Numerical Calculation And Analysis Of Optical Force Of Micro/Nano Structures Under Multi-Directional And Polymer Conditions

In this thesis,the finite element method is used,the Davis Barton fifth order approximate Gaussian beam incident at any angle is used as the light source,and the Maxwell stress tensor method is used for post-processing.With the help of the stacked matrix LU decomposition algorithm based on nested subdivision technology,the equations are directly solved,so as to efficiently solve the light forces on different target objects.This thesis first provides a brief introduction to the implementation steps of the finite element method and the specific solution process for calculating optical force using the finite element method.After comparing several methods for solving optical force,a suitable method was selected.The emphasis is on the Maxwell stress tensor method and its finite element representation.In the field of biomedicine and other research on the application of particles or cells,it is usually not possible to only consider the case of axisymmetric incidence of the incident beam,as the actual situation is often more complex.In some special cases,in order to obtain accurate values of the interaction between the incident beam and the micro/nano structure,it is necessary to discuss the effect of the beam incident at any angle on the micro/nano structure.Therefore,this thesis combines Gaussian beam with coordinate system rotation theory to improve the original single direction incident light source and achieve the analysis of the light force on micro/nano structures under Gaussian beam incidence at any angle.This makes the simulation results based on the method used in this thesis more consistent with the actual situation,and can provide a certain theoretical basis for using optical tweezers technology to operate and capture micro/nano structures.The complexity of multi particle systems leads to an increase in the complexity of their theoretical calculations,greatly reducing computational efficiency.In order to avoid the increase of computational complexity caused by the structural complexity of the polymer system as much as possible,this thesis introduces the layered matrix LU decomposition algorithm based on nested subdivision technology to improve the solution efficiency by establishing the three sphere system and seven sphere system model of the multi particle system,and further analyzes the optical parameters of Gaussian beam and particle attributes The influence of position and other factors on the light force it is subjected to.The comparison between the above algorithm and traditional iterative solving methods verifies that the algorithm proposed in the text has shorter computational time and lower memory requirements.At the same time,simulation conclusions can also provide theoretical support for the actual experimental process in terms of parameter selection.