Interference sensor and method of measuring a physical quantity using such an interference sensor.

摘要

An interference sensor passes radiation from a source (10) and a polariser (30) to a loop (40) of optical fiber so that radiation beams circulate in opposite directions around the loop (40) and interfere. The loop (40) contains an optical phase modulation (50) which imposes an optical modulation on the radiation beams circulating on the loop (40). A converter (70) detects the interfering and modulated beams and generates an interference signal which is then processed by an analyser (100). The interference in the loop (40) is dependent on rotation of the loop (40) and therefore analysis of the interference signal permits that rotation to be measured. In the present invention, the interference signal is (i) sampled at a frequency different from that of the optical modulation, or (ii) electronically modulated on the analyser at a frequency different from that of the optical modulation, or (iii) optically modulated in the loop (40) at a second optical modulation frequency. The analysis in the analyser (100) may be in the frequency domain (i.e. consideration being given to the frequency of the interference signal) or in the time domain, (i.e. independent of frequency). <IMAGE>