Astigmatic coherent engineering-based longitudinal double-light-trap particle manipulation method and device

Abstract

The invention relates to the technical field of particle capture and manipulation, in particular to a longitudinal double-light-trap particle manipulation method and device based on astigmatic coherent engineering. The method comprises the following steps: modulating an incident light field by using a binary grating to generate an astigmatic non-uniform partially coherent light beam; focusing the astigmatic non-uniform partially coherent light beam, and changing optical radiation force generated by interaction of momentum carried by the astigmatic non-uniform partially coherent light beam and a substance by regulating and controlling light field distribution of the focused astigmatic non-uniform partially coherent light beam, so that a plurality of optical potential wells are generated near a geometric focus; the optical potential well captures and longitudinally manipulates the particles by regulating and controlling the associated structure, and the capturing and manipulating process is observed in real time through the imaging system. According to the invention, multi-dimensional space capture and accurate control of the micro-nano particles can be realized.

Description

Technical Field

[0001] The present invention relates to the technical field of particle capture and manipulation, and in particular to a method and device for particle manipulation based on astigmatic coherent engineering longitudinal double light traps. Background Art

[0002] Optical tweezers technology uses the energy conversion between light field and matter to achieve precise manipulation of microscopic particles, and is widely used in biomedicine, nanotechnology, quantum science and other fields. However, traditional optical tweezers technology has limitations. It mainly relies on a single beam of light field for lateral manipulation, usually can only form a single light trap, and requires a high-precision three-dimensional motion platform, which makes the experimental process complicated and time-consuming.

[0003] Structured light exhibits unique optical properties by regulating the amplitude, phase, and polarization state of the light field, providing an innovative solution to overcome the limitations of traditional optical tweezers technology. Although the application of spatially structured light beams in particle capture has been widely studied in recent years, most studies still focus on lateral manipulation, and longitudinal capture and manipulation usually rely on three-dimensional motion platforms or delayed feedback systems. Achieving efficient capture and precise manipulation of longitudinal multi-light traps in complex environments is still an important scientific problem that needs to be solved in the current field of optical micromanipulation.

[0004] At present, a variety of fully coherent and partially coherent light beams have been proposed for particle capture research, including: vortex beams generated by laser irradiation of metasurfaces, using their orbital angular momentum to capture and manipulate particles in the lateral dimension; partially coherent vortex beams and Laguerre-Gaussian correlated Schermer beams generated by spatial light modulators, which are used to capture particles and adjust the intensity and range of the light trap through coherence regulation; according to patent CN112652417A, specially correlated partially coherent beams are used to capture and manipulate particles.

[0005] However, the above technology still has the following shortcomings:

[0006] First, there is the problem of precision in the preparation of metasurface devices: the preparation of metasurface devices requires nanoscale processing precision, the yield rate is low, and the fully coherent light beam is limited to lateral manipulation.

[0007] Second, there is the problem of the correlation structure of the partially coherent light beam: the correlation structure of the partially coherent light beam generated by the spatial light modulator is simple, and the longitudinal control depends on external mechanical devices.

[0008] Third, the light trap degradation problem: as the coherence increases, the light trap generated by the partially coherent beam will degenerate and lose its light trap properties. Summary of the invention

[0009] Therefore, the technical problem to be solved by the present invention is to overcome the problems in the prior art that the light trap is degraded due to the improvement of coherence and the longitudinal control depends on external mechanical devices.

[0010] To solve the above technical problems, the present invention provides a method and device for longitudinal dual optical trap particle manipulation based on astigmatic coherent engineering, and the method includes the following steps:

[0011] S1: Modulate the incident light field using a binary grating to generate an astigmatic non-uniform partially coherent beam;

[0012] S2: Focus the astigmatic non-uniform partially coherent beam, and change the optical radiation force generated by the interaction between the momentum carried by it and matter by regulating the light field distribution of the focused astigmatic non-uniform partially coherent beam, so as to generate multiple optical potential wells near the geometric focus;

[0013] S3: The optical potential well captures and longitudinally manipulates the particles by regulating the correlation structure, and the capture and manipulation process is observed in real time through an imaging system.

[0014] In an embodiment of the present invention, in S1, the method for generating an astigmatic non-uniform partially coherent beam is as follows:

[0015] By analyzing the electric field component of the incident light field, the cross-spectral density function of the statistically stationary random scalar beam in the spatial frequency domain is obtained:

[0016] (1),

[0017] wherein, and represent the random electric field components in the vector field, and represent the arbitrary spatial position vectors on the cross-section of the light source, < > represents the ensemble average processing, and * represents the complex conjugate operation;

[0018] Convert the formula (1) into the cross-spectral density function in the superposition form of the integral kernel:

[0019] (2),

[0020] wherein, represents an arbitrary integral kernel function, r represents the position vector on the cross-section of the light source, r includes and , represents the non-negative weight function of the integral kernel function, and the Fourier space parameter , is an arbitrary vector in the Fourier space;

[0021] Discretize the Fourier space parameter v to obtain a finite set of a series of uncorrelated and completely coherent modes, that is, the cross-spectral density of the astigmatic non-uniform partially coherent beam:

[0022] (3),

[0023] where M is the number of discrete samples, and m is the annotation of a single pattern among them. is the unit interval after discrete processing of the Fourier space parameter v. represents a discrete pseudo-pattern, corresponding to in the weight function the pattern weight value.

[0024] In an embodiment of the present invention, the integral kernel function is:

[0025] (4),

[0026] where i is the imaginary unit, λ is the wavelength, is a function related to the position vector r, is proportional to and is a real constant, and the complex amplitude function , is the beam waist size of the light beam.

[0027] In an embodiment of the present invention, the non-negative weight function is as follows:

[0028] (5),

[0029] where a is a positive real constant that determines the waist width of the weight function.

[0030] In an embodiment of the present invention, the spectral coherence degree of the astigmatic non-uniform partially coherent light beam is:

[0031] (6),

[0032] where , r is the position vector, ([[]] r 1 s - r 2 s ) represents the difference in the r 1 and r 2 orders of any two points s in space, x 1 and y 1 arer 1 Two orthogonal components of x 2 and y 2 are r 2 two orthogonal components of; u represents the cross factor, represents the coherence length, a is a positive real constant that determines the waist width of the weighting function, is a real constant, is the wave number, i is the imaginary unit.

[0033] In one embodiment of the present invention, in S2, the method for generating multiple optical potential wells near the geometric focus is as follows:

[0034] Transmit the astigmatic inhomogeneous partially coherent beam from the input plane of the lens to the target plane at a distance z from it, and the cross-spectral density function at the target plane is expressed as:

[0035] (7),

[0036] Focus the astigmatic inhomogeneous partially coherent beam through the lens focusing system, and the transfer matrix of the lens focusing system is:

[0037] (8),

[0038] Substitute Equation (8) into Equation (7), when ρ1 = ρ2, the intensity of the focused astigmatic inhomogeneous partially coherent beam is obtained I (ρ,z)= W (ρ1,ρ2, z );

[0039] The momentum carried by the focused astigmatic inhomogeneous partially coherent beam generates optical radiation force when interacting with matter, and the optical radiation force includes scattering force and gradient force;

[0040] By regulating the light field distribution of the astigmatic inhomogeneous partially coherent beam, make the gradient force distribution generate a force balance point, and the gradient force intensity at this force balance point is greater than the scattering force. The particles near the geometric focus are restricted to different specified positions in the light field, and multiple optical potential wells are formed longitudinally;

[0041] Among them, G( ) represents the Green's function, , A, B, C, D are the transfer matrix elements, f is the focal length of the lens, I is the unit light intensity, represents the transverse position vector at the target plane z, ρ1 and ρ2 represent any transverse position vectors at the target plane z, and z is the beam propagation distance, where λ is the beam wavelength, k is the beam wave number, and i is the imaginary unit.

[0042] In one embodiment of the present invention, the scattering force is as follows:

[0043] (9),

[0044] where represents the scattering cross section, represents the unit vector along the propagation direction, n is the refractive index of the surrounding ambient medium, I0 is the light intensity at the beam exit surface, c represents the speed of light in vacuum.

[0045] In one embodiment of the present invention, the gradient force is as follows:

[0046] (10),

[0047] where γ nrel represents the relative refractive index, , np is the refractive index of the particle, n is the refractive index of the surrounding ambient medium, ∇I0 represents the gradient of the light intensity at the beam exit surface, R is the particle radius, c represents the speed of light in vacuum.

[0048] Based on the same inventive concept, the present invention also provides a device for longitudinal dual optical trap particle manipulation based on astigmatic coherent engineering, to implement the method for longitudinal dual optical trap particle manipulation based on astigmatic coherent engineering. The device includes:

[0049] An astigmatic non-uniform partially coherent beam generation component, including a helium-neon laser, a digital micromirror device, a grating generator, and a 4f filtering system; the digital micromirror device is arranged on the transmission path of the fully coherent laser beam emitted by the helium-neon laser, the binary grating generated by the grating generator is loaded on the digital micromirror device, the modulated beam is obtained after the interaction between the fully coherent laser beam and the binary grating, the 4f filtering system is arranged on the transmission path of the modulated beam, and the astigmatic non-uniform partially coherent beam is generated by the modulated beam passing through the 4f filtering system;

[0050] A particle capture and manipulation assembly, including an illumination light source, a first dichroic mirror, a third lens, and a sample container. The illumination light source irradiates the sample container through the first dichroic mirror. The first dichroic mirror receives the astigmatic non-uniform partially coherent light beam and transmits the astigmatic non-uniform partially coherent light beam to the third lens. The third lens focuses the astigmatic non-uniform partially coherent light beam to capture and longitudinally manipulate particles in the sample container;

[0051] And a particle observation assembly, including a charge coupled device, which observes the process of particle capture and manipulation in the sample container.

[0052] In an embodiment of the present invention, the astigmatic non-uniform partially coherent light beam generating assembly further includes a first filter, a beam expander, and a beam splitter disposed between the helium-neon laser and the digital micromirror device.

[0053] The above technical solution of the present invention has the following advantages compared with the prior art:

[0054] The present invention effectively suppresses the problem of the distortion of the optical tweezer potential well caused by the coherent superposition of laser modes. Based on the special wavefront modulation mechanism of the astigmatic light beam, by introducing an asymmetric optical phase distribution, a stable double optical trap three-dimensional optical potential field is constructed in the optical axis direction. This potential field utilizes the synergistic effect of the optical gradient force and the scattering force to achieve multi-dimensional spatial capture and precise manipulation of micro-nano particles. The provided device adopts a compact single-beam astigmatic modulation architecture, and realizes the dynamic regulation of the astigmatic parameters of the light beam by optimizing the combination of cylindrical lenses. Experimental verification shows that the system has a sub-micron spatial resolution. Combining high-speed optoelectronic detection and real-time digital signal processing technology, it can achieve millisecond-level response and feedback control of the position information of micro-nano particles. Description of the Drawings

[0055] In order to make the content of the present invention easier to be clearly understood, the following further details the present invention according to the specific embodiments of the present invention and in combination with the drawings, where,

[0056] Figure 1 is a schematic flow chart of a method for longitudinal double optical trap particle manipulation based on astigmatic coherent engineering provided in the embodiment of the present invention;

[0057] Figure 2 is a schematic diagram of the process of strongly focusing and capturing particles provided in the embodiment of the present invention;

[0058] Figure 3 is a schematic structural diagram of a device for longitudinal double optical trap particle manipulation based on astigmatic coherent engineering provided in the embodiment of the present invention;

[0059] Figure 4In (a), it represents the axial light intensity evolution distribution of the Laguerre non-uniform partially coherent beam under different coherence lengths; (b) and (c) respectively represent the axial light intensity evolution distribution of the astigmatic non-uniform partially coherent (ANUC) beam under different coherence lengths and cross factors;

[0060] Figure 5 In (a), it represents the longitudinal gradient force distribution of the ANUC beam acting on two types of particles with different refractive indices ( ); (b) represents the scattering force distribution of the ANUC beam acting on two types of particles with different refractive indices ( ); (c1~c3) represent the transverse gradient force distribution of the ANUC beam acting on two types of particles with different refractive indices ( ), where (c1) represents the transverse gradient force distribution in the x direction, (c2) represents the transverse gradient force distribution in the y = x direction, and (c3) represents the transverse gradient force distribution in the y = -x direction;

[0061] Figure 6 In (a), it represents the longitudinal gradient force distribution of the ANUC beam acting on particles with a large refractive index ( ) under different coherence lengths; (b) represents the longitudinal gradient force distribution of the ANUC beam acting on particles with a large refractive index ( ) under different cross factors;

[0062] Figure 7 In (a), it represents the position change of the stable trapping position of the particles with the coherence length under different cross factors; (b) represents the position change of the stable trapping position of the particles with the cross factor under different coherence lengths;

[0063] Explanation of the reference numerals in the specification drawings: 1. Helium-neon laser; 2. First filter; 3. Beam expander; 4. Beam splitter; 5. Digital micromirror device; 6. First lens; 7. Single-hole filter; 8. Second lens; 9. Illumination light source; 10. First dichroic mirror; 11. Third lens; 12. Sample container; 13. Second dichroic mirror; 14. Fourth lens; 15. Fifth lens; 16. Charge-coupled device; 17. Host computer; 18. Grating generator. Detailed implementation manners

[0064] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the exemplified embodiments shall not be construed as limiting the present invention.

[0065] Embodiment 1:

[0066] As Figure 1As shown in the figure, the present invention provides a method and device for longitudinal dual optical trap particle manipulation based on astigmatic coherent engineering, and the method includes the following steps:

[0067] S1: Modulate the incident light field using a binary grating to generate an astigmatic non-uniform partially coherent light beam;

[0068] S2: Focus the astigmatic non-uniform partially coherent light beam, and change the optical radiation force generated by the interaction between the momentum carried by it and matter by regulating the light field distribution of the focused astigmatic non-uniform partially coherent light beam, so as to generate multiple optical potential wells near the geometric focus;

[0069] S3: The optical potential well captures and longitudinally manipulates the particles by regulating the correlation structure, and the capture and manipulation process is observed in real time through an imaging system.

[0070] Further, in S1, the method for generating an astigmatic non-uniform partially coherent light beam is as follows:

[0071] By analyzing the electric field component of the incident light field, the cross-spectral density function of the statistically stationary random scalar light beam in the spatial frequency domain is obtained:

[0072] (1)

[0073] Wherein, and represent the random electric field components in the vector field, and represent the arbitrary spatial position vectors on the cross-section of the light source, < > represents the ensemble average process, and * represents the complex conjugate operation;

[0074] Convert the formula (1) into a cross-spectral density function in the form of a superposition of integral kernels:

[0075] (2)

[0076] Wherein, represents an arbitrary integral kernel function, r represents the position vector on the cross-section of the light source, r includes and , represents the non-negative weight function of the integral kernel function, and the Fourier space parameter , is an arbitrary vector in the Fourier space;

[0077] In order to design an astigmatic non-uniform partially coherent (ANUC) light beam with longitudinal manipulation ability and excellent self-focusing characteristics, the integral kernel function is set to the Fourier transform form:

[0078] (3)

[0079] wherein, i is the imaginary unit, λ is the wavelength, is a function related to the position vector r, is proportional to and forms a proportional relationship, is a real constant, and the complex amplitude function , is the beam waist size of the light beam, which is characterized by a Gaussian statistical distribution related to the astigmatic phase .

[0080] The spectral coherence degree expression of the ANUC beam is obtained by normalizing the cross-spectral density function:

[0081] (4).

[0082] Here, the astigmatic phase is defined in the form of a cross-phase: , wherein is the cross coefficient, representing the intensity of the cross-phase, and x and y are the perpendicular components of the position vector r. The designed non-negative weight function has the following expression:

[0083] (5),

[0084] wherein, a is a positive real constant that determines the waist width of the weight function. Through these settings, the cross-spectral density function of the ANUC beam is simplified after integrating with respect to v to:

[0085] (6),

[0086] wherein, the spectral coherence degree of the ANUC beam is expressed as:

[0087] (7),

[0088] wherein, , ( r 1 s - r 2 s ) represents the difference in the r 1 and r 2 orders of any two points s in space, x 1 and y 1 are r 1Two orthogonal components of x 2 and y 2 are r 2 two orthogonal components of u represents the cross factor; the coherence length , which characterizes the coherence degree between different spatial positions within the light beam and determines the interference effect between photons. The wave number , if , is non - linear with respect to the position vector , the result is an astigmatic spatial correlation structure.

[0089] Based on the above - mentioned theoretical basis analysis, in order to generate an astigmatic non - uniform partially coherent light beam in actual operation, based on formula (2), the mode decomposition method is used to discretize the Fourier - space parameter v, obtaining a finite set of a series of uncorrelated and fully coherent modes, that is, the cross - spectral density of the astigmatic non - uniform partially coherent light beam:

[0090] (8),

[0091] where M is the number of discrete samples, m is the label of a single mode, is the unit interval after the discretization of the Fourier - space parameter v, represents the discrete pseudo - mode, corresponding to the mode weight value in the weight function .

[0092] The above formula (8) directly corresponds to sampling pseudo - modes at equal intervals within the interval of in actual operation. The number of samples is set to M, and M prepared binary gratings are loaded into a digital micromirror device (DMD). Each discrete corresponds to a pseudo - mode, determines its display probability, thereby realizing the modulation of the incident light field and generating an astigmatic non - uniform partially coherent light beam.

[0093] Furthermore, in S2, the method for generating multiple optical potential wells near the geometric focus is as follows:

[0094] Using the generalized Collins formula, the astigmatic non - uniform partially coherent light beam is transmitted from the input plane of the lens to the target plane at a distance z from it through the ABCD ray - transfer system. The cross - spectral density function at the target plane is expressed as:

[0095] (9),

[0096] The astigmatic inhomogeneous partially coherent beam is focused by a lens focusing system, and the transfer matrix of the lens focusing system is:

[0097] (10),

[0098] where A, B, C, and D are the transfer matrix elements, f is the focal length of the lens, and I is the unit light intensity. Substituting Equation (10) into Equation (9), when ρ1 = ρ2, the light intensity of the focused astigmatic inhomogeneous partially coherent beam is obtained as I (ρ, z) = W (ρ1, ρ2, z );

[0099] The beam can be conceptualized as a collection of a large number of photons. The momentum carried by the focused astigmatic inhomogeneous partially coherent beam generates optical radiation forces including scattering forces and gradient forces when interacting with matter, which will cause the particles to be pushed away or confined in an optical potential well; the scattering force and the gradient force are respectively expressed as:

[0100] (11),

[0101] (12),

[0102] where represents the scattering cross-section, represents the unit vector along the propagation direction, is the light intensity at the beam exit surface; γ represents the relative refractive index, , is the refractive index of the particle, is the refractive index of the surrounding ambient medium, represents the gradient of the light intensity at the beam exit surface, R is the particle radius, represents the speed of light in vacuum;

[0103] By regulating the light field distribution of the astigmatic inhomogeneous partially coherent beam, a force balance point is generated in the gradient force distribution, and the gradient force intensity at this force balance point is greater than the scattering force, thereby eliminating the negative impact of the scattering force on trapping. The particles near the geometric focus are confined to different specified positions in the light field, forming multiple optical potential wells longitudinally;

[0104] where G() represents the Green's function, , represents the transverse position vector at the target plane z, ρ1 and ρ2 represent any transverse position vectors at the target plane z, z is the beam propagation distance, is the beam wavelength, k is the beam wave number, and i is the imaginary unit.

[0105] As Figure 2 shown, the optical potential well captures and longitudinally manipulates microparticles by regulating the correlation structure.

[0106] In summary, the present invention calculates the scattering force and gradient force of an astigmatic inhomogeneous partially coherent beam on particles. The results show that this beam can be used to generate a double optical potential well longitudinally to effectively capture and manipulate large refractive index microparticles, and further manipulate the captured particles by regulating its correlation structure. At the same time, a stable double optical potential well state is maintained when the coherence is improved.

[0107] Embodiment 2:

[0108] Based on the same inventive concept as in Embodiment 1, as Figure 3 shown, the present invention also provides a device for longitudinal double optical trap microparticle manipulation based on astigmatic coherence engineering, which implements the method for longitudinal double optical trap microparticle manipulation described in Embodiment 1. The device includes: an astigmatic inhomogeneous partially coherent beam generation component, a microparticle capture and manipulation component, and a particle observation component;

[0109] Among them, the astigmatic inhomogeneous partially coherent beam generation component includes a helium-neon laser 1, a first filter 2, a beam expander 3, a beam splitter 4, a digital micromirror device 5, a grating generator 18, a first lens 6, a single-hole filter 7, and a second lens 8; preferably, the first filter 2 is a neutral density filter.

[0110] The first filter 2, the beam expander 3, the beam splitter 4, and the digital micromirror device 5 are arranged on the transmission path of the completely coherent laser beam with a wavelength of 632.8 nm emitted by the helium-neon laser 1. The first filter 2 is used to adjust the intensity of the completely coherent laser beam. The beam expander 3 expands the beam passing through the first filter 2 to increase its cross-sectional area; the beam splitter 4 divides the expanded beam into multiple beams, and the transmitted beam is transmitted to the digital micromirror device 5, and interacts with the binary grating generated by the grating generator 18 in the digital micromirror device 5 to obtain a modulated beam;

[0111] The first lens 6, the single-hole filter 7, and the second lens 8 that constitute a 4f filtering system are sequentially arranged on the transmission path of the modulated beam; the modulated beam first enters the first lens 6, and the parallel light collimated by the first lens 6 passes through the single-hole filter 7. The single-hole filter 7 selectively extracts the required +1 order diffraction beam, and finally is focused by the second lens 8 to generate an astigmatic inhomogeneous partially coherent beam on the focal plane of the second lens 8.

[0112] The particle capture and manipulation assembly includes an illumination light source 9, a first dichroic mirror 10, a third lens 11, and a sample container 12. The first dichroic mirror 10 receives the astigmatic non-uniform partially coherent beam, transmits the astigmatic non-uniform partially coherent beam to the third lens 11. The focal length of the third lens 11 is 10 mm, which focuses the astigmatic non-uniform partially coherent beam. The sample container 12 is located near the focal point of the focusing optical path of the third lens 11 and is used to place the particles to be captured and manipulated.

[0113] The illumination light source 9 irradiates the sample container 12 through the first dichroic mirror 10. The first dichroic mirror 10 receives the astigmatic non-uniform partially coherent beam, and the focused beam captures and longitudinally manipulates particles in the sample container 12.

[0114] The particle observation assembly includes a charge-coupled device 16 and a host computer 17. The host computer 17 is connected to the charge-coupled device 16, and the charge-coupled device 16 and the host computer 17 observe the process of particle capture and manipulation in the sample container 12.

[0115] First, a comparison was made Figure 4 between the focused Laguerre non-uniform partially coherent beam shown in (a) in Figure 4 and the astigmatic non-uniform partially coherent beams shown in (b) and (c) in Figure 4 where "Intensity" in (a)-(c) in

[0116] represents the light intensity. As the coherence increases, the focusing characteristics of the Laguerre non-uniform partially coherent beam gradually degenerate, changing from double self-focusing to single self-focusing, and the self-focusing intensity gradually increases. The astigmatic non-uniform partially coherent beam always maintains the stable beam characteristics of double self-focusing, and the self-focusing phenomenon becomes more significant with the increase of the coherence length and the cross factor. The increase of the coherence length leads to a gradual increase in the peak intensity, and the increase of the cross factor leads to the self-focusing position gradually moving away from the geometric focal position of the lens. Figure 5 According to formulas (11) and (12), the optical radiation force of the astigmatic non-uniform partially coherent beam on the particles is analyzed. As shown in (a) in Figure 5 there are three stable capture points P1, O, and P2 on the optical axis. Particles with a refractive index greater than the surrounding medium can be captured at points P1 and P2, and particles with a refractive index less than the surrounding medium can be captured at point O.

[0117] In addition, combined with Figure 5In (b), for the analysis of the scattering force acting on the particle, the astigmatic non-uniform partially coherent beam can form stable three-dimensional optical potential wells at two points P1 and P2 for stably trapping particles with a refractive index greater than that of the surrounding medium, and the influence of the scattering force on the trapping stability can be ignored.

[0118] Meanwhile, as shown in Figure 6 (a), Figure 6 (b), Figure 7 (a) and Figure 7 (b) of [reference], the particles can be longitudinally manipulated by regulating the coherence length and the cross factor. Meanwhile, as the coherence length increases, the dual optical potential well state is still maintained.

[0119] In summary, the present invention provides a method and device for generating an astigmatic non-uniform partially coherent beam that can still maintain longitudinal dual optical trap trapping and manipulation of particles under high coherence conditions, and studies the optical radiation force acting on Rayleigh particles, which has broad application prospects in the field of particle trapping and manipulation.

[0120] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for manipulating particles based on longitudinal dual optical traps of astigmatic coherent engineering, characterized in that, It includes the following steps: S1: Modulate the incident light field using a binary grating to generate an astigmatic non-uniform partially coherent beam; S2: Focus the astigmatic non-uniform partially coherent beam, and by regulating the light field distribution of the focused astigmatic non-uniform partially coherent beam, change the optical radiation force generated by the interaction between its carried momentum and matter, so as to generate multiple optical potential wells near the geometric focus; S3: The optical potential wells capture and longitudinally manipulate microparticles through regulating the correlation structure, and the capture and manipulation process is observed in real time through an imaging system.

2. The method for longitudinal dual optical trap particle manipulation based on astigmatic coherent engineering according to claim 1, wherein In S1, the method for generating an astigmatic non-uniform partially coherent beam is as follows: By analyzing the electric field component of the incident light field, obtain the cross-spectral density function of a statistically stationary random scalar beam in the spatial frequency domain: (1)， Among them, and represent the random electric field components in the vector field, and represent an arbitrary spatial position vector on the cross-section of the light source, < > represents the ensemble average process, and * represents the complex conjugate operation; Convert formula (1) into a cross-spectral density function in the superposition form of integral kernels: (2)， Among them, represents an arbitrary integral kernel function, r represents the position vector on the cross-section of the light source, and r includes and , represents the non-negative weight function of the integral kernel function, and the Fourier space parameter , is an arbitrary vector in the Fourier space; Discretize the Fourier space parameter v to obtain a finite set of a series of uncorrelated and fully coherent modes, that is, the cross-spectral density of the astigmatic non-uniform partially coherent beam: (3)， where M is the number of discrete samples, and m is the annotation of a single pattern among them. is the unit interval after discrete processing of the Fourier space parameter v. represents a discrete pseudo-pattern, corresponding to in the weight function the pattern weight value.

3. The method for longitudinal dual optical trap particle manipulation based on astigmatic coherent engineering according to claim 2, wherein The integral kernel function is as follows: (4)， wherein, i is the imaginary unit, λ is the wavelength, is a function related to the position vector r, is proportional to a proportional relationship, is a real constant, and the complex amplitude function , is the beam waist size of the light beam.

4. The method for longitudinal dual optical trap particle manipulation based on astigmatic coherent engineering according to claim 2, wherein The non - negative weight function is as follows: (5)， where a is a positive real constant determining the waist width of the weight function.

5. The method for longitudinal dual optical trap particle manipulation based on astigmatic coherent engineering according to claim 2, characterized in that, The spectral coherence degree of the astigmatic non-uniform partially coherent beam is as follows: (6)， Among them, , r is the position vector, ( r 1 s - r 2 s ) represents any two points in space r 1 and r 2 's s order difference, x 1 and y 1 are r 1 's two orthogonal components, x 2 and y 2 are r 2 's two orthogonal components; u represents the cross factor, represents the coherence length, a is a positive real constant that determines the waist width of the weight function, is a real constant, is the wave number, i is the imaginary unit.

6. The method for longitudinal dual optical trap particle manipulation based on astigmatic coherent engineering according to claim 2, wherein In S2, the method for generating multiple optical potential wells near the geometric focus is as follows: Transmit the astigmatic non-uniform partially coherent beam from the input plane of the lens to a target plane at a distance z from it, and the cross-spectral density function at the target plane is expressed as: (7)； Focus the astigmatic non-uniform partially coherent beam through a lens focusing system, and the transfer matrix of the lens focusing system is: (8)； Substitute Equation (8) into Equation (7). When ρ1 = ρ2, the intensity of the astigmatic partially coherent beam after focusing is obtained I (ρ,z)= W (ρ1,ρ2, z ); The momentum carried by the focused astigmatic non-uniform partially coherent beam generates an optical radiation force when interacting with matter, and the optical radiation force includes a scattering force and a gradient force; By regulating the light field distribution of the astigmatic non-uniform partially coherent beam, make the gradient force distribution generate a force balance point, and the gradient force intensity at this force balance point is greater than the scattering force. The particles near the geometric focus are restricted to different specified positions in the light field, and multiple optical potential wells are formed longitudinally; Among them, G() represents the Green's function, , A, B, C, D are the elements of the transfer matrix, f is the focal length of the lens, I is the unit light intensity, represents the transverse position vector at the target plane z, ρ1 and ρ2 represent any transverse position vectors at the target plane z, z is the beam propagation distance, is the beam wavelength, k is the beam wave number, and i is the imaginary unit.

7. The method for longitudinal dual optical trap particle manipulation based on astigmatic coherent engineering according to claim 6, wherein The scattering force is as follows: (9)， Among them, represents the scattering cross section, represents the unit vector along the propagation direction, is the refractive index of the surrounding environmental medium, is the light intensity at the light-emitting surface of the light beam, represents the speed of light in vacuum.

8. The method for longitudinal dual optical trap particle manipulation based on astigmatic coherent engineering according to claim 6, characterized in that, The gradient force is as follows: (10)， Among them, γ represents the relative refractive index, , is the refractive index of the particle, is the refractive index of the surrounding environmental medium, represents the gradient of the light intensity at the light beam exit surface, R is the particle radius, and represents the speed of light in vacuum.

9. An apparatus for manipulating particles based on longitudinal dual optical traps of astigmatic coherent engineering, characterized in that, Implement the method for longitudinal dual optical trap microparticle manipulation based on astigmatic coherent engineering as described in any one of claims 1 to 8. The device includes: An astigmatic non-uniform partially coherent beam generation component, including a helium-neon laser, a digital micromirror device, a grating generator, and a 4f filtering system; the digital micromirror device is arranged on the transmission path of the fully coherent laser beam emitted by the helium-neon laser, the binary grating generated by the grating generator is loaded on the digital micromirror device, the fully coherent laser beam and the binary grating interact to obtain a modulated beam, the 4f filtering system is arranged on the transmission path of the modulated beam, and the modulated beam generates an astigmatic non-uniform partially coherent beam through the 4f filtering system; A particle capture and manipulation assembly, including an illumination light source, a first dichroic mirror, a third lens, and a sample container. The illumination light source irradiates the sample container through the first dichroic mirror. The first dichroic mirror receives the astigmatic non-uniform partially coherent light beam and transmits the astigmatic non-uniform partially coherent light beam to the third lens. The third lens focuses the astigmatic non-uniform partially coherent light beam to capture and longitudinally manipulate particles in the sample container; and a particle observation assembly, including a charge-coupled device, which observes the process of particle capture and manipulation in the sample container.

10. The device for longitudinal dual optical trap particle manipulation based on astigmatic coherent engineering according to claim 9, wherein The astigmatic non-uniform partially coherent light beam generating assembly further includes a first filter, a beam expander, and a beam splitter disposed between the helium-neon laser and the digital micromirror device.

Images