Research On The Sensing And Control Of Support Forces In The Test Of Large Aperture Space Mirror

The demand for large-aperture mirrors is increasing in the space opto-mechanical system.The traditional test method which measure condition is different from the mirror service condition has not been able to meet the space-ground consistency measurement requirement of the large-aperture space mirror.The diameter enlargement and the extreme lightweight make the mirror with large aperture easily produce non manufacturing deformation under external forces.After removing the measurement system error,the optical path misalignment error,and the errors caused by the environment factors such as temperature,vibration and air flow,the rest result of the tested surface figure is the coupling of the support distortion and the processing residual.With different supporting forces,the figure test results of the mirror surface with same processing residual will be quite different.Strictly controlling the magnitude of support distortion in the test result is of great significance for improving the processing accuracy of mirror surface and ensuring the mirror figure consistency between in space and on the ground.This paper focus on requirements for real figure test of the large-aperture space mirrors,analyzes and studies the main mechanical factors in the ground measurement error of large-aperture space mirror,and aims to establish a set of support deformation error control and separation methods for high-precision surface measurement of large-aperture space mirrors,and to realize the test with effective separation of mirror support distortion,which should improve the country's test and manufacturing level of large-aperture space mirrors.The research work of this paper mainly includes the following parts.1.The main mechanical factors in ground measurement errors of large-aperture space mirror are analyzed,the control and separation methods of support deformation errors are studied.A support deformation error separation method based on the actual mechanical response of mirrors is proposed.2.In order to meet the optical axis horizontal test requirements of the large-aperture space mirrors,taking the 1.2m space mirror as an example,for the first time,an optical axis horizontal test platform with support force sensing and control functions has been built.The platform uses a flexible pressure mapping sensor to monitor and control the contact status in the mirror blind holes.Based on this platform,the optical axis horizontal test of the 1.2m space mirror was completed,and the support error separation experiment using the small-angle rotation method was performed.3.In order to verify the optical axis horizontal test results of the 1.2m space mirror and carry out the support deformation error separation experiment based on the actual mechanical response of the mirror,an optical axis vertical test platform was built.By the optical axis vertical re-test of the mirror,the credibility of the test result was improved and the support effect of the optical axis horizontal support platform is verified4.By using the optical axis vertical test platform,the deformation error separation experiment based on the actual mechanical response of the mirror is completed.By comparing the results obtained by the two different support deformation error separation methods,the effectiveness of the support deformation error separation methods was verified.