Design and development of a mirror support system for prototype segmented mirror telescope

Abstract

The segment support system of any segmented mirror telescope is considered to be one of the most critical subsystem. The segment support not only holds the mirror without altering its figure, but also features mechanism which facilitate active alignment of the segments with the help of three linear actuators. We have designed and a developed a segment support system for a proposed prototype segmented mirror telescope (PSMT). The baseline design of the PSMT segment support comprises of nine point axially supporting whiffletree coupled with a moving frame and a central diaphragm for the radial support. Our design uses large number of flexural components including flex pivots which make it friction-less system, requiring no lubrication. In this paper we present the details of our design as well as results of very extensive finite element analysis carried out to explore effect of variable gravity as well as temperature on the performance of the support system. During the course of telescope movement from zenith to horizon, interplay between axial and radial support system has also been studied in great detail. The modal analysis is also carried out to determine different natural frequencies/modes the support system is subjected. Functional and operational aspect of the segment support is also tested by conducting experiments on one fully realized system. The segment support which is primarily designed for 0.5m size PSMT segment can be easily scaled up to 1 m size segment and hence can be used for any large telescopes aimed to utilize segmented primary mirror.