Fiber optic external perturbation sensor with analysis of intermode coupling by ring-wedge photodetector

The construction and experimental results of fiber optic sensor using the ring-wedge photodetector is presented. As sensor head the sample of quasi-monomode optical fiber is used. Changes of intermodal interference condition, due to external perturbation, generated changes of output speckle pattern. This pattern differences are automatically recognized by neural processing. The pattern for neural processing is generated by suitable placed ring-wedge photodetector system.