Investigation On The Correction Method Of Medium Frequency Error Of Face Shape Based On Ion Beam Processing

With the increasing demand for higher performance and precision of optical components in the field of technology,many challenges have been posed to the processing technology of optical components.Ion beam polishing has become one of the options for improving processing accuracy in traditional optical manufacturing due to its characteristics of stress-free and non-contact processing,in order to obtain optical components with higher surface shape accuracy.Ion beam polishing can quickly remove low-frequency errors to achieve surface shape accuracy,but it may introduce mid-to-high frequency errors during the processing,among which the mid-frequency errors make the light scattered at small angles,which reduces the image quality and clarity and affects the performance of the optical system,so it must be improved.This article studies the control of mid-frequency errors in the ion beam polishing process through theoretical analysis,simulation,and process experiments.The main research contents are as follows:Firstly,research on the evaluation method of the mid-frequency error.Common error evaluation methods are introduced and the evaluation parameter of mid-frequency errors,power spectral density(PSD),is elaborated in detail.The definition and calculation model of PSD are applied to develop a PSD program and verify its correctness.This provides a theoretical basis for analyzing the changes of mid-frequency errors in ion beam polishing.Secondly,analysis of the generation factors of mid-frequency errors and error simulation.Explore the reasons for the occurrence of mid-frequency errors in ion beam polishing and simulate trajectory errors caused by commonly used processing paths after multiple iterations,such as grid errors and ring errors.The distribution,amplitude,and frequency spectrum characteristics of these errors are analyzed to determine their impact on the power spectral density curve.The research aims to provide technical support for correcting mid-frequency errors in ion beam polishing.Thirdly,an experimental study was conducted to investigate the influence of ion beam process parameters on mid-frequency errors in K9 material.The stability of the ion beam removal function,the thermal effects on the mirror surface during processing,the machining spacing,and variations in the removal function beam diameter were analyzed for their impact on mid-frequency errors in K9 optical components.The experimental results showed that batch processing reduces the fluctuations in the removal rate caused by the self-heating of the workpiece.As the processing distance and the removal function beam diameter decrease,the overall mid-frequency errors of the processed component decrease,and the frequency range of errors that can be improved becomes higher.Finally,machining and mid-frequency error analysis of a parabolic mirror.By selecting appropriate parameters,a spherical mirror was machined into a parabolic mirror.During the machining process,a larger removal function beam diameter was used to quickly remove low-frequency errors,while a smaller beam diameter was used for higher precision shaping and improvement of mid-frequency errors.The experimental results showed that the parabolic mirror had high surface accuracy and the mid-frequency errors were effectively controlled.