Multi-channel adaptive fiber-optical system for monitoring of fast processes in solid state

A measuring system for long-term registration of fast processes in solid state objects under mechanical stresses based on using several single-fiber multimode interferometers (SFMMI) as sensors is proposed. Multi-channel adaptive correlation filter based on photorefractive crystal is used for simultaneous processing speckle signals from SFMMI. Mutual influence of the neighboring channels in crystal is analyzed, and it is shown that the simultaneous processing of several channels can be performed by using a single photorefractive crystal, even if optical fields from different sources are overlapped inside crystal. Such important property of proposed filter as its adaptability allows to separate fast processes of crack generating from slow processes of stress accumulating inside deformed object.