OPTICAL FIBRE SENSOR SYSTEM

摘要

An optical fibre sensor system comprising a transmitter, a receiver and a sensor interconnected by an optical link. An optical source at the transmitter transmits to the sensor via the optical link two optical signals at different wavelengths. The sensor transmits to the receiver via the optical link measurement and reference signals, the measurement signal being derived by modulating the intensity of one of the two optical signals in dependence upon a parameter monitored by the sensor and the reference signal having an intensity which has a predetermined relationship with the intensity of the other optical signal. The receiver compares the intensities of the measurement and reference signals to derive a measure of the monitored parameter. The two wavelengths are selected such that changes in the intensities of the optical signals resulting from variations in the temperature of the optical source are minimised or are of substantially equal magnitude for both the optical signals.