectangular coordinate system, φ0 represents the initial phase, δ1 and δ2 are the additional phases loaded into the spatial light modulator 2 in the x direction and the y direction, respectively. The caustic light field is mainly determined by the caustic coefficient a and the direction r. That is, by adjusting the caustic coefficient and direction and other parameters, the caustic light field with the corresponding caustic intensity and bending direction can be obtained.

[0039] Furthermore, the vector light field obtained by coherently superposing the two circularly polarized lights in the orthogonal left-handed and right-handed polarization directions passes through the high-order scattering medium 9, and its vector transfer matrix (VTM) is shown in the following formula 2:

[0040]

[0041] Where m, n, p, and q represent the input plane (m, n) point and the output plane (p, q) point respectively.

[0042] Furthermore, the vector light beam is focused on the high-order scattering medium 9 through the first microscope objective 8, and then collected by the second microscope objective 10 and transmitted to the CMOS receiver 11 in the form of an intensity speckle pattern. Each column of the Hadamard matrix is ​​used as an input pattern, and the elements are calibrated according to the four-step phase shifting method and by measuring the corresponding input pattern, so as to obtain all components of the vector transfer matrix (VTM) of the high-order scattering medium 9.

[0043] Furthermore, by performing a conjugate operation on the vector transfer matrix (VTM) as a whole, the modulated wavefront phase is obtained and loaded into the spatial light modulator 2, thereby overcoming the scattering effect caused by the high-order scattering medium 9. The modulation function of the spatial light modulator 2 is shown in the following formula 3:

[0044]

[0045] Where γ represents the modulation depth, f0 represents the spatial carrier frequency, and Respectively represent the phase distribution of left-handed and right-handed circularly polarized light. and By adjusting and controlling, a caustic light field transmitted along a curve can be generated behind the scattering medium 9. By changing the caustic coefficient a and the direction r, a caustic light field with a target caustic and bending direction can be generated.

[0046] It should be added that Figure 3 The dotted line in FIG. 1 is a comparison line, which is a transmission trajectory when no caustic phase is added (ie, a normal focused light field). The comparison line is used as a reference line to prove that the transmission trajectory of the caustic light field is a curve.

[0047] Specifically, the light source is a laser source with a wavelength of 532nm. A caustic light field generation system based on scattering focusing and transmitted along a curve can realize the generation of a target caustic light field, and can realize the measurement of a vector optical transmission matrix, and then use its vector transmission matrix to generate a caustic light field transmitted along a curve in any direction behind the scattering medium 9;

[0048] Figure 2The scattered focused beams of vector light fields based on orthogonal circularly polarized light generated by this system are described;

[0049] Figure 3 It is explained that this system can generate a caustic light field that propagates along a curve behind a scattering medium;

[0050] Figure 4 It is explained that this system can simultaneously generate multiple caustic light fields that are bent and transmitted in different directions behind the scattering medium.

[0051] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A caustic light field generation system based on scattering focusing and transmitted along a curve, characterized in that: include: A laser, used for emitting laser light and injecting it into the 4f system (1); The 4f system (1) is used to generate a vector light field by superimposing two orthogonal circularly polarized light beams, and comprises a spatial light modulator (2) capable of modulating the phase of the light field, a first Fourier lens (3), a second Fourier lens (6), a double-aperture filter (4), and a double-cemented wave plate (5) and a Ronchi grating (7); the sequence of arrangement is spatial light modulator (2), first Fourier lens (3), double hole filter (4), double glued Wave plate (5), second Fourier lens (6), Ronchi grating (7), double-aperture filter (4) are glued together closely. Wave plate (5), the distance between all other components is the focal length f of the Fourier lens. After the laser is incident on the spatial light modulator (2), the +1 order beams on the x-axis and y-axis of the spectrum are extracted through the double-hole filter (4), and the two beams are respectively made to pass through the double glue The different glued surfaces of the wave plate (5) are converted into circularly polarized light with orthogonal left-handed and right-handed polarization directions, and finally the two beams are combined into a vector light beam through a Ronchi grating (7); A high-order scattering medium (9) for causing the vector light beam to pass through and be scattered; The first microscope objective lens (8) and the second microscope objective lens (10) are used to scale the speckle generated behind the high-order scattering medium (9); the first microscope objective lens (8) is used to converge the energy of the incident light so as to penetrate the high-order scattering medium (9), and the second microscope objective lens (10) is used to collect the light signal scattered after penetrating the high-order scattering medium (9); The CMOS receiver (11) is used to receive the optical signal collected by the second microscope objective lens (10) and transmit it to the control device; Among them, using phase modulation based on the 4f system, the generated vector light field is shown in the following formula 1: Where A0 is the amplitude, a represents the caustic coefficient, λ represents the wavelength, r=b1x+b2y represents any direction in the rectangular coordinate system, φ0 represents the initial phase, δ1 and δ2 are the additional phases in the x-direction and y-direction respectively loaded into the spatial light modulator (2). The caustic light field is mainly determined by the caustic coefficient a and the direction r, that is, by adjusting the caustic coefficient and the direction and other parameters, the caustic light field with the corresponding caustic intensity and bending direction can be obtained.

2. The caustic light field generation system based on scattering focusing and transmitted along a curve according to claim 1, characterized in that: A vector light field is obtained by coherently superposing two circularly polarized lights with orthogonal left-handed and right-handed polarization directions and passes through the high-order scattering medium (9), and its vector transfer matrix (VTM) is shown in the following formula 2: Where m, n, p, and q represent the input plane (m, n) point and the output plane (p, q) point respectively.

3. The caustic light field generation system based on scattering focusing and transmitted along a curve according to claim 2, characterized in that: The vector light beam is focused on the high-order scattering medium (9) through the first microscope objective (8), and then collected by the second microscope objective (10) and transmitted to the CMOS receiver (11) in the form of an intensity speckle pattern. Each column of the Hadamard matrix is ​​used as an input pattern. According to the four-step phase shifting method and by measuring the corresponding input pattern calibration elements, all components of the vector transfer matrix (VTM) of the high-order scattering medium (9) are obtained.

4. The caustic light field generation system based on scattering focusing and transmitted along a curve according to claim 3, characterized in that: By performing a conjugate operation on the vector transfer matrix (VTM) as a whole, the modulated wavefront phase is obtained and loaded into the spatial light modulator (2), thereby overcoming the scattering effect caused by the high-order scattering medium (9). The modulation function of the spatial light modulator (2) is shown in the following formula 3: Where γ represents the modulation depth, f0 represents the spatial carrier frequency, and Respectively represent the phase distribution of left-handed and right-handed circularly polarized light. and By adjusting and controlling, a caustic light field transmitted along a curve can be generated behind the scattering medium (9). By changing the caustic coefficient a and the direction r, a caustic light field with a target caustic and bending direction can be generated.

5. The caustic light field generation system based on scattering focusing and transmitted along a curve according to claim 1, characterized in that: The high-order scattering medium (9) is isotropic ground glass with a sandiness of 220 or an anisotropic material made of zinc oxide (ZnO) nanoparticles.

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