| All-optical conveyor belt is a kind of special zonal region formed in space by the light force generated by laser,which can realize local restriction and optical manipulation of tiny objects.This region is similar to the conveyor belt of real objects.This all-optical conveyor belt can transport micro-nano materials to the designated location through the conveyor belt,and can control the transport speed and time of the transported materials.The transport object of this all-optical conveyor belt is tiny material,which has the advantages of no touch,no damage,easy manipulation,easy integration and so on.It has important applications in manipulating micron pellets,biological cells,biomolecules and some nanomaterials.At present,great progress has been made in this field.A collimated circular gaussian beam is transformed into a focused elliptic gaussian beam by a cylindrical lens.Then the focused elliptic linear gaussian beam is obliquely incident to the surface of the glass slide located in the deionized water,and an elliptic linear spot is formed on the surface of the glass slide.The particles attached to the transverse spot are constrained in the center of the spot by the gradient force of the beam.In the longitudinal direction,it is forced to move along the light spot by light scattering force and gradient force.This type of elliptical spot is called alloptical conveyor belt.In this paper,we study the characteristics of starting point,speed and time,direction and distance.In addition,the transport mechanism of this all-optical conveyor belt is studied theoretically using ray theory and geometrical optical model.Firstly,the light capture efficiency of the focused elliptical gaussian beam irradiating the particle vertically is calculated.When the beam enters the glass slide obliquely,the spot formed on the surface of the glass slide is approximately the focal plane of the beam.Then the light force generated by the beam's oblique incidence on the microsphere on the glass slide surface is analyzed.Theoretically,when the azimuth of the optical conveyor belt changes from-90 to 90 degree,the particles in the conveyor belt are always restrained by the direction pointing to the long axis in the transverse direction,and the light force in the longitudinal direction is always positive,which is consistent with the direction of the light beam projected on the plane.When the azimuth Angle is 90 degree,the particles are constrained in both transverse and longitudinal directions to the axis of the light spot,and the particles are constrained to the axis of the light spot.In the experiment,the particles located in the conveyor belt are all absorbed by the conveyor belt to the central axis and transported along the longitudinal direction to the area at the end of the optical spot.The area range is 10 mm,realizing the conveyor belt's function of multiple initial transport points.By changing the incident light power,the transport speed and time of the conveyor belt are realized,and the transport speed increases linearly with the increase of the light power.The azimuth of the oval-shaped spot is changed by rotating the cylindrical lens,so as to realize the transport direction of the belt.The experimental results show that this all-optical conveyor belt can be controlled in any direction within the 180 degree transport direction,and it is found that with the increase of azimuth,the transport speed decreases,and when it increases to 90 degrees,the speed is 0.The light time is used to control the transport distance of the conveyor belt,which can realize the transport within the range of 0 ~ 250 mm.Finally,the application of all-optical precise transport of single-particle and multi-particle microspheres to fixed point is demonstrated.The innovation of this research is:1.Beam the focused elliptic gaussian beam into the glass slide plane obliquely,and achieve alloptical micron particle conveyor belt within the two-dimensional glass slide surface;2.Based on the ray theory and geometrical optical model,the mechanism analysis method for the conveyor belt formed by the oblique incidence of the focused elliptical beam onto the glass slide is established;3.In the water environment,it realizes the transport of particles at any initial position on the transport belt,and the control technology of transport speed,time,distance and direction. |
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