Study On Key Processing Technologies For High Precision X-ray Mirrors

Synchrotron radiation sources with its high-throughput,high brightness,wide spectrum and other unique properties,are widely used in many cutting-edge science,and made a series of major scientific research achievements.In recent years,with the upcoming Beijing synchrotron radiation facility and hard X-ray free electronic laser device construction,and the secondary beam lines of Shanghai synchrotron radiation facility are under construction,higher requirements of surface accuracy and larger number of demand for X-ray mirrors are presented.At present,due to its own application characteristics,X-ray mirrors generally used the surface error slope as a measure and evaluation indicators.However,all of the models and calculations in computer controlled deterministic optical processing are based on surface error height.The contradiction between processing and detection has expedited the processing problem of high precision X-ray mirrors,and there is no such high precision X-ray mirrors processing capability at home.Therefore,this thesis focuses on the high-precision X-ray reflector processing problems,mainly carried out the following aspects of research work:1.The deterministic processing model based on the surface error slope is established.The machining problems of X-ray mirrors under traditional height-figuring model are studied by theoretical analysis and simulation.It is pointed out that the conversion of the raw slope data from measurement to error height required for machining,which will introduce the cumulative error of data conversion that cannot be ignored.The theoretical analysis and simulation results show that the data conversion cumulative error is the main factor to realize the high precision machining of the X-ray mirrors in height-figuring model.Therefore,a new figuring model based on the surface error slope was proposed and established.The model directly uses the initial measurement surface slope data as input for the deterministic process,to avoid the cumulative error of data conversion.Thus,the model precision is improved.2.The process solving problems based on slope-figuring model in one-dimensional machining mode are studied.The reasonable dwell time interval is determined by combining the machine tool motion characteristics.The efficient set method with constrained optimization problem was introduced to achieve the efficient and accurate solution of dwell time and the comprehensive optimization of machining implementation.3.The process solving problems based on the slope-figuring model in two-dimensional model are studied.Considering the characteristics of non-negative and slope removal functions of dwell time,the non-negative restart LSQR regularization algorithm was introduced.The optimal non-negative offset ratio parameters and iteration parameters are determined by using the prediction curve of residence time and machining residual.Comparison of simulation results of the same shape under slope-figuring model and height-figuring model.It is found that under the slope figuring model the slope residual error is better,the dwell time is shorter,but the machining height residual error is larger.4.Study on the figuring process and experimental of high precision X-ray mirrors.According to the slope requirement of X-ray mirrors,the optimized process route for combined machining was proposed,which is first processed by height mode and then processed by slope mode,and the modification experiment was carried out on silicon mirror.The experimental results verify the effectiveness of the solution algorithm in the slope figuring model,and explain the correctness of the new processing and new technology proposed in this thesis,which provides theoretical guidance and technical support for high precision X-ray mirrors processing.