Research On Ion Beam Figuring Technology Of Aspherical

Aspheric optical elements are widely used in modern optical systems because of their excellent optical properties.Ion beam figuring is often used in the processing of aspheric surface with stable removal function,non-contact machining and high processing accuracy.In the ion beam triaxial figuring system,compared with the planar optical element,the removal function of the aspheric surface changes obviously,and the calculation method of dwell time is also different from that of the plane,so it is relatively difficult to process.In view of various problems in aspheric surface figuring,the establishment of removal function model on aspheric surface,calculation of surface deviation,path planning,dwell time solution and ion beam figuring calculation software design are studied in this paper.The main research work and conclusions are as follows:Firstly,based on the analysis of the principle of ion beam figuring,the effects of the surface curvature of aspheric surface and the incidence angle of ion beam on the removal rate in the triaxial figuring system were studied.The removal rate of the ion beam is mainly determined by the reference removal function and the incident angle of the ion beam.Secondly,the reference removal function is fitted by the least square method.Combined with the SRIM simulation and the point etching experiment,the dynamic removal function model on the aspherical surface of the triaxial system is established.The calculation method of surface deviation is improved by translation and truncation operation.The planning of raster and helical scanning trajectories is realized.The algorithm of dwell time based on dynamic removal function is studied,and the simulation analysis of aspheric surface processing in the ion beam triaxial polishing system is carried out.Then,using the c#language compiled the aspherical ion beam figuring software,realized the removing function fitting,surface shape deviation solving,ion source trajectory planning,dwell time calculation,and the generation of nc file functions to meet the needs of the actual processing,and the simulation analysis of the relationship between ion beam diameter,step and processing efficiency.Finally,the quartz plane of Φ 100mm was processed,and the PV value converged from 749.403nm to 277.053nm,and the RMS value converged from 104.316nm to 16.604nm.The spherical surface of Φ50.8mm was processed,and the PV value converged from 145.907nm to 68.316nm,and the RMS value converged from 25.483nm to 8.810nm.The ellipsoidal surface of Φ50.8mm was processed,and the PV value converged from 695.01nm to 367.29nm,and the RMS value converged from 180.04nm to 42.969nm.