Research On The High Precision Segmented Calibration Mechanism Of Space Primary Mirror

Due to the reasons of mirror blank manufacturing,optical processing,transportation and adjustment,large aperture telescopes over 8m can only use segmented mirror technology.For large-scale segmented mirror telescopes,the detection and adjustment of the out-of-plane displacement and in-plane displacement between the segmented mirrors are the key points and difficulties.Based on the optical system of the 9m-aperture segmented mirror technology telescope,this thesis designs a high-precision segmented calibration test bench on the ground to meet the needs of stitching the six degrees of freedom of the space primary mirror,and proposes white light interferometry and lithography alignment technology combined schemes for segmented detection.The main research content is divided into the following parts.1.The segmented optical mirror structure of the 9-meter space telescope is introduced.According to the segmented accuracy and movement requirements of the space telescope,a segmented optical mirror measurement method based on displacement and tilt detection,two segmented test benches design including a motion system,a submirror out-of-plane measurement system,a sub-mirror in-plane measurement system,and a mechanical system are proposed.By comparing the detection scheme of one full coverage detection,the segmented detection scheme of partial coverage and multiple detections was selected;this scheme is reliable,the equipment can be lightweight,the processing cost is low,and the precision is high.2.The segmented calibration test system of the space primary mirror consists of three parts: the calibration mirror module,the visual marker positioning system,and the mechanical system.Through the interactive pose transfer between the sub-mirror and the calibration mirror,the stitching of the primary mirror is completed;through the detection and processing of laser displacement sensors,fiber optic probes and photolithography marks,the control of the position and posture of the sub-mirror and the calibration mirror by the hexapod is completed.The machine vision positioning solution uses cameras,lenses,light sources,etc.to collect images.The mechanical system adopts a custom-made air bearing shock absorber for shock isolation,XZ linear slide rails to provide linear motion,and a high-precision step-by-step rotary table to ensure 360-degree rotation covering all sub-mirrors.The connection between the hexapod,the turntable and the slide rail is completed through the turntable connector and the slide rail truss support structure,and the visual marking positioning system is carried at the same time.3.Established a simulation model for error analysis of segmented primary mirrors,deduced theoretical formulas for out-of-plane measurement of segmented telescope submirrors and calibration mirrors,and made detailed error analysis on translation errors and tilt errors of segmented mirrors and calibration mirrors.By selecting the accuracy and mutual position of the sensors,the translation error and tilt error of the segmented mirror can be calculated simply,quickly and effectively with high precision,and two methods to improve the segmented accuracy of the segmented primary mirror are proposed.In this thesis,the scheme design and theoretical simulation analysis of the highprecision segmented calibration system for the space primary mirror are carried out,which has guiding significance for the design,processing,testing,and adjustment of the segmented primary mirror calibration system.