Simulation Research On Deterministic Polishing Of Fused Silica Based On Ion Beam

As optics is gradually being valued in the development of science and technology,the demand for optical systems and devices in all walks of life is also increasing,and the quality of optical systems is gradually improved with the progress of modern optical manufacturing technology.Among them,the surface quality of optical elements is one of the important factors that determine the imaging quality of optical devices,and its accuracy requirements are gradually increasing,reaching nanometer or even sub-nanometer level.As a deterministic figuring technology developed in modern times,ion beam modification plays an important role in the precision figuring of optical components because of its removal characteristics using ion beam as a removal tool.This paper uses computer simulation to study the ion beam figuring of fused silica glass material.The main research contents are as follows:(1)Research on ion beam figuring technology.First,this article introduces the ion beam figuring system,and elaborates on the structure and working principle of the radio frequency ion source used in ion beam figuring.Secondly,this article analyzes the influence of the various process parameters of the ion beam figuring equipment on the ion beam shape.Finally,through the Faraday cup scanning method,this paper verifies the stability of the working parameters of the ion beam equipment.(2)Research on the removal characteristics of fused silica optical components by ion beams.First of all,this paper analyzes the ion source removal characteristics through experiments such as single point etching,one-dimensional line scan,two-dimensional rectangular scan,etc.,and calibrates the stability of the ion source under different etching conditions.Then this article uses single-point etching combined with the removal function fitting algorithm to obtain ion beam removal functions without the diaphragm and with different beam diameters after the diaphragm is added.(3)Simulation study of ion beam figuring.First,according to the ion beam processing trajectory,this paper studies the relationship between the superposition fluctuation rate and the superposition coefficient through one-dimensional superposition simulation of ion beam figuring.Then this paper uses MATLAB tool to establish the mathematical matrix model of ion beam figuring and the optimization algorithm of residence time.(4)Ion beam figuring simulation and verification experiment.First of all,this article uses 16mm,12mm,8mm,5mm aperture ion beams to simulate and polish the fused silica element.The initial peak-to-valley value is 629.469nm and the root mean square value is 129.222nm.After simulation analysis,it is found that ion beams of different beam diameters have different shaping capabilities.The smaller the beam diameter,the more high-frequency errors can be corrected.Finally,a 12mm aperture was used to carry out the ion beam figuring verification experiment.The simulation accuracy peak and valley value was 80.62nm,and the root mean square value was 4.98nm.After 9 hours of figuring,the detection surface shape accuracy peak and valley value was 97.465nm.The root mean square value is 5.629nm,and the convergence ratio reaches 22.956.The experimental results show that the method of computer simulation figuring can not only accurately predict the shape of the processed surface,realize the deterministic modification of the ion beam,but also effectively improve the figuring efficiency of the ion beam.