EXTENDED RANGE PSEUDO-HETERODYNE DEMODULATION FOR FIBER OPTIC SENSORS

This article describes a pseudo-heterodyne demodulation technique for interferometric fiber optic sensors that has a larger measurement rang e than is currently possible with pseudo-heterodyne demodulation. This sensor demodulation technique has a bandwidth of 30 Hz to 2.5 kHz, is capable of resolving optical phase angles as small as 5 x 10(-4) rad, and has a maximum measurement range of tens of radians in a bandwidth of 30-500 Hz. A comparison between the response obtained from a resis tance strain gage and a fiber optic sensor using this demodulation is favorable.