Development of wavefront sensing system for high order AO system

Abstract

The ground-based stellar astronomy suffers from the atmospheric turbulence diminishing minute details in the images taken of celestial objects. Adaptive Optics is a tool that comes to the rescue of the astronomers who wish to overcome the limitations imposed by the atmospheric turbulence on the achievable resolution of the telescope. The work presented in this report deals with the design and development of a Shack-Hartmann wavefront sensor for higher order adaptive optics for 1.3m JCB telescope. Using a 2-dimensional lenslet array, a wavefront distorted while propagating through the atmosphere is mapped on the detector camera of an sCMOS type. The centroid of each lenslet is detected and then compared with the reference position. The distorted wavefront is corrected by deformable mirror (DM) through a dedicated control system. This is controlled through a graphical user interface in real time. Further in this project, the Hamamatsu sCMOS camera is characterized for its frame rate, noise characteristics and performance to ascertain its usefulness for the AO wavefront sensing. The photon count as a function of stellar magnitude and SNR that can be achieved are discussed in the later chapters of this report.