Research On The Measurement Of Alignment Of The Deployable Telescope Secondary Mirror

At present, the deployable space telescope, due to its small volume during launch,become an important area of research. A typical type of deployable telescope is thatonly the support structure linking the primary mirror and secondary mirror can befolded. Before launch, the secondary mirror support structure is folded or compressed,the telescope becomes short and compact. On orbit, the secondary mirror part ismoved to the design location. This type of deployable telescope, because of its smallsize, light weight, the micro-satellite platform compatible, low launching cost, is moreand more attractive. It can be widely used in space optical communications, earthobservation field.In this paper, firstly a type of deployable space telescope which uses tape springs asthe support structure was presented, and an optical system was designed. Because ofthe deployment errors of the tape springs after deploying, the secondary mirror ismisaligned. Therefore, the influence on the imaging quality of secondary mirrormisalignment was analyzed.A measuring system for this type of deployable telescope was designed. It was used tomeasure the movement of the secondary mirror (secondary mirror misalignment) afterlunch. Based on the position sensitive detector (PSD), the measuring system consistsof three semiconductor lasers, three small mirrors, and three PSDs.. With ray tracingmethod, the equations linking the secondary mirror misalignment and PSD outputswere derived, and another new method based on matrix optics theory was alsopresented.Finally, the secondary mirror misalignment of this type of deployable telescopestructure was tested with an experiment apparatus. The results showed that the misalignment is about100μm level. The measurement error of the measuring systemwas analyzed.At the end of this paper, the main research work was summarized, and the futureworks were proposed.