WIDENING THE EFFECTIVE-FIELD OF VIEW OF ADAPTIVE-OPTICS TELESCOPES BYDECONVOLUTION FROM WAVE-FRONT SENSING - AVERAGE AND SIGNAL-TO-NOISE RATIO PERFORMANCE

A fundamental problem of adaptive-optics systems is the very narrow co rrected field of view that can be obtained because turbulence is exten ded in altitude throughout the atmosphere. The correctable field of vi ew is of the order of 5-10 mu rad at visible wavelengths and increases as the wavelength increases. Previous concepts to broaden the correct ed field of view have been hardware oriented, requiring multiple wave- front sensor (WFS) measurements to control multiple deformable mirrors . We analyze the average and the signal-to-noise-ratio performance of an image measurement and postprocessing technique that uses simultaneo us measurements of a short-exposure compensated image measured in an o ff-axis direction; an additional WFS measurement is taken in the off-a xis direction. Results are presented for infinite-altitude WFS beacons driving both the WFS for the adaptive optics and the WFS looking in t he off-axis direction, a variety of seeing and WFS light-level conditi ons, and off-axis angles from two to six times the isoplanatic angle. This technique improves the average effective transfer function out to a field angle of at least six times the isoplanatic angle which provi ding a higher signal-to-noise ratio in the spatial frequency domain.