Linear analysis of closed-loop field conjugation by decentralized multi-conjugate adaptive optics

摘要

Imaging through turbulence using adaptive optics (AO) is limited by scintillation, even with perfect wavefront sensing and reconstruction. Such errors can be mitigated in closed loop by multi-conjugate AO systems consisting of two phase correctors, each of which is driven by a pair of wavefront sensor phase measurements, along with an internal probe beam that samples the beam train along a common path while propagating in the opposite direction as the external signal beam or beacon wavefront that samples the turbulence. Such decentralized architectures avoid not only direct measurement and feedback of irradiance but also intensive and/or highly coupled nonlinear control algorithms in favor of simpler, more conventional linear control laws. They also admit linear dynamical-systems modeling in the spatial-frequency domain. In this framework, coupled scintillation and servo-lag wave correction errors induced by turbulence are here predicted parametrically by scalably filtering and numerically integrating power spectral density profiles. The role of regularization is explored, and comparisons to previous nonlinear wave-optic simulation results are made.