Phase regulation and control method, device and system for potential well stiffness of holographic optical tweezers

Abstract

The invention discloses a phase regulation and control method, device and system for holographic optical tweezer potential well stiffness, and the method comprises the steps: calculating a decomposition matrix formula, a matrix expression and a Hermi matrix expression according to input system configuration parameters, carrying out the expansion of a stiffness coefficient of an optical trap through the Hermi matrix expression, and obtaining a stiffness coefficient expansion expression, performing phase optimization on the spatial light modulator based on a pixel symmetry rule to obtain an optimized phase value, generating a regulation and control instruction through the optimized phase value, sending the regulation and control instruction to the spatial light modulator, and recalculating a coefficient value of the stiffness coefficient expansion expression, and if the coefficient value or the number of optimization times meets the iterative optimization condition, returning to the step of performing phase optimization on the spatial light modulator. According to the phase regulation and control method, the Hermi matrix expression and the stiffness coefficient expansion expression can be solved according to the system configuration parameters, phase modulation is carried out on the light beam by generating the regulation and control instruction, and the application effect of independent optimization of the potential well stiffness phase is improved through phase iterative optimization.

Description

Technical Field

[0001] The present invention relates to the technical field of spatial light modulation, and in particular to a phase control method, device and system for the potential well stiffness of holographic optical tweezers. Background Art

[0002] Existing optical tweezers generally use ordinary Gaussian beams with diffraction limits to capture samples. For uniform spherical samples, when the sample radius is greater than the laser wavelength, the potential well stiffness of ordinary optical tweezers will decrease as the sample radius increases, and the change is approximately inversely proportional. Therefore, for samples with large diameters, the potential well stiffness of ordinary optical tweezers is small, and the capture is unstable. In order to improve the stability of the light beam in capturing the sample, the potential well stiffness can be optimized. The existing technical methods usually require the phase and light intensity to be optimized and modulated at the same time, and the implementation process is very complicated. If the phase of the potential well stiffness is optimized separately according to the existing technology, there is a problem of poor optimization effect. Therefore, the method of optimizing the potential well stiffness of optical tweezers in the existing technical method has the problem of high optimization complexity. Summary of the invention

[0003] The embodiments of the present invention provide a phase control method, device and system for the potential well stiffness of holographic optical tweezers, aiming to solve the problem of high optimization complexity in the method for optimizing the potential well stiffness of optical tweezers in the prior art.

[0004] In a first aspect, an embodiment of the present invention provides a phase control method for the stiffness of a holographic optical tweezers potential well, the method being applied to a controller, the controller being communicatively connected to a spatial light modulator in a phase control system, wherein the method comprises:

[0005] If the input system configuration parameters are received, plane wave decomposition is performed on the electric field of the light trap according to the system configuration parameters to obtain a corresponding decomposition matrix;

[0006] The decomposed matrix is ​​transformed according to a preset vector spherical harmonic function and a beam distribution of the spatial light modulator to obtain a corresponding matrix expression;

[0007] Calculate a Hermitian matrix expression corresponding to the matrix expression according to the beam distribution of the spatial light modulator;

[0008] Expanding the stiffness coefficient of the light trap according to the Hermitian matrix expression to obtain a corresponding stiffness coefficient expansion expression;

[0009] Optimizing the phase of the spatial light modulator according to the pixel symmetry rule, the Hermitian matrix expression and the preset phase limiting condition to obtain an optimized phase value;

[0010] Generate a corresponding control instruction according to the optimized phase value and send it to the spatial light modulator to perform phase control on the spatial light modulator;

[0011] Recalculate the coefficient values ​​of the stiffness coefficient expansion expression according to the beam distribution of the spatial light modulator after phase regulation;

[0012] If the coefficient value or the number of optimizations meets the preset iterative optimization conditions, the step of performing phase optimization on the spatial light modulator is returned to perform iterative phase optimization on the spatial light modulator.

[0013] In a second aspect, an embodiment of the present invention further provides a phase control device for holographic optical tweezers potential well stiffness, wherein the device is configured in a controller, and the controller is communicatively connected with a spatial light modulator in a phase control system, wherein the device is used to execute the phase control method for holographic optical tweezers potential well stiffness as described in the first aspect above, and the device comprises:

[0014] A decomposition unit, configured to perform plane wave decomposition on the electric field of the light trap according to the system configuration parameters if the input system configuration parameters are received, so as to obtain a corresponding decomposition matrix;

[0015] A transformation unit, used for transforming the decomposed matrix expression according to a preset vector spherical harmonic function and a beam distribution of the spatial light modulator to obtain a corresponding matrix expression;

[0016] A calculation unit, configured to calculate a Hermitian matrix expression corresponding to the matrix expression according to the beam distribution of the spatial light modulator;

[0017] An expansion unit, used for expanding the stiffness coefficient of the light trap according to the Hermitian matrix expression to obtain a corresponding stiffness coefficient expansion expression;

[0018] A phase optimization unit, used for performing phase optimization on the spatial light modulator according to the pixel symmetry rule, the Hermitian matrix expression and the preset phase limiting condition to obtain an optimized phase value;

[0019] A control instruction sending unit, used for generating a corresponding control instruction according to the optimized phase value and sending the control instruction to the spatial light modulator to perform phase control on the spatial light modulator;

[0020] A coefficient value calculation unit, used for recalculating the coefficient value of the stiffness coefficient expansion expression according to the beam distribution of the spatial light modulator after phase control;

[0021] The return execution unit is used to return to the step of performing phase optimization on the spatial light modulator if the coefficient value or the number of optimization times meets the preset iterative optimization condition, so as to perform iterative phase optimization on the spatial light modulator.

[0022] In a third aspect, an embodiment of the present invention further provides a phase control system for the potential well stiffness of a holographic optical tweezers, wherein the system includes a controller, a laser, a beam expander, a half-wave plate, a polarization fractional cubic mirror, a spatial light modulator, an objective lens, and a camera;

[0023] The laser is used to emit a laser beam, the beam expander is arranged downstream of the laser, the polarization fractional cube is arranged downstream of the beam expander, and the half-wave plate is arranged between the polarization fractional cube and the beam expander;

[0024] The spatial light modulator is arranged downstream of the polarization fractional cube mirror, the dichroic mirror is arranged downstream of the spatial light modulator, and the objective lens and the camera are arranged on both sides of the dichroic mirror respectively;

[0025] The controller is in communication connection with the spatial light modulator, and the controller includes a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus;

[0026] Memory, used to store computer programs;

[0027] When the processor executes the computer program stored in the memory, the steps of the phase control method of the holographic optical tweezers potential well stiffness as described in the first aspect above are implemented.

[0028] In a fourth aspect, an embodiment of the present invention further provides a computer-readable storage medium having a computer program stored thereon, wherein when the computer program is executed by a processor, the steps of the method for phase control of the holographic optical tweezers potential well stiffness as described in the first aspect above are implemented.

[0029] The embodiment of the present invention provides a phase control method, device and system for the stiffness of a holographic optical tweezers potential well. The method includes: calculating a decomposition matrix, a matrix expression and a Hermitian matrix expression according to input system configuration parameters, expanding the stiffness coefficient of the optical well through the Hermitian matrix expression to obtain a stiffness coefficient expansion expression, optimizing the phase of the spatial light modulator based on the pixel symmetry rule to obtain an optimized phase value, generating a control instruction through the optimized phase value and sending it to the spatial light modulator and recalculating the coefficient value of the stiffness coefficient expansion expression, and returning to execute the step of optimizing the phase of the spatial light modulator if the coefficient value or the number of optimizations meets the iterative optimization condition. The above-mentioned phase control method for the stiffness of the optical tweezers potential well can solve the Hermitian matrix expression and the stiffness coefficient expansion expression according to the system configuration parameters, phase modulate the light beam by generating a control instruction, and maximize the coefficient value of the stiffness coefficient through phase iterative optimization, thereby improving the application effect of the phase of the potential well stiffness being optimized separately. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0031] Figure 1 A method flow chart of a phase control method of a holographic optical tweezers potential well stiffness provided by an embodiment of the present invention;

[0032] Figure 2 A structural diagram of a phase control system for the potential well stiffness of holographic optical tweezers provided in an embodiment of the present invention;

[0033] Figure 3 A schematic block diagram of a phase control device for holographic optical tweezers potential well stiffness provided by an embodiment of the present invention;

[0034] Figure 4 It is a schematic block diagram of a computer device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0037] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0038] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0039] See also Figure 1 As shown in the figure, the embodiment of the present invention provides a phase control method for the stiffness of the potential well of holographic optical tweezers. The method is applied in a controller. The method is executed by an application installed in the controller. The controller can be a laptop, desktop computer, tablet computer or mobile phone. The controller can also be a control board that realizes data processing and instruction generation, such as a PLC (Programmable Logic Controller) circuit board carrying an MCU chip. Figure 2 As shown, the controller is connected to the spatial light modulator in the phase control system for communication. The controller can obtain the system configuration parameters input by the user and the beam distribution of the spatial light modulator. The controller can also send corresponding control instructions to the spatial light modulator to perform phase control on the spatial light modulator. Figure 1 As shown, the method includes steps S110 to S180.

[0040] S110 , if the input system configuration parameters are received, plane wave decomposition is performed on the electric field of the light trap according to the system configuration parameters to obtain a corresponding decomposition matrix.

[0041] If the input system configuration parameters are received, the electric field of the light trap is plane-wave decomposed according to the system configuration parameters to obtain the corresponding decomposition matrix. The system configuration parameters include imaging resolution, focal length, and pixel size. The imaging resolution is the resolution of the image acquired by the camera. The imaging resolution can be used to reflect the fineness of the imaging. The higher the imaging resolution, the finer the image obtained. The focal length is the focal length of the objective lens, and the unit of the focal length is mm (millimeter). The pixel size is the size of the pixel in the spatial light modulator.

[0042] The phase control system of the holographic optical tweezers potential well stiffness modulates the light beam through a spatial light modulator, and uses a high numerical aperture objective lens to form a tightly focused light beam as a light trap to capture the sample. The stiffness coefficient κ of the light trap can be expressed as formula (1) through a matrix quadratic form;

[0043]

[0044] Among them, A is a set of electric field vectors of the light trap under the basis, that is, A is the Hermitian matrix describing the interaction between electric field and matter. j is the jth group of vectors in A, is the transposed matrix of vector A. In order to calculate κ specifically, the matrix and vector A are expressed in a set of bases; for the implementation of the above method, plane waves are selected as the basis, and the calculation results can be easily applied. is a Hermitian matrix with κ≤λ max |A| 2 , where λ max For the matrix The largest eigenvalue is when and only when A is λ max The equality sign holds true for the corresponding eigenvector. But in general, it is impossible to modulate Gaussian light into the electric field expressed by the corresponding eigenvector through pure phase modulation. Therefore, the technical method of this application introduces iterative calculation to iteratively optimize the phase. In view of the characteristics of independent control of single pixels of spatial light modulators, the technical method of this application also designs a set of fast-converging iterative methods, and combines the pixel symmetry rules according to actual application needs during the iteration process.

[0045] In a specific embodiment, step S110 includes sub-steps: determining the center coordinates of each pixel in the spatial light modulator according to the imaging resolution and pixel size in the system configuration parameters; determining the basis of plane wave decomposition by the focal length and the center coordinates in the system configuration parameters; performing plane wave decomposition on the electric field vector of the light trap according to the basis of the plane wave decomposition to obtain a corresponding decomposition matrix.

[0046] Specifically, the imaging resolution in the system configuration parameters is 2M×2N, and the pixel size is s. The center coordinates (x m ,y n ) is expressed using formula (2):

[0047]

[0048] According to the focal length in the system parameters and the center coordinates of the pixel point, the relationship between the coordinates (x, y) on the spatial light modulator and the focal length can be determined as shown in formula (3).

[0049]

[0050] Where f is the focal length, k is the wave number, k = (2π) / λ, λ is the wavelength, and π is the circumference. Since the spatial light modulator plane is equivalent to the back focal plane of the objective lens imaging, the plane wave decomposition can be conveniently used to convert A j The phase mapping is the phase of the corresponding pixel point on the spatial light modulator. For a single-frequency laser, the basis expression of the plane wave decomposition can be further determined as shown in formula (4):

[0051]

[0052] Among them, k x , k y and k z k is the wave number corresponding to the three-dimensional coordinate value of the pixel point on the spatial light modulator in the x direction, y direction, and z direction, respectively. x , k y and k z Relationship satisfaction For laser propagation along the z direction, e is the base of natural logarithm, is a unit vector, and i is the imaginary part of a complex number.

[0053] Based on the above plane wave decomposition basis, the electric field vector A of the light trap can be decomposed by plane wave. Based on the plane wave decomposition, a one-to-one correspondence is established with each pixel on the spatial light modulator based on formula (3). Based on this plane wave decomposition basis, the momentum in the x direction can be expressed by a matrix quadratic form as formula (5):

[0054]

[0055] Among them, p x represents the momentum of the electric field vector A in the x direction, is Planck's constant, is a diagonal matrix, which can be expressed using formula (6):

[0056]

[0057] Among them, p and q are the coordinate subscript values, δ mp is the phase corresponding to m and p, δ nq is the phase corresponding to n and q.

[0058] S120, transforming the decomposed matrix expression according to the preset vector spherical harmonic function and the beam distribution of the spatial light modulator to obtain a corresponding matrix expression.

[0059] The decomposition matrix is ​​transformed according to the preset vector spherical harmonic function and the beam distribution of the spatial light modulator to obtain the corresponding matrix expression. Further, the beam distribution of the spatial light modulator can be obtained, and the decomposition matrix is ​​transformed according to the beam distribution and the vector spherical harmonic function to obtain the matrix expression under plane wave decomposition.

[0060] In a specific embodiment, step S120 includes sub-steps: solving the sample scattered electric field of the beam distribution according to the vector spherical harmonic function to obtain a linear transformation matrix; transforming the decomposed matrix according to the linear transformation matrix to obtain a corresponding matrix expression.

[0061] For general scattering problems, the sample scattered electric field B of the beam distribution can be expressed as a linear transformation of the electric field vector A, using formula (7):

[0062]

[0063] in, is the linear transformation matrix obtained by solving the sample scattering electric field B of the uniform spherical sample under the beam distribution under the vector spherical harmonic decomposition. The linear transformation matrix obtained by solving the sample scattering electric field B of the uniform spherical sample under the vector spherical harmonic decomposition is Matrix, which is based on the classical Mie scattering solution.

[0064] Based on the linear transformation matrix obtained above, the decomposed matrix is ​​transformed; in the optical tweezers system, the incident light is symmetrical about the propagation direction, so the momentum along any direction of the cross section is 0, then the force F x The magnitude is proportional to the momentum of the scattered light Based on formula (7), formula (5) is transformed to obtain the corresponding matrix expression as shown in formula (8).

[0065]

[0066] The resulting formula (8) is also a matrix expression. for The replacement symbol for this expression. For vector The transpose of .

[0067] S130. Calculate a Hermitian matrix expression corresponding to the matrix expression according to the beam distribution of the spatial light modulator.

[0068] The Hermitian matrix expression corresponding to the matrix expression is calculated according to the beam distribution of the spatial light modulator. The phase shift of the sample in the plane wave can be obtained based on the beam distribution of the sample in the spatial light modulator, and the corresponding Hermitian matrix expression can be calculated based on the phase shift combined with the matrix expression.

[0069] In a specific embodiment, step S130 includes sub-steps: calculating a component calculation formula corresponding to the matrix expression according to the beam distribution of the spatial light modulator; comparing the stiffness coefficient of the light trap according to the component calculation formula and the matrix expression to obtain a corresponding Hermitian matrix expression.

[0070] In a specific embodiment, the component calculation formula corresponding to the matrix expression is calculated according to the beam distribution of the spatial light modulator, including: determining the phase offset of the plane wave according to the beam distribution; performing an offset superposition operation on the matrix expression according to the phase offset to obtain the corresponding component calculation formula.

[0071] First, the phase shift of the plane wave can be determined based on the beam distribution of the sample. For plane waves, additional phase Based on the limit offset, the matrix expression is offset and superimposed, that is, the components of the electric field vector A are expressed in terms of amplitude and phase as formula (9).

[0072]

[0073] where φ m,n is the phase of the spatial light modulator corresponding to the pixel loading modulation, and formula (9) is also the component calculation formula.

[0074] In a specific embodiment, the stiffness coefficient of the light trap is compared according to the component calculation formula and the matrix expression to obtain a corresponding Hermitian matrix expression, including: expanding the matrix expression according to the component calculation formula to obtain a corresponding expanded expression; superimposing the expanded expression according to the pixel origin vibration of the plane wave corresponding to the light beam distribution to obtain a first-order expanded calculation formula for the force of the stiffness coefficient of the light trap near the origin; comparing and superimposing the first-order expanded calculation formula for the force of the stiffness coefficient near the origin with the initial calculation formula of the stiffness coefficient to obtain a corresponding Hermitian matrix expression.

[0075] By expanding the matrix expression according to the obtained component calculation formula, the expanded expression shown in formula (10) can be obtained.

[0076]

[0077] For small vibrations of the sample near the origin, a superposition calculation can be performed based on the expanded expression to obtain the first-order expanded calculation formula of the corresponding stiffness coefficient κ near the origin as shown in formula (11).

[0078]

[0079] The obtained first-order expansion formula of the stiffness coefficient near the origin is compared and superimposed with formula (1), and the Hermitian matrix expression can be obtained as shown in formula (12):

[0080]

[0081] S140, expanding the stiffness coefficient of the light trap according to the Hermitian matrix expression to obtain a corresponding stiffness coefficient expansion expression.

[0082] The stiffness coefficient of the light trap is expanded according to the Hermitian matrix expression to obtain the corresponding stiffness coefficient expansion expression. Further, the stiffness coefficient of the light trap is expanded according to the Hermitian matrix expression to obtain the stiffness coefficient expansion expression shown in formula (13):

[0083]

[0084] S150, performing phase optimization on the spatial light modulator according to the pixel symmetry rule, the Hermitian matrix expression and the preset phase limiting condition to obtain an optimized phase value.

[0085] The phase of the spatial light modulator is optimized according to the pixel symmetry rule, the Hermitian matrix expression and the preset phase limiting condition to obtain the optimized phase value.

[0086] The phase of the spatial light modulator is optimized according to the pixel symmetry rule, the Hermitian matrix expression and the phase limit condition. Each time the optimization is performed, the phase value corresponding to a set of pixels (p, q) can be obtained again. Among them, for each individual pixel (p, q), it is assumed that the phases of other pixels are known. In order to maximize the coefficient value of formula (13), its phase should satisfy the corresponding phase restriction condition. The phase optimization formula in the phase restriction condition can be expressed by formula (14):

[0087]

[0088] In a specific embodiment, step S150 includes sub-steps: randomly assigning an initial phase to each pixel on the spatial light modulator; calculating an extended expression of a diagonal matrix corresponding to a vector spherical harmonic function according to the pixel symmetry rule; expanding the Hermitian matrix expression and the phase optimization formula in the phase limitation condition according to the extended expression to obtain corresponding coefficient expansion expressions and phase optimization expansion formulas; performing phase optimization on the initial phase according to the coefficient expansion expression and the phase optimization expansion formula to obtain an optimized phase value.

[0089] Specifically, during the first iterative optimization process, each individual pixel (p, q) on the spatial light modulator is first randomly assigned an initial phase (Subsequent iterative optimization steps do not require the initial phase to be assigned again Instead, it is optimized again based on the phase value obtained in the previous iterative optimization).

[0090] Furthermore, the extended expression of the diagonal matrix corresponding to the vector spherical harmonic function is calculated according to the pixel symmetry rule:

[0091] Due to the symmetry of the spatial light modulator pixels, k can be obtained according to this pixel symmetry rule. y,q =k x,q =k q ; According to this pixel symmetry rule, the diagonal matrix shown in formula (6) is expanded to obtain the y-direction expression corresponding to formula (6) as shown in formula (15):

[0092]

[0093] According to the extended expression, the Hermitian matrix expression and the phase optimization formula in the phase restriction condition are respectively expanded, and the Hermitian matrix expression corresponding to formula (12) is expanded, and the coefficient expansion expression obtained is shown in formula (16):

[0094]

[0095] The phase optimization formula (single-pixel optimal phase expression) corresponding to formula (14) is expanded, and the obtained phase optimization expansion formula is shown in formula (17):

[0096]

[0097] The intensity distribution of the incident light is centrally symmetric along the cross section, so A m,n =A n,m ; In order to keep formula (14) and formula (17) matching, it is necessary to limit φ m,n =φ n,mAt the same time, in order to keep the momentum of the incident light equal to 0, it is necessary to limit φ m,n =φ -m+1,-n+1 Under the above-mentioned limited conditions, the corresponding optimized phase value can be calculated based on formula (17). Iterative phase optimization based on the above-mentioned pixel symmetry rule can greatly reduce the amount of calculation.

[0098] S160, generating a corresponding control instruction according to the optimized phase value and sending the control instruction to the spatial light modulator to perform phase control on the spatial light modulator.

[0099] Generate a corresponding control instruction according to the optimized phase value and send it to the spatial light modulator to perform phase control on the spatial light modulator. The optimized phase of each pixel can be obtained through the above steps. After obtaining the optimized phase value, a corresponding control instruction is generated based on the optimized phase value and sent to the spatial light modulator. Specifically, a corresponding grayscale image can be obtained based on the optimized phase value, and a control instruction is generated based on the grayscale image and sent to the spatial light modulator. After receiving the control instruction, the spatial light modulator loads the grayscale image set in the control instruction, that is, phase control is performed on the spatial light modulator. By loading the grayscale image corresponding to the optimized phase value in the spatial light modulator, the optimization of the light trap stiffness coefficient of a specific sample can be achieved.

[0100] S170, recalculating the coefficient values ​​of the stiffness coefficient expansion expression according to the light beam distribution of the spatial light modulator after phase control.

[0101] The coefficient values ​​of the stiffness coefficient expansion expression are recalculated according to the beam distribution of the spatial light modulator after phase control. After phase control, the above stiffness coefficient expansion expression can be recalculated according to the beam distribution of the spatial light modulator, and the actual values ​​obtained are input into formula (16) to calculate the coefficient values ​​of the stiffness coefficient expansion expression.

[0102] S180. If the coefficient value or the number of optimizations meets a preset iterative optimization condition, return to the step of performing phase optimization on the spatial light modulator to perform iterative phase optimization on the spatial light modulator.

[0103] If the coefficient value or the number of optimizations meets the preset iterative optimization conditions, return to step S150 to perform iterative phase optimization on the spatial light modulator. Further, determine whether the coefficient value currently calculated meets the iterative optimization conditions, and at the same time determine whether the number of optimizations meets the iterative optimization conditions. Among them, it can be determined whether the coefficient value currently calculated is increased compared to the coefficient value before optimization. If it is increased, it is determined that the iterative optimization conditions are met; otherwise, it is determined that the iterative optimization conditions are not met. The number of optimizations is the number of times the spatial light modulator is phase optimized through the above steps. It can be determined whether the number of optimizations is greater than the number threshold set in the iterative optimization conditions. If the number of optimizations is greater than the number threshold, it is determined that the iterative optimization conditions are met; otherwise, it is determined that the iterative optimization conditions are not met.

[0104] If the coefficient value or the number of optimizations meets the iterative optimization condition, the phase optimization of the spatial light modulator continues, that is, returning to step S150. At this time, the currently used phase value is used as the initial phase for iterative optimization, that is, except for the first iterative optimization, the initial phase needs to be randomly assigned, and the subsequent iterative optimization does not need to randomly assign the initial phase again.

[0105] If the coefficient value and the number of optimization times do not meet the iterative optimization conditions, the above iterative optimization process is terminated, and the currently obtained phase value is used as the optimal phase value obtained by the final optimization.

[0106] In the phase control method of the potential well stiffness of holographic optical tweezers disclosed in the above embodiment, the method includes: calculating the decomposition matrix, matrix expression and Hermitian matrix expression according to the input system configuration parameters, expanding the stiffness coefficient of the optical trap through the Hermitian matrix expression to obtain the stiffness coefficient expansion expression, optimizing the phase of the spatial light modulator based on the pixel symmetry rule to obtain the optimized phase value, generating a control instruction through the optimized phase value and sending it to the spatial light modulator and recalculating the coefficient value of the stiffness coefficient expansion expression, if the coefficient value or the number of optimizations meets the iterative optimization condition, returning to execute the step of performing phase optimization on the spatial light modulator. The above phase control method of the potential well stiffness of optical tweezers can solve the Hermitian matrix expression and the stiffness coefficient expansion expression according to the system configuration parameters, phase modulate the light beam by generating a control instruction, and maximize the coefficient value of the stiffness coefficient through phase iterative optimization, thereby improving the application effect of the phase of the potential well stiffness being optimized separately.

[0107] The embodiment of the present invention also provides a phase control device for holographic optical tweezers potential well stiffness, which can be configured in a controller, and the controller is connected to the spatial light modulator in the phase control system for communication, and the phase control device for holographic optical tweezers potential well stiffness is used to execute any embodiment of the aforementioned phase control method for holographic optical tweezers potential well stiffness. Specifically, please refer to Figure 3, Figure 3 A schematic block diagram of a phase control device for holographic optical tweezers potential well stiffness provided in an embodiment of the present invention.

[0108] like Figure 3 As shown, the phase control device 100 of the holographic optical tweezers potential well stiffness includes a decomposition unit 110, a transformation unit 120, a calculation unit 130, an expansion unit 140, a phase optimization unit 150, a control instruction sending unit 160, a coefficient value calculation unit 170 and a return execution unit 180.

[0109] The decomposition unit 110 is used to perform plane wave decomposition on the electric field of the light trap according to the system configuration parameters if the input system configuration parameters are received, so as to obtain a corresponding decomposition matrix.

[0110] The transformation unit 120 is used to transform the decomposed matrix expression according to the preset vector spherical harmonic function and the beam distribution of the spatial light modulator to obtain a corresponding matrix expression.

[0111] The calculation unit 130 is used to calculate the Hermitian matrix expression corresponding to the matrix expression according to the beam distribution of the spatial light modulator.

[0112] The expansion unit 140 is used to expand the stiffness coefficient of the light trap according to the Hermitian matrix expression to obtain a corresponding stiffness coefficient expansion expression.

[0113] The phase optimization unit 150 is used to perform phase optimization on the spatial light modulator according to the pixel symmetry rule, the Hermitian matrix expression and the preset phase limiting condition to obtain an optimized phase value.

[0114] The control instruction sending unit 160 is used to generate a corresponding control instruction according to the optimized phase value and send it to the spatial light modulator to perform phase control on the spatial light modulator.

[0115] The coefficient value calculation unit 170 is used to recalculate the coefficient value of the stiffness coefficient expansion expression according to the light beam distribution of the spatial light modulator after phase control.

[0116] Return to the execution unit 180, which is used to return to the step of performing phase optimization on the spatial light modulator if the coefficient value or the number of optimization times meets the preset iterative optimization condition, so as to perform iterative phase optimization on the spatial light modulator.

[0117] The phase control device of the holographic optical tweezers potential well stiffness provided in the embodiment of the present invention applies the above-mentioned phase control method of the holographic optical tweezers potential well stiffness, calculates the decomposition matrix, matrix expression and Hermitian matrix expression according to the input system configuration parameters, expands the stiffness coefficient of the optical trap through the Hermitian matrix expression to obtain the stiffness coefficient expansion expression, optimizes the phase of the spatial light modulator based on the pixel symmetry rule to obtain the optimized phase value, generates a control instruction through the optimized phase value and sends it to the spatial light modulator and recalculates the coefficient value of the stiffness coefficient expansion expression, and returns to execute the step of performing phase optimization on the spatial light modulator if the coefficient value or the number of optimizations meets the iterative optimization condition. The above-mentioned phase control method of the optical tweezers potential well stiffness can solve the Hermitian matrix expression and the stiffness coefficient expansion expression according to the system configuration parameters, phase modulates the light beam by generating a control instruction, and maximizes the coefficient value of the stiffness coefficient through phase iterative optimization, thereby improving the application effect of the phase of the potential well stiffness being optimized separately.

[0118] The present application also provides a phase control system for the potential well stiffness of holographic optical tweezers, such as Figure 2 As shown, the system includes a controller 1, a laser 2, a beam expander 3, a half-wave plate 4, a polarization fractional cube 5, a spatial light modulator 6, an objective lens 7 and a camera 8; the laser 2 is used to emit a laser beam, the beam expander 3 is arranged downstream of the laser 2, the polarization fractional cube 5 is arranged downstream of the beam expander 3, and the half-wave plate 4 is arranged between the polarization fractional cube 5 and the beam expander 3; the spatial light modulator 6 is arranged downstream of the polarization fractional cube 5, the dichroic mirror 9 is arranged downstream of the spatial light modulator 6, the objective lens 7 and the camera 8 are respectively arranged on both sides of the dichroic mirror 9, and the controller 1 is connected to the spatial light modulator 6 for communication. The light beam is emitted by the laser 2, passes through the beam expander 3 for beam expansion, passes through the half-wave plate 4 for filtering, and then enters the polarization fractional cube 5 to obtain a polarized light beam. The polarization fractional cubic mirror 5 illuminates the spatial light modulator 6, and the spatial light modulator 6 adjusts the light beam reflected by the spatial light modulator 6 to the dichroic mirror 9 by performing phase control. The dichroic mirror 9 refracts the light beam reflected by the spatial light modulator 6 and emits it to the objective lens 7. The objective lens 7 illuminates the sample to obtain a reflected light beam. The reflected light beam passes through the dichroic mirror 9 and is collected by the camera 8, and the image of the sample can be obtained by the camera. In the process of imaging the sample, the controller 1 can output a control instruction to the spatial light modulator 6 to adjust the phase of the light beam reflected by the spatial light modulator 6 to the dichroic mirror 9.

[0119] The phase control device of the holographic optical tweezers potential well stiffness can be implemented in the form of a computer program. The computer program can be used in Figure 4 Runs on the computer device shown.

[0120] See also Figure 4 , Figure 4 is a schematic block diagram of a computer device provided by an embodiment of the present invention. The computer device may be a controller for executing a phase control method of a holographic optical tweezers potential well stiffness to perform spatial light phase control.

[0121] See also Figure 4 The computer device 500 includes a processor 502 , a memory and a communication interface 505 connected via a communication bus 501 , wherein the memory may include a storage medium 503 and an internal memory 504 .

[0122] The storage medium 503 can store an operating system 5031 and a computer program 5032. When the computer program 5032 is executed, the processor 502 can execute a phase control method for holographic optical tweezers potential well stiffness, wherein the storage medium 503 can be a volatile storage medium or a non-volatile storage medium.

[0123] The processor 502 is used to provide computing and control capabilities to support the operation of the entire computer device 500 .

[0124] The internal memory 504 provides an environment for the operation of the computer program 5032 in the storage medium 503. When the computer program 5032 is executed by the processor 502, the processor 502 can execute the phase control method of the holographic optical tweezers potential well stiffness.

[0125] The communication interface 505 is used for network communication, such as providing data information transmission, etc. Those skilled in the art will appreciate that Figure 4 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present invention, and does not constitute a limitation on the computer device 500 to which the solution of the present invention is applied. The specific computer device 500 may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0126] The processor 502 is used to run a computer program 5032 stored in the memory to implement the corresponding functions in the above-mentioned phase control method of the potential well stiffness of the holographic optical tweezers.

[0127] Those skilled in the art will understand that Figure 4 The embodiments of the computer device shown in the figure do not constitute a limitation on the specific composition of the computer device. In other embodiments, the computer device may include more or fewer components than shown in the figure, or combine certain components, or arrange the components differently. For example, in some embodiments, the computer device may only include a memory and a processor. In such embodiments, the structure and function of the memory and the processor are the same as those of the embodiment of the present invention. Figure 4 The embodiments shown are consistent and will not be described again here.

[0128] It should be understood that in the embodiment of the present invention, the processor 502 may be a central processing unit (CPU), and the processor 502 may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. Among them, the general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0129] In another embodiment of the present invention, a computer-readable storage medium is provided. The computer-readable storage medium may be a volatile or non-volatile computer-readable storage medium. The computer-readable storage medium stores a computer program, wherein when the computer program is executed by a processor, the steps included in the above-mentioned phase control method of the holographic optical tweezers potential well stiffness are implemented.

[0130] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the specific working process of the above-described equipment, devices and units can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here. Those of ordinary skill in the art can appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented with electronic hardware, computer software or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to the function. Whether these functions are executed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0131] In the several embodiments provided by the present invention, it should be understood that the disclosed equipment, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. Units with the same function may also be combined into one unit. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interfaces, devices or units, or may be an electrical, mechanical or other form of connection.

[0132] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the embodiments of the present invention.

[0133] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0134] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a computer-readable storage medium, including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned computer-readable storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a magnetic disk or an optical disk.

[0135] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A phase control method for the stiffness of a holographic optical tweezers potential well, characterized in that: The method is applied to a controller, the controller is communicatively connected with a spatial light modulator in a phase control system, and the method comprises: If the input system configuration parameters are received, plane wave decomposition is performed on the electric field of the light trap according to the system configuration parameters to obtain a corresponding decomposition matrix; The decomposed matrix is ​​transformed according to a preset vector spherical harmonic function and a beam distribution of the spatial light modulator to obtain a corresponding matrix expression; Calculate a Hermitian matrix expression corresponding to the matrix expression according to the beam distribution of the spatial light modulator; Expanding the stiffness coefficient of the light trap according to the Hermitian matrix expression to obtain a corresponding stiffness coefficient expansion expression; Optimizing the phase of the spatial light modulator according to the pixel symmetry rule, the Hermitian matrix expression and the preset phase limiting condition to obtain an optimized phase value; Generate a corresponding control instruction according to the optimized phase value and send it to the spatial light modulator to perform phase control on the spatial light modulator; Recalculate the coefficient value of the stiffness coefficient expansion expression according to the beam distribution of the spatial light modulator after phase regulation; If the coefficient value or the number of optimizations meets the preset iterative optimization conditions, the step of performing phase optimization on the spatial light modulator is returned to perform iterative phase optimization on the spatial light modulator.

2. The phase control method of the holographic optical tweezers potential well stiffness according to claim 1, characterized in that: The performing plane wave decomposition on the electric field of the light trap according to the system configuration parameters to obtain a corresponding decomposition matrix includes: Determine the center coordinates of each pixel in the spatial light modulator according to the imaging resolution and pixel size in the system configuration parameters; The focal length in the system configuration parameters and the center coordinates determine the basis of plane wave decomposition; The electric field vector of the light trap is subjected to plane wave decomposition according to the basis of the plane wave decomposition to obtain a corresponding decomposition matrix.

3. The phase control method of the holographic optical tweezers potential well stiffness according to claim 1, characterized in that: The method of transforming the decomposed matrix expression according to the preset vector spherical harmonic function and the beam distribution of the spatial light modulator to obtain a corresponding matrix expression also includes: Solving the sample scattered electric field of the beam distribution according to the vector spherical harmonic function to obtain a linear transformation matrix; The decomposed matrix expression is transformed according to the linear transformation matrix to obtain a corresponding matrix expression.

4. The phase control method of the holographic optical tweezers potential well stiffness according to claim 1, characterized in that: The step of calculating the Hermitian matrix expression corresponding to the matrix expression according to the beam distribution of the spatial light modulator comprises: Calculate a component calculation formula corresponding to the matrix expression according to the beam distribution of the spatial light modulator; The stiffness coefficient of the light trap is compared according to the component calculation formula and the matrix expression to obtain a corresponding Hermitian matrix expression.

5. The phase control method of the holographic optical tweezers potential well stiffness according to claim 4, characterized in that: The component calculation formula corresponding to the matrix expression is calculated according to the beam distribution of the spatial light modulator, including: determining a phase shift of a plane wave based on the beam profile; The matrix expression is subjected to an offset superposition operation according to the phase offset to obtain a corresponding component calculation formula.

6. The phase control method of the holographic optical tweezers potential well stiffness according to claim 4, characterized in that: The stiffness coefficient of the light trap is compared according to the component calculation formula and the matrix expression to obtain the corresponding Hermitian matrix expression, including: Expand the matrix expression according to the component calculation formula to obtain a corresponding expanded expression; The expansion expression is superimposed and calculated according to the pixel origin vibration of the plane wave corresponding to the beam distribution, so as to obtain a first-order expansion calculation formula of the force of the light trap stiffness coefficient near the origin; The first-order expansion calculation formula of the force of the stiffness coefficient near the origin is compared and superimposed with the initial calculation formula of the stiffness coefficient to obtain the corresponding Hermitian matrix expression.

7. The phase control method of the holographic optical tweezers potential well stiffness according to claim 1, characterized in that: The phase optimization of the spatial light modulator is performed according to the pixel symmetry rule, the Hermitian matrix expression and the preset phase limiting condition to obtain the optimized phase value, including: Randomly assigning an initial phase to each pixel on the spatial light modulator; Calculate the extended expression of the diagonal matrix corresponding to the vector spherical harmonic function according to the pixel symmetry rule; According to the extended expression, the Hermitian matrix expression and the phase optimization formula in the phase restriction condition are respectively expanded to obtain corresponding coefficient expansion expressions and phase optimization expansion formulas; The initial phase is optimized according to the coefficient expansion expression and the phase optimization expansion formula to obtain an optimized phase value.

8. A phase control device for holographic optical tweezers potential well stiffness, characterized in that: The device is configured in a controller, the controller is communicatively connected with a spatial light modulator in a phase control system, the phase control device of the holographic optical tweezers potential well stiffness is used to perform the phase control method of the holographic optical tweezers potential well stiffness according to any one of claims 1 to 7, and the device comprises: A decomposition unit, configured to perform plane wave decomposition of the electric field of the light trap according to the system configuration parameters if the input system configuration parameters are received, so as to obtain a corresponding decomposition matrix; A transformation unit, used for transforming the decomposed matrix expression according to a preset vector spherical harmonic function and a beam distribution of the spatial light modulator to obtain a corresponding matrix expression; A calculation unit, configured to calculate a Hermitian matrix expression corresponding to the matrix expression according to the beam distribution of the spatial light modulator; An expansion unit, used for expanding the stiffness coefficient of the light trap according to the Hermitian matrix expression to obtain a corresponding stiffness coefficient expansion expression; A phase optimization unit, used to optimize the phase of the spatial light modulator according to the pixel symmetry rule, the Hermitian matrix expression and the preset phase limiting condition to obtain an optimized phase value; A control instruction sending unit, used for generating a corresponding control instruction according to the optimized phase value and sending the control instruction to the spatial light modulator to perform phase control on the spatial light modulator; A coefficient value calculation unit, used for recalculating the coefficient value of the stiffness coefficient expansion expression according to the beam distribution of the spatial light modulator after phase control; The return execution unit is used to return to the step of performing phase optimization on the spatial light modulator if the coefficient value or the number of optimization times meets the preset iterative optimization condition, so as to perform iterative phase optimization on the spatial light modulator.

9. A phase control system for the potential well stiffness of holographic optical tweezers, characterized in that: The system includes a controller, a laser, a beam expander, a half-wave plate, a polarization fractional cube, a spatial light modulator, an objective lens and a camera; The laser is used to emit a laser beam, the beam expander is arranged downstream of the laser, the polarization fractional cube is arranged downstream of the beam expander, and the half-wave plate is arranged between the polarization fractional cube and the beam expander; The spatial light modulator is arranged downstream of the polarization fractional cube mirror, the dichroic mirror is arranged downstream of the spatial light modulator, and the objective lens and the camera are arranged on both sides of the dichroic mirror respectively; The controller is in communication connection with the spatial light modulator, and the controller includes a processor, a communication interface, a memory and a communication bus, wherein the processor, the communication interface and the memory communicate with each other via the communication bus; Memory, used to store computer programs; When the processor executes the computer program stored in the memory, the steps of the phase control method of the holographic optical tweezers potential well stiffness as described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the phase control method of the holographic optical tweezers potential well stiffness as described in any one of claims 1 to 7 are implemented.

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