Transmission invariant structured light field generation system and method

Abstract

The invention provides a transmission invariant structured light field generation system and method. Relates to the technical field of light transmission, and solves the problem that a light field with an invariable structure cannot be transmitted at will, and the method comprises the steps: transmitting a laser beam through an input light field generation assembly, carrying out the spatial filtering and beam expansion of the laser beam, converting the laser beam into a fundamental mode Gaussian beam, and transmitting the fundamental mode Gaussian beam to a light field modulation assembly; through the light field modulation assembly, loading a dynamic phase hologram obtained by combining transmission invariant structure light field Fourier spectrums at different positions with corresponding propagation phases for coding to the fundamental mode Gaussian beam; the loaded light beam is transmitted to the output light field acquisition assembly; and carrying out inverse Fourier transform on the loaded light beam through an output light field acquisition assembly, and capturing light spots of the light beam subjected to the inverse Fourier transform at a plurality of preset positions. According to the invention, the generation of the light field with the invariant transmission structure is realized, and the practicability is high.

Description

Technical Field

[0001] The present invention relates to the field of optical transmission technology, and in particular to a transmission invariant structure light field generation system and method. Background Art

[0002] Transmission-invariant structured light field, also known as non-diffraction beam, refers to a beam whose wavefront or cross-sectional light intensity distribution remains unchanged during the spatial transmission of the light field. Compared with the traditional Gaussian laser mode, this beam can be transmitted over long distances with very little energy loss. It has a wide range of applications in optical communications, optical imaging, particle manipulation, etc. In the past decade or so, a large number of exciting studies have emerged on typical non-diffraction beams, such as Bessel beams and Airy beams. On the one hand, Bessel beams are the exact solution of the transmission-invariant mode of the Helmholtz equation and are the most typical type of non-diffraction beams. Their main lobe does not broaden significantly during long-distance transmission, showing non-diffraction characteristics. On the other hand, Airy beams are a special solution of the Schrödinger equation under paraxial conditions. This solution has the characteristics of non-diffraction, self-acceleration and self-healing, so Airy beams also show the characteristics of non-diffraction and self-healing. However, the non-diffraction propagation of such beams over sufficiently long distances usually requires the beam to carry infinite energy, and when propagating over short distances, the beam sidelobes will also have an adverse effect on related applications. In recent years, another type of non-diffraction beam has emerged. In 2019, APL Photonics, Vol. 4, No. 7, p. 7, published "Robust propagation of pin-like optical beam through atmospheric turbulence", proposed a needle-shaped beam that has a stable wavefront during long-distance propagation in free space and can resist diffraction and environmental turbulence. In 2021, Photonics Research, Vol. 9, No. 7, pp. 1204-1212, published "Free-space realization of tunable pin-like optical vortex beams", proposed a needle-shaped vortex beam. This beam carrying angular momentum has an adjustable peak intensity and strong anti-diffraction propagation, which is achieved by modulating the amplitude and phase distribution of a standard laser beam. However, these two types of beams can only generate specific transmission-invariant structured light fields, and cannot generate arbitrary transmission-invariant structured light fields. Nonlinear optical solitons can also generate non-diffraction beams, but they require ideal nonlinear media and are not suitable for practical free-space applications. Therefore, the realization of arbitrary transmission-invariant structured light fields is an urgent problem to be solved in practical applications. Summary of the invention

[0003] A brief overview of the present invention is provided below in order to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to identify key or important parts of the present invention, nor is it intended to limit the scope of the present invention. Its purpose is merely to present certain concepts in a simplified form as a prelude to a more detailed description discussed later.

[0004] In view of this, the present invention provides a transmission invariant structured light field generation system and method, so as to at least solve the problem in the prior art that an arbitrary transmission invariant structured light field cannot be realized.

[0005] According to one aspect of the present invention, there is provided a transmission invariant structure light field generation system, comprising: an input light field generation component, a light field modulation component, and an output light field acquisition component;

[0006] The input light field generating component is configured to emit a laser beam, spatially filter and expand the laser beam, convert it into a fundamental mode Gaussian beam, and transmit the fundamental mode Gaussian beam to the light field modulating component;

[0007] The light field modulation component loads the dynamic phase hologram obtained by combining the Fourier spectrum of the transmission invariant structure light field at different positions with the corresponding propagation phase to the fundamental mode Gaussian beam; and transmits the loaded beam to the output light field acquisition component;

[0008] The output light field acquisition component is configured to perform inverse Fourier transform on the loaded light beam and capture the light spots of the inverse Fourier transformed light beam at multiple preset positions.

[0009] In a preferred embodiment of the present invention, the input light field generating component comprises: a laser and a spatial filtering component, and the spatial filtering component comprises: a first spatial filtering lens, an aperture, and a second spatial filtering lens;

[0010] The first spatial filter lens and the second spatial filter lens are coaxially arranged to form a 4f beam expansion system. The aperture is set at the common focus between the first spatial filter lens and the second spatial filter lens. The laser beam generated by the laser is converged to the aperture through the first spatial filter lens, and is transmitted to the second spatial filter lens through the aperture to expand the beam, forming a fundamental mode Gaussian beam.

[0011] In a preferred embodiment of the present invention, the system further comprises: a polarization splitting component;

[0012] The polarization beam splitting component performs polarization state conversion and intensity control on the fundamental mode Gaussian light beam to form a fundamental mode Gaussian light beam with a horizontal polarization state, and transmits the fundamental mode Gaussian light beam to the light field modulation component.

[0013] In a preferred embodiment of the present invention, the polarization splitting component includes: a half-wave plate and a polarization splitter, the fundamental mode Gaussian beam is converted into a fundamental mode Gaussian beam in a horizontal polarization state through the half-wave plate and the polarization splitter, and the angle of the half-wave plate is adjusted so that the intensity of the fundamental mode Gaussian beam with a horizontal polarization state emitted through the polarization splitter meets a preset condition.

[0014] In a preferred embodiment of the present invention, the light field modulation component includes: a liquid crystal spatial light modulator or a digital micromirror.

[0015] In a preferred embodiment of the present invention, the output light field acquisition component includes: a Fourier transform lens and a CCD camera, the loaded light beam is subjected to inverse Fourier transform through the Fourier transform lens, and the light spot of the inverse Fourier transformed light beam is captured by the CCD camera at multiple preset positions.

[0016] In a second aspect, the present invention further provides a method for generating a transmission invariant structured light field, comprising:

[0017] A laser beam is emitted through an input light field generation component, and the laser beam is spatially filtered and expanded to be converted into a fundamental mode Gaussian beam, and the fundamental mode Gaussian beam is transmitted to a light field modulation component;

[0018] Through the light field modulation component, the dynamic phase hologram obtained by combining the Fourier spectrum of the transmission invariant structure light field at different positions with the corresponding propagation phase for encoding is loaded onto the fundamental mode Gaussian beam; and the loaded beam is transmitted to the output light field acquisition component;

[0019] The loaded light beam is subjected to inverse Fourier transformation through the output light field acquisition component, and the light spot of the light beam subjected to inverse Fourier transformation is captured at a plurality of preset positions.

[0020] In a preferred embodiment of the present invention, before transmitting the fundamental mode Gaussian beam to the light field modulation component, the method further includes:

[0021] The fundamental mode Gaussian light beam is subjected to polarization state conversion and intensity control through a polarization beam splitting component to form a fundamental mode Gaussian light beam with a horizontal polarization state, and is transmitted to the light field modulation component.

[0022] In a preferred embodiment of the present invention, the dynamic phase hologram obtained by encoding the Fourier spectrum of the transmission invariant structure light field at different positions with the corresponding propagation phase is loaded onto the fundamental mode Gaussian beam, which includes:

[0023] The Fourier spectrum of the transmission invariant structure light field at different positions is combined with the spatial propagation phase to generate a dynamic phase hologram, and the dynamic phase hologram is used to perform complex amplitude modulation on a fundamental mode Gaussian light beam with a horizontal polarization state.

[0024] In a preferred embodiment of the present invention, the dynamic phase hologram obtained by encoding the Fourier spectrum of the transmission invariant structure light field at different positions with the corresponding propagation phase is loaded onto the fundamental mode Gaussian beam, which includes:

[0025] Changing the distance between the transmission invariant structure light field and the virtual Fourier transform lens by digital control, and generating phase holograms corresponding to different positions of the transmission invariant structure light field relative to the virtual Fourier transform lens by coding calculation based on a complex amplitude modulation method;

[0026] The corresponding phase hologram of each position is loaded onto the fundamental mode Gaussian beam with a horizontal polarization state.

[0027] The present invention realizes digital control of transmission-invariant structured light fields through the relationship between the distance at which the incident light field in the 4f system is transmitted invariantly in space and the focal length of the lens. Based on the characteristics of the 4f system and the angular spectrum theory, the hologram of the continuously changing structured light field is loaded onto the spatial light modulation device, thereby realizing the generation of arbitrary transmission-invariant structured light fields, which has strong practicality. Compared with optical needle beams and free-space needle-shaped vortex beams, the system and method provided by the present invention have the advantage of realizing the transmission of arbitrary structured light fields invariantly in space. In addition, compared with optical solitons, the system and method provided by the present invention do not require ideal nonlinear media and are suitable for practical free-space applications. Compared with linear non-diffraction light beams (such as Bessel beams, Airy beams, etc.), the system and method provided by the present invention do not need to carry infinite energy to achieve non-diffraction propagation. It has a wide range of applications in optical scanning, optical imaging, particle manipulation, etc.

[0028] These and other advantages of the present invention will become more apparent through the following detailed description of the best embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention may be better understood by referring to the following description given in conjunction with the accompanying drawings, wherein the same or similar reference numerals are used throughout the drawings to represent the same or similar components. The accompanying drawings, together with the following detailed description, are included in and form a part of this specification and are used to further illustrate the preferred embodiments of the present invention and to explain the principles and advantages of the present invention. In the drawings:

[0030] Figure 1 is a structural schematic diagram showing a transmission invariant structure light field generating system of the present invention;

[0031] Figure 2 is an exemplary schematic diagram showing the principle of the method for generating a transmission invariant structured light field of the present invention;

[0032] Figure 3 is a schematic diagram showing the spot of the transmission-invariant super-Gaussian beam of the present invention;

[0033] Figure 4 is a schematic diagram showing the light spot of the transmission-invariant perfect vortex beam of the present invention;

[0034] Figure 5 is a schematic diagram showing the light spot of the transmission-invariant superimposed circular Airy beam of the present invention;

[0035] Among them, 1 represents a laser, 2 represents a first spatial filter lens, 3 represents an aperture, 4 represents a second spatial filter lens, 5 represents a half-wave plate, 6 represents a polarization beam splitter, 7 represents a light field modulation component, 8 represents a Fourier transform lens, and 9 represents a CCD camera;

[0036] Figure 3 (a) is a schematic diagram of the light field distribution of the transmitted invariant super-Gaussian beam;

[0037] Figure 3 (b) Figure 3 (a) Spot image at the dotted line position;

[0038] Figure 3 (c) Figure 3 (b) Light intensity distribution curve at the dotted line position;

[0039] Figure 4 (a) Schematic diagram of the light field distribution of the transmitted invariant perfect vortex beam;

[0040] Figure 4 (b) Figure 4 (a) Spot image at the dotted line position;

[0041] Figure 4 (c) Figure 4 (b) Light intensity distribution curve at the dotted line position;

[0042] Figure 5 (a) Schematic diagram of the light field distribution of the transmission-invariant superposition circular Airy beam;

[0043] Figure 5 (b) Figure 5 (a) Spot image at the dotted line position.

[0044] Those skilled in the art will appreciate that the elements in the drawings are shown only for simplicity and clarity and are not necessarily drawn to scale. For example, the size of some elements in the drawings may be enlarged relative to other elements to help improve the understanding of the embodiments of the present invention. DETAILED DESCRIPTION

[0045] Exemplary embodiments of the present invention will be described below in conjunction with the accompanying drawings. For the sake of clarity and conciseness, not all features of actual implementations are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the process of developing any such actual implementation in order to achieve the developer's specific goals, such as meeting those constraints related to the system and business, and these constraints may vary from implementation to implementation. In addition, it should be understood that although the development work may be very complex and time-consuming, it is only a routine task for those skilled in the art who benefit from the present disclosure.

[0046] It is also necessary to explain here that, in order to avoid obscuring the present invention due to unnecessary details, only the device structure and / or processing steps closely related to the scheme according to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0047] like Figure 1 As shown, an embodiment of the present invention provides a transmission invariant structure light field generation system, including: an input light field generation component, a light field modulation component, and an output light field acquisition component;

[0048] The input light field generating component is configured to emit a laser beam, spatially filter and expand the laser beam, convert it into a fundamental mode Gaussian beam, and transmit the fundamental mode Gaussian beam to the light field modulating component;

[0049] The light field modulation component loads the dynamic phase hologram obtained by combining the Fourier spectrum of the transmission invariant structure light field at different positions with the corresponding propagation phase to the fundamental mode Gaussian beam; and transmits the loaded beam to the output light field acquisition component;

[0050] The output light field acquisition component is configured to perform inverse Fourier transform on the loaded light beam and capture the light spots of the inverse Fourier transformed light beam at multiple preset positions.

[0051] In a preferred embodiment of the present invention, the input light field generating component comprises: a laser 1 and a spatial filtering component, and the spatial filtering component comprises: a first spatial filtering lens 2, an aperture 3 and a second spatial filtering lens 4;

[0052] The first spatial filter lens 2 and the second spatial filter lens 4 are coaxially arranged to form a 4f beam expansion system. The aperture 3 is set at the common focus between the first spatial filter lens 2 and the second spatial filter lens 4. The laser beam generated by the laser 1 is converged to the aperture 3 through the first spatial filter lens 2, and is transmitted to the second spatial filter lens 4 through the aperture 3 for beam expansion to form a fundamental mode Gaussian beam.

[0053] The aperture 3 in the embodiment of the present invention may be a pinhole, and the first spatial filter lens 2 and the second spatial filter lens 4 form a coaxially arranged beam expansion system, wherein the focal length of the first spatial filter lens 2 is smaller than the focal length of the second spatial filter lens 4, and the aperture 3 is at the common focus of the two spatial filter lenses.

[0054] In a preferred embodiment of the present invention, the system further comprises: a polarization splitting component;

[0055] The polarization beam splitting component converts the polarization state and controls the intensity of the fundamental mode Gaussian light beam to form a fundamental mode Gaussian light beam with a horizontal polarization state, and transmits it to the light field modulation component 7.

[0056] In a preferred embodiment of the present invention, the polarization splitting component includes: a half-wave plate 5 and a polarization splitter 6, and the half-wave plate 5 and the polarization splitter 6 are arranged along the optical path on the rear side of the second spatial filter lens 4, and the fundamental mode Gaussian beam is converted into a fundamental mode Gaussian beam in a horizontal polarization state through the half-wave plate 5 and the polarization splitter 6, and the angle of the half-wave plate 5 is adjusted so that the intensity of the fundamental mode Gaussian beam with a horizontal polarization state emitted through the polarization splitter 6 meets a preset condition.

[0057] In the embodiment of the present invention, the polarization beam splitter 6 is fixedly arranged behind the second spatial filter lens 4, and the intensity of the fundamental mode Gaussian beam with a horizontal polarization state is controlled by rotating the half-wave plate 5 so that the emitted intensity meets the preset conditions.

[0058] In a preferred embodiment of the present invention, the light field modulation component 7 includes: a liquid crystal spatial light modulator or a digital micromirror.

[0059] In a preferred embodiment of the present invention, the output light field acquisition component includes: a Fourier transform lens 8 and a CCD camera 9. The loaded light beam is subjected to inverse Fourier transform through the Fourier transform lens 8, and the light spot of the inverse Fourier transformed light beam is captured by the CCD camera 9 at multiple preset positions.

[0060] In the embodiment of the present invention, the Fourier transform lens 8 may be a convex lens with a focal length of 200 mm.

[0061] In the embodiment of the present invention, the laser light emitted by the laser 1 is converted into a Gaussian TEM signal by a spatial filter assembly composed of a first spatial filter lens 2, an aperture 3 and a second spatial filter lens 4. 00 mode. In order to control the polarization state and intensity of the output beam, a half-wave plate 5 and a polarization beam splitter 6 are introduced. Next, the transmission TEM with horizontal polarization 00 The pattern light beam is irradiated to the light field modulation component 7 (the light field modulation component includes a spatial light modulation device, such as a liquid crystal-spatial light modulator or a digital micromirror, etc.). The encoded dynamic phase hologram is loaded on the spatial light modulation device, and the Fourier spectrum of the structured light field at different positions is combined with the corresponding propagation phase. In this way, the phase hologram can be encoded based on complex amplitude modulation to form a dynamic hologram. Afterwards, a Fourier transform lens 8 with a focal length of 200 mm is used to perform an inverse Fourier transform, and the light spots at different positions are captured by moving the CCD camera 9.

[0062] In a second aspect, the present invention further provides a method for generating a transmission invariant structured light field, comprising:

[0063] A laser beam is emitted through an input light field generation component, and the laser beam is spatially filtered and expanded to be converted into a fundamental mode Gaussian beam, and the fundamental mode Gaussian beam is transmitted to a light field modulation component;

[0064] Through the light field modulation component, the dynamic phase hologram obtained by combining the Fourier spectrum of the transmission invariant structure light field at different positions with the corresponding propagation phase for encoding is loaded onto the fundamental mode Gaussian beam; and the loaded beam is transmitted to the output light field acquisition component;

[0065] The loaded light beam is subjected to inverse Fourier transformation through the output light field acquisition component, and the light spot of the light beam subjected to inverse Fourier transformation is captured at a plurality of preset positions.

[0066] In a preferred embodiment of the present invention, before transmitting the fundamental mode Gaussian beam to the light field modulation component, the method further includes:

[0067] The fundamental mode Gaussian light beam is subjected to polarization state conversion and intensity control through a polarization beam splitting component to form a fundamental mode Gaussian light beam with a horizontal polarization state, and is transmitted to the light field modulation component.

[0068] In a preferred embodiment of the present invention, the dynamic phase hologram obtained by encoding the Fourier spectrum of the transmission invariant structure light field at different positions with the corresponding propagation phase is loaded onto the fundamental mode Gaussian beam, which includes:

[0069] The Fourier spectrum of the transmission invariant structure light field at different positions is combined with the spatial propagation phase to generate a dynamic phase hologram, and the dynamic phase hologram is used to perform complex amplitude modulation on a fundamental mode Gaussian light beam with a horizontal polarization state.

[0070] In a preferred embodiment of the present invention, the dynamic phase hologram obtained by encoding the Fourier spectrum of the transmission invariant structure light field at different positions with the corresponding propagation phase is loaded onto the fundamental mode Gaussian beam, which includes:

[0071] Changing the distance between the transmission invariant structure light field and the virtual Fourier transform lens by digital control, and generating phase holograms corresponding to different positions of the transmission invariant structure light field relative to the virtual Fourier transform lens by coding calculation based on a complex amplitude modulation method;

[0072] The corresponding phase hologram of each position is loaded onto the fundamental mode Gaussian beam with a horizontal polarization state.

[0073] In the embodiment of the present invention, a phase hologram of a transmission invariant structured light field is generated by digital control. In the light field modulation component, there is no physical Fourier transform lens in the optical path. Instead, it is added to the process of generating the phase hologram in the form of a virtual Fourier transform lens in the form of code.

[0074] The principle of generating a transmission-invariant structured light field in the example of the present invention is as follows: first, the incident light field is placed on the object plane of a 4f system composed of two Fourier transform lenses. Then, the incident light field moves toward the first Fourier transform lens. The distance over which the incident light field is transmitted unchanged after the second Fourier transform lens is related to the moving distance of the incident light field and the focal lengths of the two Fourier transform lenses. The incident light field is regulated to move a small distance toward the first Fourier transform lens and gradually reaches the front surface of the first Fourier transform lens. This process can achieve diffraction-free propagation of the incident light field within a certain distance to obtain a transmission-invariant light field.

[0075] Specifically, Figure 2 It is known that the distance from the incident light field U1(x1,y1) to the first lens is d0, the focal length of the first Fourier transform lens is f1, the focal length of the second Fourier transform lens is f2, and the position where the outgoing light field and the incident light field remain unchanged is z.

[0076] U2(f x ,f y ) is the frequency domain expression of the light field U2(x2,y2) from U1(x1,y1) passing through the first Fourier transform lens to the back focal plane.

[0077]

[0078] in, is the spatial frequency in the x and y directions, i is the imaginary unit, and λ is the wavelength corresponding to the incident light field U1(x1,y1).

[0079] U2(x2,y2) propagates through the second Fourier transform lens to its rear focal plane, which is equivalent to an inverse Fourier transform. The expression is as follows:

[0080]

[0081] U3(x3,y3) is the expression of the light field emitted from the focal plane behind the second lens, and then propagates through space to the light field at a distance z:

[0082]

[0083] in, k is the wave number.

[0084] According to the expression of U3(x3,y3), we get:

[0085]

[0086] therefore,

[0087]

[0088] when (Right now )hour:

[0089]

[0090] Perform inverse Fourier transform on both sides of the above equation, that is:

[0091]

[0092] The intensity distribution at position z is:

[0093] I z (x z ,y z )∝I1(x1,y1).

[0094] Therefore, when Specifically, the incident light field on the front focal plane of the first Fourier transform lens moves toward the first Fourier transform lens. By adjusting the distance d0 between the incident light field and the first Fourier transform lens, that is, adjusting f1-d0 to increase from 0 to f1 in a small distance, this process can achieve the incident light field at f2 2 / f1 distance to obtain a diffraction-free light field.

[0095] In an embodiment of the present invention, digital control is performed through a light field modulation component, and the first Fourier transform lens of the two Fourier transform lenses that constitute the 4f system generates a hologram through coding calculation based on complex amplitude modulation. A dynamic hologram is obtained by digitally controlling the distance between the incident light field and the first Fourier transform lens, thereby generating a transmission invariant structured light field.

[0096] Example

[0097] A 532nm laser light source is used, and the focal lengths of the two Fourier transform lenses that make up the 4f system are both 200mm. A hologram is generated through coding calculation based on complex amplitude modulation. By digitally controlling the distance between the incident light field and the first Fourier transform lens, a dynamic hologram is obtained, thereby generating a transmission-invariant structured light field. In this embodiment, several transmission-changing structured light fields are selected as target light fields. Among them, the super-Gaussian beam has an obvious self-focusing tendency as the propagation distance increases, and it is impossible to maintain the flat-top beam transmission unchanged. The perfect vortex beam is the Fourier transform of the Bessel beam, and gradually transforms into a Bessel beam during the propagation process, and it is impossible to maintain the perfect vortex beam transmission unchanged. The superimposed circular Airy beam is evolved into a variety of annular lattices during the propagation process and cannot maintain its original state. This type of light field can only be used at a certain plane. Once it propagates, it evolves into other light fields and cannot be used. The system and method of the present invention can obtain a transmission-invariant light field within a certain propagation distance. The experimental results are as follows. Figure 3 to Figure 5 shown. Figure 3 These are the experimental results showing that a super-Gaussian beam of order N=12 remains unchanged during its spatial transmission of 500 mm. Figure 4 This is the experimental result that a perfect vortex beam with a topological charge of 5 remains unchanged during its spatial transmission of 500 mm. Figure 5 This is the experimental result of the structured light field of 50 mm in space after the superposition of circular Airy beams with topological charges of 2 and 12. The structured light field remains unchanged during the 50 mm transmission in space. In order to show its transmission invariance, the light field is extracted at Figure 3 (a) Figure 4 (a) and Figure 5 (a) The spot image at the dotted line position is obtained Figure 3 (b) Figure 4 (b) and Figure 5 (b), Extraction Figure 3 (b) and Figure 4 (b) The light intensity distribution corresponding to the dotted line position is obtained Figure 3 (c) and Figure 4 (c) Light intensity distribution curve. This embodiment verifies that digitally controlled transmission-invariant structured light fields can achieve spatial transmission invariance of various structured light fields.

[0098] Although the present invention has been described according to a limited number of embodiments, it will be apparent to those skilled in the art, with the benefit of the above description, that other embodiments may be envisioned within the scope of the invention thus described. In addition, it should be noted that the language used in this specification is selected primarily for readability and teaching purposes, rather than for explaining or defining the subject matter of the present invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the present invention is illustrative, not restrictive, with respect to the scope of the present invention, which is defined by the appended claims.

Claims

1. A transmission invariant structured light field generation system, characterized in that: include: Input light field generation component, light field modulation component, output light field acquisition component; The input light field generating component is configured to emit a laser beam, spatially filter and expand the laser beam, convert it into a fundamental mode Gaussian beam, and transmit the fundamental mode Gaussian beam to the light field modulating component; The light field modulation component loads the dynamic phase hologram obtained by combining the Fourier spectrum of the transmission invariant structure light field at different positions with the corresponding propagation phase to the fundamental mode Gaussian beam; and transmits the loaded beam to the output light field acquisition component; The output light field acquisition component is configured to perform inverse Fourier transform on the loaded light beam and capture the light spots of the inverse Fourier transformed light beam at multiple preset positions.

2. The system according to claim 1, characterized in that The input light field generating component comprises: a laser and a spatial filtering component, and the spatial filtering component comprises: a first spatial filtering lens, an aperture, and a second spatial filtering lens; The first spatial filter lens and the second spatial filter lens are coaxially arranged to form a 4f beam expansion system. The aperture is set at the common focus between the first spatial filter lens and the second spatial filter lens. The laser beam generated by the laser is converged to the aperture through the first spatial filter lens, and is transmitted to the second spatial filter lens through the aperture to expand the beam, forming a fundamental mode Gaussian beam.

3. The system according to claim 2, characterized in that Also includes: Polarization beam splitting components; The polarization beam splitting component performs polarization state conversion and intensity control on the fundamental mode Gaussian light beam to form a fundamental mode Gaussian light beam with a horizontal polarization state, and transmits the fundamental mode Gaussian light beam to the light field modulation component.

4. The system according to claim 3, characterized in that The polarization splitting component includes: a half-wave plate and a polarization splitter, the fundamental mode Gaussian beam is converted into a fundamental mode Gaussian beam in a horizontal polarization state through the half-wave plate and the polarization splitter, and the angle of the half-wave plate is adjusted so that the intensity of the fundamental mode Gaussian beam in a horizontal polarization state emitted through the polarization splitter meets a preset condition.

5. The system according to claim 1, characterized in that The light field modulation component includes: a liquid crystal-spatial light modulator or a digital micromirror.

6. The system according to claim 1, characterized in that The output light field acquisition component includes: a Fourier transform lens and a CCD camera. The loaded light beam is subjected to inverse Fourier transform through the Fourier transform lens, and the light spot of the inverse Fourier transformed light beam is captured by the CCD camera at multiple preset positions.

7. A method for generating a transmission invariant structured light field, characterized in that: include: A laser beam is emitted through an input light field generation component, and the laser beam is spatially filtered and expanded to be converted into a fundamental mode Gaussian beam, and the fundamental mode Gaussian beam is transmitted to a light field modulation component; Through the light field modulation component, the dynamic phase hologram obtained by combining the Fourier spectrum of the transmission invariant structure light field at different positions with the corresponding propagation phase for encoding is loaded onto the fundamental mode Gaussian beam; and the loaded beam is transmitted to the output light field acquisition component; The loaded light beam is subjected to inverse Fourier transformation through the output light field acquisition component, and the light spot of the light beam subjected to inverse Fourier transformation is captured at a plurality of preset positions.

8. The method according to claim 7, characterized in that Before transmitting the fundamental mode Gaussian beam to the light field modulation component, the method further includes: The fundamental mode Gaussian light beam is subjected to polarization state conversion and intensity control through a polarization beam splitting component to form a fundamental mode Gaussian light beam with a horizontal polarization state, and is transmitted to the light field modulation component.

9. The method according to claim 8, characterized in that The dynamic phase hologram obtained by encoding the Fourier spectrum of the transmission invariant structure light field at different positions with the corresponding propagation phase is loaded onto the fundamental mode Gaussian beam, comprising: The Fourier spectrum of the transmission invariant structure light field at different positions is combined with the spatial propagation phase to generate a dynamic phase hologram, and the dynamic phase hologram is used to perform complex amplitude modulation on a fundamental mode Gaussian light beam with a horizontal polarization state.

10. The method according to claim 9, characterized in that: The dynamic phase hologram obtained by encoding the Fourier spectrum of the transmission invariant structure light field at different positions with the corresponding propagation phase is loaded onto the fundamental mode Gaussian beam, comprising: Changing the distance between the transmission invariant structure light field and the virtual Fourier transform lens by digital control, and generating phase holograms corresponding to different positions of the transmission invariant structure light field relative to the virtual Fourier transform lens by coding calculation based on a complex amplitude modulation method; The corresponding phase hologram of each position is loaded onto the fundamental mode Gaussian beam with a horizontal polarization state.

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