Feedback in devices utilizing optically controlled spatial modulators

A description is given of a number of optical devices which can be used in interferometry, holography, and optical information processing. Feedback in an optically controlled spatial modulator makes it possible to stabilize the intensity of laser radiation (temporally and spatially), to make an intensity modulator, and to perform image filtering. Probably the most interesting is the realization of a dynamic memory which, in particular, can be used to convert an image into binary form. An important use for devices with feedback is to solve equations of mathematical physics.