Research Of Testing Large Aperture Space Optical System

Along with the improvement of modern optical manufacture technology, thedigital image processing technology and the hardware&software of the computer,the development of the space optical technology is of high speed. Nowadays, theaperture sizes of space optical systems have been increased to achieve higherresolution and more light collecting capability for the military requirement and thespace science and technology. So the fabrication and testing of large aperture opticalsystem face a challenge. In common test, the system is tested using an interferometerthrough self-calibration. After the assembly of the entire system, a collimator isalways applied to provide a collimated test beam for the performance evaluation ofthe space telescope in the laboratory or in the field. Since space optical systems arenearly impossible to be repaired while they are operating in the space, the finalperformance test before set into the space is essential for a successful space opticalsystem development. However, along with the augment of aperture size and focallength of these systems, using collimator to test the system is becoming moredifficult for the essential problems of making and moving a larger collimator. Thus,it is highly desired to find another measurement with simpleness and high efficiencyfor the outdoor test.In this dissertation, a novel method for testing the large aperture space opticalsystem is proposed. This method is simple and easy to be realized. The main idea of this measurement is using the system under test to obtain the collimated beam fortesting by the internal target and a flat mirror. The taken images of the target containthe information of the system. The system wavefront error is calculated by phasediversity technique through imaging processing.The main work of this dissertation is shown as follow aspects.1. The new method for testing large aperture space optical system is proposedbased on the principle that the spherical wavefront emitted by the point lightsource, which is settled at the focal plane of the system, will become theparallel beam after passing through the entire system. Then the extendedtarget is used to replace the point light source in the practical scenario. Thephase diversity technique is applied for the digital image processing.2. The residual error and limitations of this measurement is discussed to showthe utilization potentiality of this approach.3. The simulation program of this optical system test and the computerprogram of phase diversity technique for image processing are established.The simulation is finished to show the feasibility of this method.4. The experiment project is designed using point light source and flat mirrorto test a Cook’s three-mirror anastigmatic system. The measurement isoptimized for the application.