ACCOUNTING FOR THE INFLUENCE OF THE CORRECTOR HYSTERESIS ON THE DYNAMIC CHARACTERISTICS OF ADAPTIVE OPTICS SYSTEMS
V.P. Lukin
V.E. Zuev Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, Tomsk, Russia
Keywords: adaptive optics, turbulent atmosphere, active corrector mirror, Strehl parameter, hysteresis
Abstract
This article is a logical continuation of the previous analysis of the dynamic characteristics of adaptive optics systems operating in a turbulent atmosphere, in particular, the influence of such an important factor of an active corrector mirror as its hysteresis is analyzed. An analytical approach is used to calculate the requirements to the dynamic parameters of the feedback loop of an adaptive system for focusing laser radiation through a turbulent atmosphere. The possibilities of using control algorithms in adaptive optics systems based on the description of their operation as a constant delay control system are considered. A corrector mirror model is used, which takes into account the time delay between the time of the signal and the time of its processing. To estimate the frequency of operation of the adaptive optics system, an analytical expression is used that relates the maximum achievable level of correction by the Strehl parameter with the most important system parameters: the accuracy and frequency of the wavefront sensor and the aperture size of the optical system, as well as with atmospheric parameters: the Fried parameter and the wind speed. The differences between two types of tracking loops are analyzed: open and closed loops in adaptive optics systems.
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