The Research Of Optical Trapping On Particles By Bessel Beams

With non-contact capture,no mechanical injury,micro and nano manipulation,optical tweezers technique has aroused much attention since firstly discovered in 1986.It has been widely used in biomedical,physical science,materials science,chemistry and many other fields.With the arising of many novel optical fields,Bessel beam has become a hot topic in the study of optical tweezers technology in recent years due to such properties as nondiffracting,self-healing,etc.However,there still needs further analysis and calculation on the interactions with particles.Given this,we studied the optical trapping properties of particles acted by Bessel beams with different polarizations,as well as the influence factors on the optical pulling force.Based on the generalized Lorenz-Mie theory,we deduced and calculated the polarized Bessel beam-shape coefficients with regional integral approximation method.Combined the conservation of momentum and conservation of angular momentum,we studied the influence of linearly polarized Bessel beam on the capturing property of eccentric spherical particles,and analyzed the effects of the particle size,refractive index and other index parameters on the trapping force and the capture moment.Moreover,considering the impact of polarization,with the vector diffraction theory and Wolf-Richards integral,we acquired the beam-shape coefficients of the optical field that are from different polarization cylindrical vector Bessel beams after high numerical aperture lens focused.We also simulated function of the particle parameters,polarization,cone angle on the axial optical trapping force.Additionally,the influencing factors of the cylindrical vector beam on the negative pulling force and its realization conditions are also explored.In this work,our results could provide the theoretical theory to the optical capture experiments and also have great influence in the study of optical trapping characteristics of Bessel beam and optical traction.