Research On Wavefront Testing Of Large Aperture Space Optical Systems Based On Subaperture Scanning Technology

During the past few decades,researchers in optical engineering had witnessed the leap in modern optical systems designing and fabricating technology.Meanwhile,large aperture space optical systems had found their great applications in fields such as space technology or national defense technology.Currently,optical systems of higher capacity of light capturing and resolution are of increasing importance,and this results in the requirement of extremely large optical systems,which greatly increased the difficulty of corresponding fabricating and testing processes.Testing of large aperture optical systems under field conditions after final assembly is one of the most critical link of the developing of optical systems as barely no more adjustment or maintaining could be realized after launch(focusing excluded).Conventional testing methods include interferometric detection using large flat mirrors and detection via large collimators providing collimated beams.Both methods are suffering from the limitation of high cost and disturbance sensitivity which make them very difficult to carry out testing under field conditions.That is to say,developing new testing technology to achieve optical system wavefront testing under field conditions of lower cost is highly required.In this dissertation,a novel field condition testing method of lower cost cal ed Scanning Hartmann Technology(SHT)is explored.This method is based on traditional Hartmann method,applying a small aperture collimator to sample the whole aperture of the system under test via scanning which successful y avoids the involvement of large devices.When comparing with the common test methods that induce Modulation Transfer Function(MTF)as the indicator of the image quality of the system under test,the new technology could be much more intuitive by directly reconstructing the wavefront aberration of the system.Besides,this method shows satisfying precision under noise caused by air flow,temperature gradient or vibrations,which means good potential in testing under field conditions.The main work of this dissertation is as following:1.The new testing technology cal ed SHT is proposed on traditional Hartmann method.In this technology,small collimators are applied to scan over the whole aperture of the system under test.Corresponding theoretical and arithmetic research is held to achieve the wavefront re-construction and to explore the accuracy to SHT.Confirmatory experiments are held to verify the basic theory of SHT.2.The feasibility of SHT is analyzed via Matlab & Zemax simulation.Simulation test process is applied on the Zemax modal of the optical system used in confirmatory experiments.Different kinds of pointing error are analyzed via simulation and the result reveals the impact of pointing error to the testing result.The technical indicators of devices used in SHT experiments are verified by the simulation.3.The calibration of pointing error of the 2-D rails applied in the testing experiments is held.The online compensation system is designed and explored.Controlling system of high accuracy sensors and positioning system is developed via VB 6.0.Relevant verifying experiments are held to the compensation system.The results show satisfying compensation time and accuracy comparing with the simulation results which lay a sound foundation for future development of SHT.