Wide-field-of-view adaptive optics

摘要

Abstract: One of the most significant limitations to conventional atmospheric compensation systems is their very restricted field of view (FOV), generally equal to an isoplanatic patch size. A wavefront sensing and compensation concept is proposed that should allow the FOV to be increased in size by factors of ten or more. The kernel of the idea is to use wavefront measurements in several ($APEQ@9) directions separated by 100 - 200 $mu@rad to deduce an estimate of the three dimensional optical path difference (OPD) distribution in the atmosphere. The algorithms are roughly based on those used for medical tomographic imaging. Preliminary analysis indicates that from 9 measurement directions it is possible to estimate the OPD contributions from approximately six altitude layers. Once this 3-D OPD distribution is calculated, it may be used to deconvolve wide FOV short exposure images (i.e., wide FOV speckle holography) or it may be used to derive the drive signals for a suite of deformable mirrors that are conjugate to their respective altitude slices. Initial indications are that the FOV may be increased to 500 $mu@rad for a 3.5 m telescope operating at 0.8 $mu@m. Further, since the OPD contribution in each layer is smaller than the full atmosphere, the requirements on the system performance are somewhat relaxed. !4