Performance Analysis of the Wavefront Sensor in Active Correction of the INO340 Telescope

In large astronomical telescopes, the goal of the Active Optics System (AOS) is to provide correction of the telescope's low order aberrations at a low temporal bandwidth. In Active Optics Systems, the wavefront sensor (WFS) is used for the measurement of the telescope optical aberrations. In this paper, we discuss the measurement ability of the INO340's Shack-Hartmann WFS. During the altitude motion, the primary mirror is positioned at different angles. Due to the gravity and the high weight of the mirror, the surface of the mirror deforms from its ideal shape. We simulate the deformation of the primary mirror surface in ANSYS at different angles. Then through optical simulation, the angular displacements of Shack-Hartmann WFS's spots are calculated. Then based on the optical specifications of the telescope, the WFS, the guide star and the environmental conditions, we calculate the noise equivalent angle of the WFS, analytically. Finally, by comparing the angular displacement of Shock-Hartmann spots with the equivalent angle of noise, we analyze the performance of the wavefront sensor in terms of the altitude angle of the mirror, the magnitude of the guide star, and the Fried parameters.