Correction of phase distortions in coherent optical systems by adaptation

A study is made of adaptive compensation of phase distortions in a randomly inhomogeneous medium when an unknown object of arbitrary shape is observed in coherent light. Maximization of the sharpness functions is used for this purpose. A sharpness function is proposed in which an object is illuminated by a field with a known distribution of the amplitude and phase, and maximization of the function is independent of the shape of the object. An analysis is made of secondary extrema and it is shown that for a large signal/noise ratio there is a maximum corresponding to compensation of distortions of the medium. The suggested practical adaptive scheme does not require significant modifications of the existing systems.