Application of Hadamard transform to fiber optic smart-skin sensing

An array of optical fibers can be applied to smart skin sensing applications, which include stress monitoring, fatigue detection, temperature sensing, etc. Although a single light source can be used in a fiber array sensor, the input light power is divided by a sensing fiber array and each fiber may require a detector. Thus as the channel number of a fiber array increases, the number of detectors also increases and the signal intensity of each fiber channel decreases, which decreases the signal-to-noise ratio and increases the complexity and the cost of the system. In this paper, we analyze the Hadamard transform to enhance the signal processing of the fiber array sensor. The apparent advantages are: only one detector is needed and the signal-to-noise ratio of the fiber array sensor can be improved by a factor of √N/2, where N is the number of sensing fibers. Analysis for an array of 127 sensing fibers is illustrated, in which we have shown that the calculated results are in agreement with the analytical model.