Turbulent surveillance-or how to see a Kalashnikov from a safe distance

Abstract

Combining adaptive optics, real-time adaptation of system parameters, multiplexed imaging, and real-time processing solves the problem of imaging through turbulent atmosphere. Adaptive optics (AO) is the first choice technology for correction of dynamic optical aberrations. It can be directly applied to the isoplanatic aberrations, introduced in the optical system itself, and in the close vicinity to the aperture, where the turbulence is still isoplanatic. There are two ways to control the AO system, phase conjugation and optimization. Phase conjugation needs a bright point-like source for wavefront measurements. Optimization relies on real-time trial and error search for the shape of the wavefront corrector that maximizes the quality metrics in the image. To achieve uncorrelated input data, the observation should be done through different realizations of the turbulent atmosphere, by introducing delays between frames, or by splitting the pupil of the optical system to create multiple images through different turbulent paths.

Publication
Laser Focus World

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