Arbitrarily Small Pupils in Layer‐Oriented Multi‐Conjugate Adaptive Optics

Abstract

Layer-oriented Multi-Conjugate Adaptive Optics (MCAO), from a strictly optical point of view, is a sort of three-dimensional anamorphic relay of the atmosphere in which the turbulence is sensed within a small volume where a few detectors can be placed in a variety of combinations discussed elsewhere. In its original form, this approach imposes a practical limit on the minimum size of the reimaged pupils and hence requires large-format detectors with an equivalent pixel size that can be 1 to 2 orders of magnitude larger than what is available using the current technology. We show here that such a limit can be easily overcome without losing any of the advantages, both practical and fundamental, offered by the layer-oriented approach. Some alternative techniques, characterized by some practical disadvantages, are sketched in order to possibly inject new ideas into the MCAO domain. © 2005. The Astronomical Society of the Pacific. All rights reserved.