Prototype segmented mirror telescope: a pathfinder of India's Large Optical-NIR telescope project

Abstract

To cater the need of growing astronomical community of India, there is a proposal to install 10-12m size optical-NIR telescope, equipped with state of the art back-end instruments . A telescope of this size is possible only, when primary mirror is made of smaller mirror segments. In order to get acquainted with segmented mirror telescope technology, at Indian Institute of Astrophysics Bangalore, we have initiated a project to develop a small prototype telescope made of small mirror segments. The proposed prototype telescope will use seven hexagonal mirrors, which will be supported by simple mirror support assembly and driven by indigenously developed voice coil based actuators. We also plan to make use of in-house developed inexpensive inductive edge sensor, which can precisely sense inter-segment relative displacement. The telescope mount is supposed to be Alt-Az and secondary mirror will be supported by trusses made of steel. The primary axes like elevation, azimuth and field de-rotator will be driven by direct drive motors. Though the primary objective of this telescope is to demonstrate the segmented mirror technology, however, we have designed the telescope in such way that it can also be used to a few dedicated science cases. The telescope is planned to be installed at Hanle, Ladakh India which is also a potential site for India's large telescope project. In this paper, we will present the progress made in opto-mechanical design as well development of other sub-systems required for the PSMT. The prototyping effort is one step toward realization of a large telescope in India and it is expected to be completed in two years period.