Dynamic Properties of Adaptive Optical Systems

Abstract

Dynamic (temporal) characteristics of adaptive systems imaging through the turbulent atmosphere are analyzed. The Strehl parameter is analytically calculated on the basis of the generalized Huygens–Kirchhoff principle. The conventional adaptive system with finite frequency band (or finite response time) is described as a dynamic system with constant delay. It is shown that to provide efficient distortion correction in such adaptive system, the time delay must be much less than the transport time of the coherence radius, corresponding to the average wind velocity, through the optical beam. Adaptive optical systems in which correction phase is calculated using not only the signal, but also its derivatives are also considered. It is shown that such modernization of the control algorithm of correction for phase front distortions admits much greater time delays. The time gain compared to the system with constant delay is the higher, the stronger are phase distortions in the optical wave.