Abstract

The formation of direct, high-resolution stellar images is severely limited due to the presence of atmospheric turbulence. Such turbulence causes random perturbations of a wavefront propagating through the atmosphere. Direct stellar images therefore consist of low spatial frequency information only and any detailed object structure is lost. In an attempt to overcome this problem a number of indirect image-forming techniques have been proposed in the literature. The present work is a comparative study of a few of these. The methods, in general, consist of averaging a quantity that is dependent on a transfer function which has significant value at all spatial frequencies out to the telescope diffraction limit. In particular the relative merits of the triple correlation techniques of Lohmann et al.¹ and the method of Knox and Thompson² are studied. The signal-to-noise ratios for both high light level and photon-limited images are compared between each technique.

© 1986 Optical Society of America