Preparation method and device of three-dimensional astigmatic beam mask plate

Abstract

The invention relates to a preparation method and device of a three-dimensional caustic beam mask plate, and the method comprises the steps: obtaining reference curve information; calculating light beam distribution shape features based on the reference curve information; determining an annular angular spectrum phase factor based on the light beam distribution shape features; calculating axial distribution characteristics based on the reference curve information and the light beam distribution shape characteristics; determining an axial phase adjustment factor based on the axial distribution characteristics; based on the annular angular spectrum phase factor and the axial phase adjustment factor, a complex transmittance function is determined, and the complex transmittance function is used for providing a phase azimuth angle and a phase change relation when the to-be-modulated light beam passes through the spatial light modulator; and loading the complex transmittance function into the spatial light modulator to form the three-dimensional astigmatic beam mask plate. According to the method and the device, the problem of accurately capturing and transporting particles in the field of three-dimensional space particle manipulation is solved, and the space structure of the three-dimensional astigmatic beam is freely controlled.

Description

Technical Field

[0001] The present application relates to the field of particle manipulation, and particularly to a method and device for preparing a three-dimensional caustic beam mask template. Background Art

[0002] Particle manipulation technology is a technology that precisely controls tiny particles using physical fields such as light, electricity, and magnetism. As a non-contact and non-invasive method, it has received extensive attention in recent years. By precisely designing the shape, intensity, and phase distribution of the light field, various operations such as particle capture, rotation, and translation can be achieved, providing solutions for applications such as particle capture, guidance, and nanodrug transportation.

[0003] In the field of optical caustics, there are already some technologies that can achieve specific structured light fields, such as Airy beams and Pierce beams. These beams have unique optical properties such as self-acceleration, non-diffraction, and self-healing, and have extensive applications in the fields of particle manipulation, microscopy imaging, and optical micromachining. However, these forms of light fields are relatively single and cannot meet the needs of transporting and guiding particles in complex paths. In addition, although optical caustics can be used to customize a structured light field with a rich spatial mode distribution, the spatial structure of these beams is limited to a two-dimensional plane and cannot capture and transport particles in three-dimensional space.

[0004] Currently, in the field of particle manipulation for related technologies, no effective solution has been proposed for the problem of precisely capturing and transporting particles in three-dimensional space. Summary of the Invention

[0005] Embodiments of the present application provide a method and device for preparing a three-dimensional caustic beam mask template to at least solve the problem of how to precisely capture and transport particles in three-dimensional space in the field of particle manipulation for related technologies.

[0006] In a first aspect, embodiments of the present application provide a method for preparing a three-dimensional caustic beam mask template, including:

[0007] Obtaining reference curve information;

[0008] Based on the reference curve information, calculating the beam distribution shape characteristics; based on the beam distribution shape characteristics, determining the annular angular spectrum phase factor;

[0009] Based on the reference curve information and the beam distribution shape characteristics, calculating the axial distribution characteristics; based on the axial distribution characteristics, determining the axial phase adjustment factor;

[0010] Based on the annular angular spectrum phase factor and the axial phase adjustment factor, determining the complex transmittance function, where the complex transmittance function is used to provide the phase azimuth angle and the phase change relationship when the beam to be modulated passes through the spatial light modulator;

[0011] Load the complex transmittance function into the spatial light modulator to form a three-dimensional caustic beam mask template.

[0012] In some embodiments, the reference curve information includes a reference curve azimuth angle and a reference curve position; based on the reference curve information, calculating the beam distribution shape feature includes:

[0013] Calculate a first reference mapping relationship between the annular angular spectrum phase azimuth angle and the target beam shape according to the reference curve azimuth angle and the reference curve position;

[0014] Determine the beam distribution shape feature based on the first reference mapping relationship.

[0015] In some embodiments, based on the beam distribution shape feature, determining the annular angular spectrum phase factor includes:

[0016] Obtain an annular angular spectrum phase factor function;

[0017] Obtain the annular angular spectrum phase factor based on the beam distribution shape feature and the annular angular spectrum phase factor function.

[0018] In some embodiments, the reference curve information includes a reference curve azimuth angle and a reference curve position; based on the reference curve information and the beam distribution shape feature, calculating the axial distribution feature includes:

[0019] Calculate a second reference mapping relationship between the axial phase azimuth angle and the target beam axial position according to the reference curve azimuth angle, the reference curve position, and the beam distribution shape feature;

[0020] Determine the axial distribution feature based on the second reference mapping relationship.

[0021] In some embodiments, based on the axial distribution feature, determining the axial phase adjustment factor includes:

[0022] Obtain an axial phase adjustment factor function;

[0023] Obtain the axial phase adjustment factor based on the axial distribution feature and the axial phase adjustment factor function.

[0024] In some embodiments, based on the annular angular spectrum phase factor and the axial phase adjustment factor, determining the complex transmittance function includes:

[0025] Determine a preset blazed grating and obtain the grating phase factor of the blazed grating;

[0026] Determine the complex transmittance function based on the annular angular spectrum phase factor, the axial phase adjustment factor, and the blazed grating phase factor.

[0027] In some embodiments, the obtaining of the blazed grating phase factor includes:

[0028] Obtain the grating coordinates and the grating phase period of the blazed grating;

[0029] Calculate the grating phase factor according to the grating coordinates and the grating phase period.

[0030] In a second aspect, an embodiment of the present application provides a method for forming a three-dimensional caustic beam, including:

[0031] Irradiate the beam to be modulated onto a three-dimensional caustic beam mask, and modulate the beam to be modulated via the three-dimensional caustic beam mask to form a target three-dimensional caustic beam; the three-dimensional caustic beam mask is prepared according to the preparation method of the three-dimensional caustic beam mask described in any one of the above first aspects.

[0032] In some embodiments, before forming the target three-dimensional caustic beam, the method further includes:

[0033] Perform Fourier transform and focusing processing on the beam to be modulated by a Fourier transform lens to form a target three-dimensional caustic beam.

[0034] In a third aspect, an embodiment of the present application provides a device for preparing a three-dimensional caustic beam mask, including:

[0035] An adjustment factor module, configured to obtain reference curve information;

[0036] The adjustment factor module is further configured to calculate the beam distribution shape feature based on the reference curve information; determine the annular angular spectrum phase factor based on the beam distribution shape feature;

[0037] The adjustment factor module is further configured to calculate the axial distribution feature based on the reference curve information and the beam distribution shape feature; determine the axial phase adjustment factor based on the axial distribution feature;

[0038] A mask generation module, configured to determine a complex transmittance function based on the annular angular spectrum phase factor and the axial phase adjustment factor, where the complex transmittance function is used to provide the phase azimuth angle and the phase change relationship when the beam to be modulated passes through the spatial light modulator;

[0039] The mask generation module is further configured to load the complex transmittance function into the spatial light modulator to form a three-dimensional caustic beam mask.

[0040] Compared with the related art, the method for preparing a three-dimensional caustic beam mask provided by the embodiments of the present application combines an annular angular spectrum phase factor and an axial phase adjustment factor to obtain a complex transmittance function of the three-dimensional caustic beam mask with a freely adjustable structure. Loading this complex transmittance function into a spatial light modulator can obtain the required three-dimensional caustic beam mask, which solves the problem of accurately capturing and transporting particles in the field of three-dimensional particle manipulation and also realizes the free control of the spatial structure of the three-dimensional caustic beam.

[0041] Details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more concise and understandable. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] The drawings described herein are used to provide a further understanding of the present application and form a part of the present application. The illustrative embodiments and descriptions thereof are used to explain the present application and do not constitute an improper limitation of the present application. In the drawings:

[0043] Figure 1 is a hardware structure block diagram of a terminal for the method for preparing a three-dimensional caustic beam mask according to an embodiment of the present invention;

[0044] Figure 2 is a flowchart of the method for preparing a three-dimensional caustic beam mask according to an embodiment of the present application;

[0045] Figure 3 is a schematic diagram of a mask of a three-dimensional caustic beam according to a preferred embodiment of the present application;

[0046] Figure 4 is a preferred embodiment of the present application Figure 3 schematic diagrams of three-dimensional caustic beams with different spatial structures generated by the mask of the three-dimensional caustic beam in;

[0047] Figure 5 is a structure block diagram of a device for preparing a three-dimensional caustic beam mask according to an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] In order to make the objectives, technical solutions and advantages of the present application more clear and understandable, the present application will be described and explained below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments provided in the present application without making creative efforts belong to the scope of protection of the present application. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for those of ordinary skill in the art related to the content disclosed in the present application, some design, manufacturing or production changes based on the technical content disclosed in the present application are only conventional technical means and should not be understood as the content disclosed in the present application being insufficient.

[0049] In the present application, the mention of "embodiment" means that the specific features, structures or characteristics described in connection with the embodiment may be included in at least one embodiment of the present application. The appearance of this phrase in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those of ordinary skill in the art explicitly and implicitly understand that the embodiments described in the present application may be combined with other embodiments without conflict.

[0050] Unless otherwise defined, the technical terms or scientific terms involved in the present application should be of the ordinary meaning understood by those with ordinary skills in the technical field to which the present application belongs. The terms "a", "an", "one kind", "the" and the like involved in the present application do not represent a quantity limitation and may represent a single or plural number. The terms "including", "comprising", "having" and any variations thereof involved in the present application are intended to cover non-exclusive inclusion; for example, a process, method, system, product or device including a series of steps or modules (units) is not limited to the listed steps or units, but may further include steps or units not listed, or may further include other steps or units inherent to these processes, methods, products or devices. The terms "connected", "coupled" and the like involved in the present application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" involved in the present application means greater than or equal to two. "And / or" describes the association relationship of associated objects and indicates that three relationships may exist. For example, "A and / or B" may represent: A exists alone, A and B exist simultaneously, and B exists alone. The terms "first", "second", "third" and the like involved in the present application are only used to distinguish similar objects and do not represent a specific order of the objects.

[0051] The method embodiment provided in this embodiment can be executed on a terminal, a computer or a similar computing device. Taking running on a terminal as an example,Figure 1 It is a hardware structure block diagram of the terminal of the preparation method of the three-dimensional caustic beam mask template according to an embodiment of the present invention. As Figure 1 shown, the terminal may include one or more ( Figure 1 only one is shown in the figure) processors 102 (the processor 102 may include, but is not limited to, a processing device such as a microprocessor MCU or a programmable logic device FPGA) and a memory 104 for storing data. Optionally, the above terminal may further include a transmission device 106 for communication functions and an input / output device 108. Those of ordinary skill in the art can understand that Figure 1 the structure shown is only schematic and does not limit the structure of the above terminal. For example, the terminal may further include more or fewer components than Figure 1 shown in the figure, or have a different configuration from Figure 1 shown in the figure.

[0052] The memory 104 can be used to store computer programs. For example, software programs and modules of application software, such as the computer program corresponding to the preparation method of the three-dimensional caustic beam mask template in the embodiment of the present invention. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, that is, the above method is implemented. The memory 104 may include a high-speed random access memory, and may also include a non-volatile memory, such as one or more magnetic storage devices, flash memories, or other non-volatile solid-state memories. In some instances, the memory 104 may further include a memory remotely disposed relative to the processor 102, and these remote memories may be connected to the terminal through a network. Examples of the above network include, but are not limited to, the Internet, an enterprise intranet, a local area network, a mobile communication network, and combinations thereof.

[0053] The transmission device 106 is used to receive or send data via a network. Specific examples of the above network may include a wireless network provided by a communication provider of the terminal. In one instance, the transmission device 106 includes a network adapter (Network Interface Controller, abbreviated as NIC), which can be connected to other network devices through a base station and thus can communicate with the Internet. In one instance, the transmission device 106 may be a radio frequency (Radio Frequency, abbreviated as RF) module, which is used to communicate with the Internet wirelessly.

[0054] This embodiment provides a method for preparing a three-dimensional caustic beam mask template, Figure 2 which is a flowchart of the method for preparing a three-dimensional caustic beam mask template according to an embodiment of the present application. As Figure 2 shown, the process includes the following steps:

[0055] Step S201, obtaining reference curve information;

[0056] Among them, the target optical field is designed according to the reference curve information, and the reference curve information includes information such as the shape of the reference curve and the position of the reference curve, which are used to characterize the optical characteristics of the reference curve. This information can be obtained through experimental measurement or theoretical calculation, providing basic data for subsequent steps; the reference curve is used to modulate and generate the corresponding mask.

[0057] Step S202: Calculate the shape characteristics of the beam distribution based on the reference curve information; determine the annular angular spectrum phase factor based on the shape characteristics of the beam distribution.

[0058] Among them, according to the reference curve information, the shape characteristics of the beam forming the reference curve are calculated using mathematical methods (such as Fourier transform, diffraction theory, etc.), that is, the transverse distribution characteristics of the beam. The transverse distribution characteristics are the intensity structure distribution of the beam on a specific plane. By processing the transverse distribution characteristics, for example, substituting the transverse distribution characteristics into the expression of the obtained annular angular spectrum phase factor, through a series of integral operations, the required annular angular spectrum phase factor is obtained. The function of the annular angular spectrum phase factor is the azimuth angle of the transverse parameters (x and y) of the beam and the annular spectrum phase Related expressions. By calculating the shape characteristics of the beam distribution in this step, the transverse structure of the three-dimensional caustic beam can be precisely controlled. The determination of the annular angular spectrum phase factor can form specific caustic structures, such as folding mutations, cusp mutations, etc.

[0059] Step S203: Calculate the axial distribution characteristics based on the reference curve information and the shape characteristics of the beam distribution; determine the axial phase adjustment factor according to the axial distribution characteristics.

[0060] Among them, when calculating the axial distribution characteristics, the wavelength λ of the beam forming the reference curve in the reference curve information and other factors will be considered. These factors jointly determine the focusing and defocusing behaviors of the beam. By combining these parameters with the shape characteristics of the beam distribution, the axial position of the beam at different angles can be calculated, thereby obtaining the axial distribution characteristics, that is, the intensity distribution and phase distribution of the beam at the axial position; the axial phase adjustment factor is calculated based on the axial distribution characteristics. The expression of the axial phase adjustment factor is a function related to the phase azimuth angle Related functions, which are used to adjust the phase of the beam at different angles to achieve the required three-dimensional caustic structure optical field. By precisely controlling the axial phase adjustment factor, specific caustic structures, such as folding mutations, cusp mutations, etc., can be formed. The introduction of the axial phase adjustment factor enables the formed caustic structure to be freely regulated in three-dimensional space, realizing the precise manipulation of three-dimensional beams and being able to form various complex caustic structures, providing more possibilities for fields such as particle trapping, laser processing, and microscopic imaging.

[0061] Step S204: Determine the complex transmittance function based on the annular angular spectrum phase factor and the axial phase adjustment factor. The complex transmittance function is used to provide the phase azimuth angle and the phase change relationship when the beam to be modulated passes through the spatial light modulator.

[0062] Among them, by combining the annular angular spectrum phase factor and the axial phase adjustment factor, the complex transmittance function of the mask is obtained, that is, a composite phase modulation function is formed. The complex transmittance function describes the phase azimuth angle and the phase change relationship when the beam to be modulated passes through the spatial light modulator. The determination of the complex transmittance function enables the spatial light modulator to accurately modulate the phase distribution of the beam, thereby generating the expected three-dimensional caustic beam. By adjusting the annular angular spectrum phase factor and the axial phase adjustment factor in the complex transmittance function, the spatial structure and characteristics of the three-dimensional caustic beam can be flexibly controlled.

[0063] Step S205: Load the complex transmittance function into the spatial light modulator to form a three-dimensional caustic beam mask.

[0064] Among them, the complex transmittance function is loaded into the control system of the spatial light modulator through a computer program. The spatial light modulator performs phase modulation on the incident beam according to the complex transmittance function to form a three-dimensional caustic beam mask. By loading the complex transmittance function into the spatial light modulator, a three-dimensional caustic beam with a specific spatial structure can be generated in real time and accurately. The three-dimensional caustic beam has broad application prospects in the field of particle manipulation. Its adjustable transverse intensity and curved trajectory distribution greatly facilitate the precise manipulation of microparticles, enabling diverse capture modes and transmission paths for cells, bacteria, or nanoparticles, etc.

[0065] Through the above steps, based on the obtained reference curve information, the shape characteristics of the beam distribution are calculated, and then the annular angular spectrum phase factor is determined. In the traditional technology, the shape of the beam is often regulated by fixed optical elements (such as lenses, mirrors, etc.), which limits the flexibility and tunability of the beam shape. However, in this application, by calculating the annular angular spectrum phase factor, precise regulation of the beam shape is achieved, and this regulation is programmable and dynamically adjustable; further, based on the reference curve information and the beam distribution shape characteristics, the axial distribution characteristics are calculated, and the axial phase adjustment factor is determined. This factor is used to control the axial distribution of the beam, thereby achieving the defocusing effect of the three-dimensional caustic beam. In the traditional technology, the axial distribution of the beam is usually adjusted by changing the focal length of the lens or moving the distance between the light source and the lens. This method is cumbersome to operate and has limited precision. However, in this application, by calculating the axial phase adjustment factor, precise control of the axial distribution of the beam is achieved, and this control is also programmable and dynamically adjustable; then, by combining the annular angular spectrum phase factor and the axial phase adjustment factor, the complex transmittance function is determined, and the complex transmittance function is loaded into the spatial light modulator to form a three-dimensional caustic beam mask. Compared with the related technology, this application realizes precise regulation of the shape and axial distribution of the three-dimensional caustic beam by introducing the annular angular spectrum phase factor and the axial phase adjustment factor, which not only improves the complexity and diversity of the beam, but also provides more possibilities for fields such as particle trapping, laser processing, and nano-drug transportation.

[0066] In some of these embodiments, the reference curve information includes the reference curve azimuth angle and the reference curve position;

[0067] Based on the reference curve information, calculating the beam distribution shape characteristics includes:

[0068] According to the reference curve azimuth angle and the reference curve position, calculate the first reference mapping relationship between the annular angular spectrum phase azimuth angle and the target beam shape;

[0069] Based on the first reference mapping relationship, determine the beam distribution shape characteristics.

[0070] Among them, the reference curve azimuth angle θ is the target light field structure azimuth angle θ, and the reference curve position refers to the specific position (x, y) of the reference curve in space. The reference curve azimuth angle and the reference curve position are determined by the conversion between polar coordinates and rectangular coordinates, that is, x = rcosθ, y = rsinθ. There is the following conversion relationship between the reference curve azimuth angle θ, the reference curve polar axis radius r, and the annular angular spectrum phase azimuth angle There is the following conversion relationship:

[0071]

[0072] According to the above formula and by using a mathematical model or algorithm, calculate the azimuth angle of the annular spectral phase corresponding to the first reference mapping relationship f(x,y) (i.e., the shape function of the target beam). The overall idea is to modulate and generate the target beam according to the reference curve, so as to obtain the target light field. The first reference mapping relationship is the mapping relationship between the annular angular spectral phase position (specifically, the transverse parameters x and y of the target beam) and the azimuth angle of the annular angular spectral phase between, for example, the shape functions f(x,y) of different three-dimensional caustic beams can be f(acosθ, asinθ), and so on. Based on the first reference mapping relationship, the characteristics of the azimuth angle of the annular spectral phase can be determined through the reference curve / beam structure, so as to generate the corresponding light field by using this phase modulation. The beam distribution shape characteristics include the shape function f(x,y). In this embodiment, by establishing the mapping relationship between the azimuth angle of the annular angular spectral phase and the shape of the target beam (the structure and position of the target beam), the precise control of the beam spatial structure can be realized, providing the possibility for realizing complex particle manipulation tasks; by optimizing the beam distribution shape characteristics of the mask, the modulation accuracy and freedom of the mask used to modulate and form the target three-dimensional caustic beam are effectively improved.

[0073] In some of these embodiments, based on the beam distribution shape characteristics, determining the annular angular spectral phase factor includes:

[0074] Obtain the annular angular spectral phase factor function; based on the beam distribution shape characteristics and the annular angular spectral phase factor function, obtain the annular angular spectral phase factor.

[0075] Among them, the annular angular spectral phase factor function is determined by mathematical derivation of the reference curve information; then according to the shape function f(x,y) determined by the above conversion relationship between the azimuth angle θ of the reference curve, the polar axis radius r of the reference curve and the azimuth angle of the annular angular spectral phase between, substitute the shape function f(x,y) into the annular angular spectral phase factor function, and calculate the annular angular spectral phase factor through integral operation. When a specific value of θ is substituted, the annular angular spectral phase factor can be a specific value; when an expression about θ is substituted, the obtained annular angular spectral phase factor is also an expression about . The specific expression of its annular angular spectral phase factor function is:

[0076]

[0077] In the above expression, φ t is the annular angular spectral phase factor, x and y are the transverse parameters of the beam in the rectangular coordinate system, is the azimuth angle of the annular spectral phase required to obtain the target beam.

[0078] In this embodiment, by changing the shape function f(x, y), the spatial structure of the three-dimensional caustic beam can be flexibly regulated, providing the possibility for realizing complex particle manipulation. By calculating through the function of the annular angular spectrum phase factor, the beam structure characteristics can be accurately controlled, thereby improving the accuracy and efficiency of particle manipulation.

[0079] In some of these embodiments, the reference curve information includes the reference curve azimuth angle and the reference curve position; based on the reference curve information and the beam distribution shape characteristics, the axial distribution characteristics are calculated, including:

[0080] According to the reference curve azimuth angle, the reference curve position, and the beam distribution shape characteristics, calculate the second reference mapping relationship between the axial phase azimuth angle and the axial position of the target beam;

[0081] Based on the second reference mapping relationship, determine the axial distribution characteristics.

[0082] Among them, the reference curve azimuth angle θ is the target light field structure azimuth angle θ, and the reference curve position refers to the specific position (x, y) of the reference curve in space. The reference curve azimuth angle and the reference curve position are determined by the conversion between polar coordinates and rectangular coordinates, that is, x = rcosθ, y = rsinθ. Along the beam distribution shape characteristics, combined with the conversion relationship between the reference curve azimuth angle θ, the reference curve polar axis radius r, and the axial phase azimuth angle The second reference mapping relationship is calculated through mathematical reasoning. The second reference mapping relationship is the mapping relationship between the axial position of the target beam and the axial phase azimuth angle For example, the shape function f(x, y) of different three-dimensional caustic beams and the defocusing function defined along the shape function f(x, y) can be: shape function f(acosθ, asinθ), defocusing function shape function f(aθcos(10θ), aθsin(10θ)), defocusing function According to the second reference mapping relationship, the distribution characteristics of the target beam in the axial direction (i.e., perpendicular to the beam propagation direction), that is, the axial distribution characteristics, can be determined. The axial distribution characteristics include the defocusing function

[0083] This embodiment combines the azimuth angle of the reference curve, the position of the reference curve, and the characteristics of the beam distribution shape to achieve precise control of the position of the target three-dimensional caustic beam. Through an algorithm or a mathematical model, the three-dimensional curve position is associated with the target beam position, the mapping relationship between the azimuth angle of the reference curve and the annular spectral phase is calculated, and a direct connection between the azimuth angle of the reference curve and the target beam position is established. By determining the axial distribution characteristics, the design parameters of the mask can be further adjusted to optimize the performance of the three-dimensional caustic beam, improving the flexibility and accuracy of particle manipulation.

[0084] In some of these embodiments, based on the axial distribution characteristics, an axial phase adjustment factor is determined, including:

[0085] Obtain the axial phase adjustment factor function;

[0086] Based on the axial distribution characteristics and the axial phase adjustment factor function, the axial phase adjustment factor is obtained.

[0087] Among them, the axial phase adjustment factor function φ is determined by mathematical derivation of the reference curve information a , and then according to the defocus function determined above and the focal length f of the focusing lens and the beam wavelength λ in the reference curve information, substituting them into the axial phase adjustment factor function, the axial phase adjustment factor is calculated through integral operation. The same as the annular angular spectrum phase factor, the axial phase adjustment factor can be an expression or a specific value. The specific expression of the axial phase adjustment factor function φ a is:

[0088]

[0089] In the above expression, φ a is the axial phase adjustment factor; f is the focal length of the focusing lens; λ is the wavelength of the beam; is the defocus function.

[0090] This embodiment can achieve precise control of the beam in the axial direction by specifically calculating the axial phase adjustment factor, not limited to simple focusing and defocusing, but also including more complex three-dimensional structures such as bending and twisting, providing more degrees of freedom for particle manipulation, enabling more precise capture, transportation, and manipulation of particles in three-dimensional space; the use of the axial phase adjustment factor can also enhance the stability and anti-interference ability of the beam. During the particle manipulation process, small changes in the external environment may cause the beam to shift or deform. By calculating the axial phase adjustment factor to precisely control the axial phase, these effects can be offset to a certain extent, maintaining the stability and accuracy of the beam.

[0091] In some of these embodiments, determining the complex transmittance function based on the annular angular spectrum phase factor and the axial phase adjustment factor includes:

[0092] Determine a preset blazed grating and obtain the grating phase factor of the blazed grating;

[0093] Determine the complex transmittance function based on the annular angular spectrum phase factor, the axial phase adjustment factor, and the blazed grating phase factor.

[0094] Among them, the blazed grating is an optical element with periodic phase changes, used to separate the required three-dimensional caustic beam from the zero-order spot. Its phase period d determines the separation of diffraction orders. Specifically, it is necessary to select a suitable blazed grating according to the experimental conditions and the characteristics of the required three-dimensional caustic beam. Through the preset parameter information related to the blazed grating, calculate the grating phase factor F of the blazed grating. Combining the annular angular spectrum phase factor, the axial phase adjustment factor, and the blazed grating phase factor, the complex transmittance function of the three-dimensional caustic beam mask is obtained. The specific expression of the function is:

[0095] t c = exp(i·(φ t + φ a + F))

[0096] In the above expression, φ t is the annular angular spectrum phase factor; φ a is the axial phase adjustment factor; F is the blazed grating phase factor; i is the imaginary unit; loading this complex transmittance function into a spatial light modulator by a computer can generate a mask for a three-dimensional caustic beam with a freely adjustable spatial structure.

[0097] In this embodiment, the introduction of the blazed grating enables the separation of the required three-dimensional caustic beam from the zero-order spot. The separation effect of the blazed grating ensures the purity of the beam, improves the quality of the three-dimensional caustic beam, and can also conveniently screen out the required beam, further enhancing the beam control ability of the mask, making the generated three-dimensional caustic beam have a richer spatial structure; by combining the annular angular spectrum phase factor and the axial phase adjustment factor, the free control of the spatial structure of the three-dimensional caustic beam can be achieved.

[0098] In some of these embodiments, obtaining the blazed grating phase factor includes:

[0099] Obtain the grating coordinates and the grating phase period of the blazed grating;

[0100] Calculate the grating phase factor according to the grating coordinates and the grating phase period.

[0101] Among them, the grating phase factor F is calculated by the grating phase period d of the blazed grating and the transverse parameter x (grating coordinate) in the rectangular coordinate system. In the design of the mask, the blazed grating is usually defined on a two-dimensional plane, so it is necessary to determine the coordinates of the grating on this plane; the phase period d determines the separation of diffraction orders, and the phase period of the grating can be determined by measurement or calculation. The specific expression of the function for calculating the grating phase factor is as follows:

[0102]

[0103] In the above expression, d is the phase period of the blazed grating; x is the transverse parameter of the blazed grating in the rectangular coordinate system; F is the grating phase factor.

[0104] Accurately obtaining the grating coordinates and the grating phase period in this embodiment is the basis for designing the blazed grating, which directly affects the diffraction effect of the grating and the beam control ability. By precisely controlling the coordinates and period of the grating, precise control of the beam can be achieved, thereby meeting specific application requirements; by calculating the grating phase factor, precise control of the grating diffraction effect can be realized, and by combining the grating phase factor with the annular angular spectrum phase factor and the axial phase adjustment factor, a mask for a three-dimensional caustic beam with a complex spatial structure can be designed.

[0105] This embodiment also provides a method for forming a three-dimensional caustic beam, including:

[0106] Irradiating the beam to be modulated onto the three-dimensional caustic beam mask, and modulating the beam to be modulated via the three-dimensional caustic beam mask to form a target three-dimensional caustic beam; the three-dimensional caustic beam mask is prepared according to the preparation method of the three-dimensional caustic beam mask in any one of the above embodiments.

[0107] Among them, the beam to be modulated (such as a parallel beam) is irradiated onto a three-dimensional caustic beam mask. The three-dimensional caustic beam mask is prepared according to the method described in the embodiments of the reference materials. The mask combines an annular angular spectrum phase factor, an axial phase adjustment factor, and a blazed grating, which act together on the beam to be modulated. After being modulated by the three-dimensional caustic beam mask and passing through a Fourier transform lens, a target three-dimensional caustic beam is formed. In this method, due to the design of the mask combining multiple control factors, the beam can be accurately controlled in both the two-dimensional plane and the three-dimensional space. The introduction of the annular angular spectrum phase factor and the axial phase adjustment factor enables the free control of the spatial structure of the beam, meeting the requirements of different application scenarios. The separation effect of the blazed grating ensures the purity of the beam and improves the quality of the three-dimensional caustic beam. The method provided in this embodiment, through the combined action of the mask and optical elements, finally forms a three-dimensional caustic beam with a specific spatial structure, realizing important applications of the three-dimensional caustic beam in the field of particle manipulation, such as particle capture, rotation, and transportation in three-dimensional space, providing a new means for scientific research and technological applications.

[0108] In some of these embodiments, before forming the target three-dimensional caustic beam, it further includes:

[0109] The Fourier transform lens performs Fourier transform and focusing processing on the beam to be modulated to form the target three-dimensional caustic beam.

[0110] Among them, the beam modulated by the phase mask passes through the Fourier transform lens, and the target three-dimensional caustic beam is formed on the rear focal plane of the Fourier lens, thus obtaining the target light field. In this embodiment, the Fourier transform lens performs Fourier transform and focusing processing on the beam to be modulated to generate a target three-dimensional caustic beam with a specific spatial structure. The focusing processing makes the beam form a clear image at a specific position, facilitating observation and measurement.

[0111] The embodiments of the present application will be described and illustrated below through preferred embodiments.

[0112] Figure 3 is a schematic diagram of the mask of the three-dimensional caustic beam according to the preferred embodiment of the present application, as Figure 3 shown. The preparation method of this three-dimensional caustic beam mask is as follows:

[0113] Combined with an annular angular spectrum phase factor, an axial phase adjustment factor, and a blazed grating, the complex transmittance function t of the three-dimensional caustic beam mask with a freely adjustable structure is obtained c , and its specific expression of the complex amplitude transmittance function is:

[0114] t c = exp(i·(φ t + φ a + F))

[0115] Among them, φ t is the annular angular spectrum phase factor; φ a is the axial phase adjustment factor; F is the blazed grating phase factor. By loading this complex transmittance function into the spatial light modulator through a computer, a mask for a three-dimensional caustic beam with a freely adjustable spatial structure can be generated.

[0116] The annular angular spectrum phase factor φ t has the following expression:

[0117]

[0118] Among them, is the azimuth angle of the annular spectrum phase, and x and y are the transverse parameters of the preset light field shape in the rectangular coordinate system. is the set shape function. After integral operation, the required annular angular spectrum phase factor can be obtained.

[0119] The axial phase adjustment factor φ a has the following expression:

[0120]

[0121] is the defocus function defined along the shape function , f is the focal length of the focusing lens, and λ is the wavelength.

[0122] The expression of the blazed grating F mentioned above is:

[0123]

[0124] Among them, d is the phase period of the blazed grating, and x is the transverse parameter of the blazed grating in the rectangular coordinate system. In the experimental generation of a three-dimensional caustic beam with a freely adjustable spatial structure, the role of this blazed grating is to separate the required three-dimensional caustic beam from the zero-order spot.

[0125] In the experiment, parallel light is irradiated on the spatial light modulator of the input mask for a freely adjustable three-dimensional caustic beam. The beam reflected by the spatial light modulator passes through the Fourier transform lens, and the required freely adjustable three-dimensional caustic beam can be obtained in the far field. In addition, the period d of the blazed grating can be adjusted to separate the three diffraction orders until the +1 diffraction order can be selected using a diaphragm, and thus a three-dimensional caustic beam with a freely adjustable spatial structure can be obtained.

[0126] Figure 3 is a schematic diagram of the mask for a three-dimensional caustic beam according to a preferred embodiment of the present application. In Figure 3 :

[0127] (a) The shape function is f(acosθ, asinθ), and the defocus function

[0128] (b) The shape function is f(aθcos(10θ), aθsin(10θ)), and the defocus function z = 0.5 - (1 - θ 2 ) 0.5 ;

[0129] (c) The shape function is f(a(cosθ - 2cos(2θ)), a(sinθ - 2sin(2θ))), and the defocus function z = sin(3θ);

[0130] Figure 4 is a schematic diagram of three - dimensional caustic beams with different spatial structures generated by the mask of the preferred embodiment of this application, as Figure 3 shown: Figure 4 shown

[0131] (a1)-(a3) are the intensity distributions of the tilted circular three - dimensional caustic beam at the front focal plane, focal plane, and rear focal plane;

[0132] (b1)-(b3) are the intensity distributions of the Archimedean spiral three - dimensional caustic beam at the front focal plane, focal plane, and rear focal plane;

[0133] (c1)-(c3) are the intensity distributions of the clover - shaped three - dimensional caustic beam at the front focal plane, focal plane, and rear focal plane.

[0134] Specifically, taking a mask with a size of 512×512 as an example, a mask for three - dimensional caustic beams with freely adjustable spatial structures is given for a laser with a working wavelength of 632 nm. According to the mask complex transmittance function in the specific implementation manner, a mask for three - dimensional caustic beams with freely adjustable spatial structures is finally obtained. Figure 3 That is the mask for three - dimensional caustic beams with freely adjustable spatial structures used in the embodiment. Such a mask for three - dimensional caustic beams with freely adjustable spatial structures can be realized by a spatial light modulator. Taking the PLUTO - VIS - 016 type phase - type spatial light modulator of German Holoeye company as an example, its pixel size is 8μm, the fill factor is 93%, and the resolution is 1920 pixel×1080 pixel. A continuous - wave solid - state laser with a wavelength of 632 nm and a power of 50 mW is used in the experiment.

[0135] Figure 4 is the light intensity distribution of the three - dimensional caustic beam with freely adjustable spatial structures generated in the embodiment on the focal plane of a lens with a numerical aperture of 0.05. From Figure 4It can be seen that as the position of the CCD changes, the spatial structure of the light beam also changes accordingly and exhibits an obvious defocus phenomenon. This indicates that we have generated a three-dimensional caustic beam with a freely adjustable spatial structure, which will provide an additional degree of freedom for particle trapping and rotation.

[0136] This embodiment also provides a device for preparing a three-dimensional caustic beam mask template. This device is used to implement the above-mentioned embodiments and preferred implementation manners, and those that have been described will not be repeated here. As used below, terms such as "module", "unit", "sub-unit", etc. can be a combination of software and / or hardware that can achieve a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware is also possible and contemplated.

[0137] Figure 5 is a structural block diagram of a device for preparing a three-dimensional caustic beam mask template according to an embodiment of the present application. As Figure 5 shown, the device includes:

[0138] Adjustment factor module 10, used to obtain reference curve information;

[0139] The above adjustment factor module 10 is also used to calculate the light beam distribution shape characteristics based on the reference curve information; and determine the annular angular spectrum phase factor based on the light beam distribution shape characteristics;

[0140] The above adjustment factor module 10 is also used to calculate the axial distribution characteristics based on the reference curve information and the light beam distribution shape characteristics; and determine the axial phase adjustment factor based on the axial distribution characteristics;

[0141] Mask template generation module 20, used to determine the complex transmittance function based on the annular angular spectrum phase factor and the axial phase adjustment factor. The complex transmittance function is used to provide the phase azimuth angle and the phase change relationship when the beam to be modulated passes through the spatial light modulator;

[0142] The above mask template generation module 20 is also used to load the complex transmittance function into the spatial light modulator to form a three-dimensional caustic beam mask template.

[0143] It should be noted that the above-mentioned each module can be a functional module or a program module, and can be implemented either by software or by hardware. For the modules implemented by hardware, the above-mentioned each module can be located in the same processor; or the above-mentioned each module can also be located in different processors in any combined form.

[0144] Those skilled in the art should understand that the technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity in description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification.

[0145] The above-described embodiments only express several implementation manners of the present application, and the description thereof is relatively specific and detailed. However, it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A method for preparing a three-dimensional caustic beam mask, characterized in that: include: Get reference curve information; Based on the reference curve information, calculating the beam distribution shape characteristics; Determining an annular angular spectrum phase factor based on the beam distribution shape characteristics; Calculating axial distribution characteristics based on the reference curve information and the beam distribution shape characteristics; Based on the axial distribution characteristics, determining an axial phase adjustment factor; Based on the annular angular spectrum phase factor and the axial phase adjustment factor, a complex transmittance function is determined, wherein the complex transmittance function is used to provide a phase azimuth angle and a phase change relationship when the light beam to be modulated passes through the spatial light modulator; The complex transmittance function is loaded into the spatial light modulator to form a three-dimensional caustic beam mask.

2. The method for preparing a three-dimensional caustic beam mask according to claim 1, characterized in that: The reference curve information includes a reference curve azimuth and a reference curve position; and the calculation of the beam distribution shape characteristics based on the reference curve information includes: Calculating a first reference mapping relationship between annular angular spectrum phase azimuth and target beam shape according to the reference curve azimuth and the reference curve position; Based on the first reference mapping relationship, the light beam distribution shape characteristics are determined.

3. The method for preparing a three-dimensional caustic beam mask according to claim 2, characterized in that: The step of determining the annular angular spectrum phase factor based on the beam distribution shape characteristics comprises: Obtain the annular angular spectrum phase factor function; The annular angular spectrum phase factor is obtained based on the beam distribution shape characteristics and the annular angular spectrum phase factor function.

4. The method for preparing a three-dimensional caustic beam mask according to claim 1, characterized in that: The reference curve information includes a reference curve azimuth and a reference curve position; and the calculating of the axial distribution characteristics based on the reference curve information and the beam distribution shape characteristics includes: Calculating a second reference mapping relationship between the axial phase azimuth and the axial position of the target light beam according to the reference curve azimuth, the reference curve position and the light beam distribution shape characteristics; The axial distribution feature is determined based on the second reference mapping relationship.

5. The method for preparing a three-dimensional caustic beam mask according to claim 1, characterized in that: Based on the axial distribution characteristics, Determine the axial phase adjustment factor, including: Obtaining an axial phase adjustment factor function; The axial phase adjustment factor is obtained based on the axial distribution characteristics and the axial phase adjustment factor function.

6. The method for preparing a three-dimensional caustic beam mask according to claim 1, characterized in that: The determining of the complex transmittance function based on the annular angular spectrum phase factor and the axial phase adjustment factor comprises: Determining a preset blazed grating, and obtaining a grating phase factor of the blazed grating; A complex transmittance function is determined based on the annular angular spectrum phase factor, the axial phase adjustment factor and the blazed grating phase factor.

7. The method for preparing a three-dimensional caustic beam mask according to claim 6, characterized in that: The step of obtaining the blazed grating phase factor comprises: Obtaining the grating coordinates and grating phase period of the blazed grating; The grating phase factor is calculated according to the grating coordinates and the grating phase period.

8. A three-dimensional caustic beam forming method, characterized in that: include: The light beam to be modulated is irradiated onto a three-dimensional caustic beam mask plate, and the light beam to be modulated is modulated by the three-dimensional caustic beam mask plate to form a target three-dimensional caustic beam; the three-dimensional caustic beam mask plate is prepared according to the preparation method of the three-dimensional caustic beam mask plate as described in any one of claims 1 to 7.

9. The three-dimensional caustic beam forming method according to claim 8, characterized in that: Before forming the target three-dimensional caustic beam, the method further includes: The light beam to be modulated is subjected to Fourier transform and focusing processing by a Fourier change lens to form a target three-dimensional caustic light beam.

10. A device for preparing a three-dimensional caustic beam mask, characterized in that: include: Adjustment factor module, used to obtain reference curve information; The adjustment factor module is also used to calculate the beam distribution shape characteristics based on the reference curve information; Determining an annular angular spectrum phase factor based on the beam distribution shape characteristics; The adjustment factor module is also used to calculate the axial distribution characteristics based on the reference curve information and the beam distribution shape characteristics; Based on the axial distribution characteristics, determining an axial phase adjustment factor; A mask template generation module, used to determine a complex transmittance function based on the annular angular spectrum phase factor and the axial phase adjustment factor, wherein the complex transmittance function is used to provide a phase azimuth angle and a phase change relationship when the light beam to be modulated passes through the spatial light modulator; The mask generation module is also used to load the complex transmittance function into the spatial light modulator to form a three-dimensional caustic light beam mask.

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