A non-contact particle grasping device and method based on focused vortex light

Abstract

This application discloses a non-contact particle grasping device and method based on focused vortex light. The device includes a laser, an attenuator, a beam expander and collimator, a half-wave plate, an achromatic cemented lens, a superlens, a focusing and collimator, a dichroic mirror, an objective lens, a sample stage, and an imaging mechanism arranged sequentially along the optical path. The laser light generated by the laser passes sequentially through the attenuator, the beam expander and collimator, the half-wave plate, and the achromatic cemented lens to reach the superlens. The superlens converts the laser light into topologically adjustable focused vortex light, which then passes sequentially through the focusing and collimator, the dichroic mirror, and the objective lens to reach the sample stage and grasp the particles on the sample stage. The imaging mechanism records the grasping process of the focused vortex light on the particles. This device can use the optical force of vortex light to grasp and manipulate tiny particles non-contactly, performing high-precision and complex manipulation of individual particles in three directions, avoiding damage to the sample caused by high-power lasers.

Description

Technical Field

[0001] This invention relates to the field of optical tweezers technology, specifically to a non-contact particle grasping device and method based on focused vortex light. Background Technology

[0002] Studying individual viral particles allows us to explore their behavior under different environments, better understand their biological properties, functions, and drug interactions, and is crucial for constructing in vivo behavioral models and developing diagnostic and therapeutic methods based on single viruses or single cells. Due to the size limitations of individual viral particles, manipulating them is a challenging technique. Studying individual viral particles typically requires single-particle tracking techniques, which allow for tracking, measurement, and analysis of individual particles, but do not enable active manipulation. To overcome this limitation, mechanical methods for cell manipulation have emerged, such as microneedles. These methods are not only highly destructive to samples and lack precision, but also require a high level of operator skill. In addition, there are electromagnetic field-based manipulation methods, such as electron beams and micro-magnetic beads, which minimize sample damage, but the equipment is expensive. Optical tweezers are a technique that uses a laser beam focused on the sample surface, utilizing the force of the laser to constrain particles and fix them at the focal point of the laser beam, thereby capturing or manipulating tiny particles. However, conventional optical tweezers can only move particles in a simple horizontal direction and are difficult to manipulate highly transparent biological samples. At the same time, excessively high-power lasers can often cause fatal damage to microscopic biological structures. Therefore, it is necessary to develop a high-precision, high-degree-of-freedom, and non-destructive single-virus particle manipulation platform. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a non-contact particle gripping device and method based on focused vortex light that can perform high-precision and complex manipulation of individual particles in three directions without damaging the particles.

[0004] To achieve the above objectives, based on one aspect of the present invention, a non-contact particle grasping device based on focused vortex light is provided, comprising a laser, an attenuator, a beam expander and collimator, a half-wave plate, an achromatic cemented lens, a superlens, a focusing and collimator, a dichroic mirror, an objective lens, a sample stage, and an imaging mechanism arranged sequentially along the optical path. The laser generated by the laser passes sequentially through the attenuator, the beam expander and collimator, the half-wave plate, and the achromatic cemented lens to reach the superlens. The superlens converts the laser into topologically tunable focused vortex light, which is then emitted. The focused vortex light passes sequentially through the focusing and collimator, the dichroic mirror, and the objective lens to reach the sample stage, grasping particles on the sample stage. The imaging mechanism records the grasping process of the focused vortex light on the particles.

[0005] In one embodiment, the superlens includes periodically distributed unit structures, each unit structure comprising a substrate and nanopillars located on the substrate surface, wherein any nanopillar of the unit structure satisfies the following phase equation:

[0006]

[0007] Where (x, y) represents the coordinates of any point on the superlens plane, f represents the focal length of the superlens, λ is the incident wavelength of the superlens, and l is the topological charge of the vortex light. The rotation angle of the unit structure is adjusted by the PB phase, and the phase of the unit structure... The relationship with the rotation angle θ of the nanopillar is as follows:

[0008] In one embodiment, the period P of the unit structure is 0.12 μm, the height of the substrate along the z-axis is 100 nm, the height of the nanopillar along the z-axis is 400 nm, the length along the x-axis is 0.1 μm, and the width along the y-axis is 0.055 μm. The substrate is made of silicon dioxide, and the nanopillar is made of silicon nitride.

[0009] In one embodiment, the superlens has a size of 3×3μm. 2 The focal length f is 2μm, the incident wavelength λ is 200nm, and the topological charge l is 2.

[0010] In one embodiment, the imaging mechanism includes a CCD camera, a spectrometer, and a display. The CCD camera receives light scattered from the sample stage to record the process of the focused vortex light capturing the particles. The spectrometer receives and analyzes the data recorded by the CCD camera, and the display shows the analysis data from the spectrometer.

[0011] In one embodiment, a first reflection mechanism is provided between the laser and the attenuator, the first reflection mechanism being used to reflect the laser generated by the laser to the attenuator.

[0012] In one embodiment, a second reflection mechanism is provided between the achromatic cemented lens and the superlens, the second reflection mechanism being used to reflect the laser emitted by the achromatic cemented lens to the superlens.

[0013] In one embodiment, a third reflection mechanism is provided between the focusing and collimating mechanism and the dichroic mirror. The third reflection mechanism is used to reflect the focused vortex light emitted by the focusing and collimating mechanism to the dichroic mirror.

[0014] In one embodiment, the beam expanding and collimating mechanism includes a first lens and a second lens, the focusing and collimating mechanism includes a third lens and a fourth lens, and the superlens is an ultraviolet superlens.

[0015] Based on the same inventive concept, the present invention also provides a non-contact particle grasping method based on focused vortex light, wherein sample particles are placed on a sample stage and a device is used to generate focused vortex light to grasp the sample particles, wherein the device is a non-contact particle grasping device as described in any of the above claims.

[0016] Vortex light is a type of light with orbital angular momentum and a complex phase structure. Specifically, the center of the beam's cross-section forms a spiral phase. Combining vortex light with optical tweezers technology can drive particles to rotate along specific circular orbits and can also move entire swarms of moving particles. Furthermore, because the orbital angular momentum carried by vortex light has non-zero components in three-dimensional space, it allows for highly precise and complex manipulation of individual virus particles in three directions. Moreover, the unique spiral phase wavefront of vortex light results in zero light field intensity at the center of the spot, creating a central void. This non-contact manipulation mode avoids damage to samples caused by high-power lasers and has great application potential in manipulating fragile single virus particles.

[0017] The non-contact particle grasping device and method based on focused vortex light provided by this invention can stably capture single virus particles or other microparticles with a diameter of nanometers. It can perform high-precision and complex manipulation of individual particles in three directions without contacting the tiny particles, avoiding damage to the sample by high-power lasers. It has great application potential in the manipulation of fragile single virus particles. In addition, it can not only capture virus particles and achieve sterilization and disinfection effects by increasing the energy of ultraviolet light, but also has the advantages of miniaturization and integration, promoting the development of optical tweezers technology in the biomedical field. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a non-contact virus particle grasping device based on focused vortex light according to an embodiment of the present invention.

[0020] Figure 2 Images captured by a CMOS camera showing a vortex beam capturing virus particles;

[0021] Figure 3 for Figure 1 A schematic diagram of the unit structure of the ultraviolet superlens in the non-contact virus particle grasping device shown.

[0022] Figures 4(a) to 4(b) for Figure 1 The following is an analysis of the focusing effect and focal length of the ultraviolet superlens in the non-contact virus particle grasping device shown. Figure 4(a) shows the focusing effect of the ultraviolet superlens in the xz plane, Figure 4(b) shows the focusing effect of the ultraviolet superlens in the xy plane, Figure 4(c) shows the light intensity of the ultraviolet superlens along the z-axis, with the strongest point being the focal point and the focal length being 3.5 μm, and Figure 4(d) shows the size of the focal spot.

[0023] Figure 5(a) shows Figure 1 The distribution of the force in the x-direction of the vortex beam applied to the particle in the non-contact virus particle grasping device shown is as follows: when the input optical power is 0.1W and a virus particle with a radius of 50nm is placed around the focal field of the superlens; Figure 5(b) shows the distribution of the force in the y-direction of the vortex beam applied to the particle.

[0024] Figure 6(a) shows Figure 1 The ultraviolet lens Ux in the non-contact virus particle grasping device shown in Figure 6(b) is... Figure 1 The ultraviolet superlens Uy is shown in the non-contact virus particle grasping device. Detailed Implementation

[0025] To make the technical problems, technical solutions, and beneficial effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0026] One embodiment of the present invention provides a non-contact virus particle grasping device based on focused vortex light, such as... Figure 1As shown, the system includes a laser, a first reflection mechanism, an attenuator (ND), a beam expander and collimator, a half-wave plate (HWP), an achromatic cemented lens (UDF), a second reflection mechanism, an ultraviolet superlens, a focusing and collimating mechanism, a third reflection mechanism, a dichroic mirror (DM), an objective lens, a sample stage, and an imaging mechanism, arranged sequentially along the optical path. Specifically, the first reflection mechanism is a mirror that reflects the laser light generated by the laser to the attenuator. The beam expander and collimator includes lenses L1 and L2. The second reflection mechanism includes mirrors M1 and M2. Mirror M1 reflects the laser light emitted from the achromatic cemented lens to mirror M2, which then reflects the laser light to the ultraviolet superlens. The focusing and collimating mechanism includes lenses L3 and L4. The third reflection mechanism includes mirrors M3 and M4. Mirror M3 reflects the focused vortex light emitted from the focusing and collimating mechanism to mirror M4, which then reflects the focused vortex light to the dichroic mirror. The imaging mechanism includes a CCD camera, a spectrometer, and a computer. The CCD camera receives light scattered from the sample stage to record the process of focused vortex light capturing particles. The spectrometer receives and analyzes the data recorded by the CCD camera, and the data obtained from the spectrometer is displayed on the computer. By connecting a CMOS camera to the computer, the laser-controlled particle motion can be displayed in real time, such as... Figure 2 As shown, the generated vortex optical tweezers can drag virus particles to move and exert a force on the virus particles.

[0027] like Figure 1 As shown, the laser light generated by the laser reaches the attenuator through a reflector. The attenuator controls the intensity of the light. After being expanded and collimated by lenses L1 and L2, it reaches the half-wave plate. After being modulated by the half-wave plate and enhanced by an achromatic cemented lens, it is reflected by reflectors M1 and M2 and reaches the ultraviolet superlens, generating a topologically tunable focused vortex light. The focused vortex light is then focused and collimated by lenses L3 and L4, reflected by reflectors M3 and M4, and reaches the dichroic mirror. It then enters the sample chamber through the objective lens to capture the virus. The capture process is recorded by a CCD camera. The CCD camera receives the light scattered by the sampling stage through a fiber optic probe, converts it into charge, and transmits it to the spectrometer. The data obtained by the spectrometer is displayed on the computer.

[0028] In this embodiment, the superlens includes periodically distributed unit structures, such as... Figure 3 As shown, the unit cell structure includes a substrate and nanoprisms located on the substrate surface. The nanoprisms of any unit cell structure satisfy the following phase equation:

[0029]

[0030] Where (x, y) represents the coordinates of any point on the superlens plane, f represents the focal length of the superlens, λ is the incident wavelength of the superlens, l is the topological charge of the vortex beam, the rotation angle of the unit structure is adjusted by PB phase, and the phase of the unit structure... The relationship with the rotation angle θ of the nanoprism is as follows:

[0031] In this embodiment, the period P of the unit structure is 0.12 μm, the height of the substrate along the z-axis is 100 nm, the height of the nanoprism along the z-axis is 400 nm, the length along the x-axis is 0.1 μm, and the width along the y-axis is 0.055 μm. The substrate is made of silicon dioxide, the nanoprism is made of silicon nitride, and the size of the superlens is 3 × 3 μm. 2 With a focal length f of 2μm, an incident wavelength λ of 200nm, and a topological charge l of 2, the superlens designed according to the above parameters can be used to grasp and manipulate most micro particles and has a wide range of applications.

[0032] The design of the superlens employs the geometric phase (PB) modulation principle. By adjusting the rotation angle θ of the lens unit structure using PB phase modulation, the superlens can generate a vortex beam carrying orbital angular momentum. The nanoprismatic column at any position (x, y) on the lens must satisfy the following phase equation:

[0033]

[0034] In this embodiment, right-handed circularly polarized light is used as the incident light. According to the principle of the Jones matrix, the outgoing light field of the unit cell structure is:

[0035]

[0036] Among them, E out It refers to the light field distribution of the emitted light. Let α represent the polarization state of light, α be the propagation constant, and the output light field contain co-polarized light with amplitude modulation only and cross-polarized light with phase modulation. The relationship between the rotation angle θ of the nanoprism and the phase response of PB is as follows: Therefore, θ needs to satisfy the following equation:

[0037]

[0038] This embodiment designs a focusing vortex ultraviolet lens with an incident wavelength of 200 nm and a topological charge of 2. The phase distribution of this superlens satisfies equation (1), and the size of the ultraviolet superlens is 3 × 3 μm. 2 With a focal length set to 2μm, a three-dimensional simulation was performed using the finite-difference time-domain (FDTD) method. The focusing effect of this superlens is as follows: Figures 4(a) to 4(d) As shown.

[0039] Optical momentum is an important dynamic property of electromagnetic waves. When a beam of light shines on a particle and is scattered, the transfer of momentum from the beam to the particle exerts an optical force on the particle. Typically, a vortex beam with a spiral phase factor exp(imp) carries orbital angular momentum (OAM). When focused by a high numerical aperture lens, it forms a ring-shaped focused spot, and particles near the focal point can be trapped on the ring with the highest light intensity. The optical force and trapping potential of the virus particles were calculated using the finite-difference time-domain (FDTD) method. The results show that the lens designed in this embodiment can stably capture HIV particles with a diameter of 100 nm. This ultraviolet superlens not only captures virus particles and achieves sterilization and disinfection by increasing the energy of ultraviolet light, but also has the advantages of miniaturization and integration, promoting the development of optical tweezers technology in the biomedical field.

[0040] In this embodiment, the ultraviolet superlens is used to capture virus particles with a diameter of 100 nm, and a simulation experiment is conducted based on this. Since the particle size selected in this simulation experiment is smaller than the wavelength, the Rayleigh model in electromagnetic theory is used for optical force simulation analysis. The time-averaged optical force acting on the particle can be obtained by considering the conservation of momentum of the system and integrating the Maxwell stress tensor on the closed surface S surrounding the particle, that is:

[0041]

[0042] In the formula, dσ and n represent the integral area element and the corresponding unit normal vector, respectively. The Maxwell stress tensor, expressed in SI units, is:

[0043]

[0044] ε1 and μ1 are the permittivity and permeability of the medium surrounding the particle, respectively. It is a unit tensor; E = E inc +E sca and H=H inc +H sca E represents the total field outside the particle. sca and H sca Represents the scattered field, while E inc and H inc This represents the incident field. E and H represent the electric and magnetic fields, respectively, both of which can be solved using the FDTD method. * H represents the conjugate of the electric field. * It represents the conjugate of the magnetic field.

[0045] The input optical power is set to 0.1W, and virus particles with a radius of 50nm are placed around the focal field of the superlens. The distribution of the x-direction force and y-direction force applied to the particles is as follows. Figure 5(a) ,5(b) As shown.

[0046] To evaluate the stability of the optical tweezers, the displacement integral of the optical force along the trapping direction can be used to assess the potential well depth U:

[0047]

[0048] Where F represents the optical force and x represents the particle position, the potential well depth U of the ultraviolet superlens was further calculated and compared with K. B T is normalized, where K B Here, is the Boltzmann constant (1.38e-23 J / K), and T is the temperature (300 K). Figure 6(a) , 6(b) The superlenses Ux and Uy are shown. This occurs when all potential well depth values ​​are greater than K. B At time T, it indicates that the designed ultraviolet lens can achieve stable 3D capture of the virus particles.

[0049] The non-contact particle grasping device and method based on focused vortex light of the present invention can stably capture single virus particles or other microparticles with a diameter of nanometers. It can perform high-precision and complex manipulation of individual particles in three directions without contacting the tiny particles, avoiding damage to the sample by high-power lasers. It has great application potential in the manipulation of fragile single virus particles. In addition, it can not only capture virus particles and achieve sterilization and disinfection effects by increasing the energy of ultraviolet light, but also has the advantages of miniaturization and integration, promoting the development of optical tweezers technology in the biomedical field.

[0050] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the embodiments of the invention as described above, which are not provided in detail for the sake of brevity.

[0051] The embodiments of this invention are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this invention. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of this invention should be included within the protection scope of this invention.

Claims

1. A non-contact particle grasping device based on focused vortex light, characterized in that, The system includes a laser, an attenuator, a beam expander and collimator, a half-wave plate, an achromatic cemented lens, a superlens, a focusing and collimator, a dichroic mirror, an objective lens, a sample stage, and an imaging mechanism arranged sequentially along the optical path. The laser beam generated by the laser passes sequentially through the attenuator, the beam expander and collimator, the half-wave plate, and the achromatic cemented lens to reach the superlens. The superlens converts the laser beam into a topologically tunable focused vortex beam, which is then emitted. The focused vortex beam passes sequentially through the focusing and collimator, the dichroic mirror, and the objective lens to reach the sample stage, where it grasps particles on the sample stage. The imaging mechanism records the process of the focused vortex beam grasping the particles. The superlens comprises periodically distributed unit structures, each unit structure including a substrate and nanopillars located on the substrate surface, wherein any nanopillar of the unit structure satisfies the following phase equation: Where (x, y) represents the coordinates of any point on the superlens plane, f represents the focal length of the superlens, λ is the incident wavelength of the superlens, and l is the topological charge of the vortex light. The rotation angle of the unit structure is adjusted by the PB phase, and the phase of the unit structure... With the rotation angle of the nanopillar The relationship is ; The unit structure has a period P = 0.12 μm, the substrate has a height of 100 nm along the z-axis, the nanopillar has a height of 400 nm along the z-axis, a length of 0.1 μm along the x-axis, and a width of 0.055 μm along the y-axis. The substrate is made of silicon dioxide, and the nanopillar is made of silicon nitride. The superlens has a size of 3×3μm. 2 The focal length f is 2μm, the incident wavelength λ is 200nm, and the topological charge l is 2.

2. The particle non-contact gripping device based on focused vortex light as described in claim 1, characterized in that, The imaging mechanism includes a CCD camera, a spectrometer, and a display. The CCD camera receives light scattered from the sample stage to record the process of the focused vortex light capturing the particles. The spectrometer receives and analyzes the data recorded by the CCD camera. The display shows the analysis data from the spectrometer.

3. The particle non-contact gripping device based on focused vortex light as described in claim 1, characterized in that, A first reflection mechanism is also provided between the laser and the attenuator, the first reflection mechanism being used to reflect the laser generated by the laser to the attenuator.

4. The particle non-contact gripping device based on focused vortex light as described in claim 3, characterized in that, A second reflection mechanism is provided between the achromatic cemented lens and the superlens, the second reflection mechanism being used to reflect the laser emitted by the achromatic cemented lens to the superlens.

5. The particle non-contact gripping device based on focused vortex light as described in claim 4, characterized in that, A third reflection mechanism is provided between the focusing and collimating mechanism and the dichroic mirror. The third reflection mechanism is used to reflect the focused vortex light emitted by the focusing and collimating mechanism to the dichroic mirror.

6. The particle non-contact gripping device based on focused vortex light as described in claim 1, characterized in that, The beam expanding and collimating mechanism includes a first lens and a second lens, and the focusing and collimating mechanism includes a third lens and a fourth lens. The superlens is an ultraviolet superlens.

7. A non-contact particle grasping method based on focused vortex light, characterized in that, The sample particles are placed on the sample stage, and the device generates focused vortex light to grasp the sample particles. The device is the non-contact particle grasping device according to any one of claims 1-6.

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