Abstract

The LEST wavefront sensor described here is intended for control of the aberrations induced by slow variations in the mechanical structure of the telescope. Hence the effects of atmospherical fluctuations must be averaged out. Active control of LEST based on the sensor signals will be performed tilting the main mirror M1 (eliminating misalignment coma), translating M3 (eliminating defocus) and adjusting the supports of the active M1 (modal compensation of other aberrations). The sensor works according to the Shack-Hartmann principle. Hartmann shifts are determined from a least squares estimate of the slope of the cross correlation spatially spectral phase. The algorithm adapts automatically to the actual spectral content of the subimages, ie to both object structure and seeing conditions.

© 1995 Optical Society of America