<title>Synthetic aperture adaptive optics concept</title>

Abstract

A serious impediment to the development of large aperture optics systems for correction of atmospheric turbulence is the very large number of wavefront correction subsystems (each consisting of an actuator, an actuator drive circuit, and a wavefront measurement element) which are required, and the attendant cost of these subsystems. If wavefront correction is to be applied to a fully-filled circular pupil several meters in diameter, several thousand of these subsystems may be needed. This situation could, however, be ameliorated if the pupil were not fully-filled. Here, we demonstrate that the diffraction-limited resolution of a full circular pupil can be approached or equalled with a synthetic aperture optical system consisting of an elongated pupil which rotates. Separate exposures of the object scene are made at each of several rotational positions of the pupil, and the final scene is reconstructed for these exposures. No optical phase information is needed for the image reconstruction. The polished area corresponding to the elongated pupil could be an order of magnitude smaller than that of the full pupil, and thus the number of adaptive optics subsystems could be decreased by a similar factor. The technique does not allow us to reach the same limiting magnitude as does the full, diffraction-limited pupil. However, on somewhat brighter objects, it could achieve the angular resolution of the full pupil without the complication and cost of adaptively correcting the entire pupil.