PHOTOREFRACTIVE CORRELATION FILTERING OF TIME-VARYING LASER SPECKLES FOR VIBRATION MONITORING

We proposed and experimentally studied a technique of vibration object monitoring. The technique is based on self-diffraction of the speckle pattern on the adaptive correlation filter recorded in photorefractiv e Bi12TiO20 crystal. This filter is recorded owing to the light-induce d scattering known as fanning effect. The proposed technique is as sen sitive as interferometric systems and it is very simple for implementa tion: neither reference nor readout beam is needed for operation. It i s shown that the system has a linear response on the lateral displacem ent of the object surface and its dynamic range can be easily varied d epending on experimental conditions. (C) 1998 American Institute of Ph ysics.