Time-division multiplexed topology for michelson interferometer sensors to measure low-frequency measurands

A time division multiplexed topology capable of supporting eight sensors has been implemented using four Michelson interferometer sensor simulators and a transceiver link. The topology is illuminated by a laser diode and is designed to measure nonstatic measurands such as vibration. The topology ensures that the laser diode is adequately isolated from the light returning from the network. The phase sensitivity of the sensors is limited by the phase noise of the laser. Noise due to Rayleigh backscattered light mixing with the signal is significantly smaller than this phase noise. A demodulated sensitivity of 25 mu rad/root Hz at 1 kHz has been achieved using the ''differentiate-cross-multiply'' technique.