Reciprocity principle and adaptive control of optical radiation parameters

Several simplest variants of application of adaptive control of the parameters of a beam are suggested. They are based on the application of the principle of reciprocity of propagation of radiation in an inhomogeneous medium. Information on the necessary correction of a wavefront reaching an object is obtained from the intensity distribution in the image plane of the object. The problems of guiding the axis of a bounded beam and its focusing are considered.