Correlation-based fiber sensor using a holographic matched filter

The principle of a fiber sensor based on an optical correlation technique is described and assessed for its feasibility. The device measures the correlation between the far-field radiation pattern of a multimode sensing fiber and a reference pattern stored in a holographic matched filter. The output is a monotonically decreasing function of the changes in the patterns caused by the perturbance applied to the fiber. The results of some preliminary experiments are discussed and some drawbacks of the technique are pointed out