An adaptive optics system for astronomical image sharpening

Abstract

Images of stars in the focal plane of large astronomical telescopes are many times larger than the images expected from diffraction theory. Much of this blurring of the image is due to variations in the optical properties of the atmosphere above the observatory which for small aperture telescopes causes motion of the image, and for large aperture telescopes causes the image to break up into a number of smaller sub-images. This thesis describes a prototype adaptive system which is designed to sharpen astronomical images in real-time. The sharpening is achieved by removing the atmospherically induced motions of the image with servo-looped plane mirrors driven by piezo-electric actuators. The results of real-time sharpening obtained with the adaptive system at the William Herschel Telescope (WET) are presented along with the results of an investigation into the characteristics of the atmospheric limitations at the La Palma observatory site.