Aligning and phasing segmented mirror telescope with the pyramid sensor

Abstract

Alignment and Phasing system (APS) is one of essential device for any segmented mirror telescope. It helps to align and phase mirror segments, so that all together they works like a monolithic surface. Over last two years we have been exploring a possibility of using pyramid based wave-front sensor in the APS of a Prototype Segmented Mirror Telescope (PSMT), being developed in India. As a first step, we have derived the basic mathematical formulations required for the pyramid sensor and then after simulated the functional aspects of the pyramid sensor in the MATLAB. In order to carry out experimentation on pyramid sensor, we have also designed an optical setup using the ZEMAX. Since manufacturing of a high quality pyramid is a challenge, therefore, we have come up with a simple scheme in which the PSF is divided into multiple pupils using a rotating mask. In this paper, we briefly present the mathematical formulation, the technique of wave-front reconstruction, various simulations using the MATLAB and the ZEMAX as well as results obtained through a preliminary experimentation.