Sensor system

摘要

PCT No. PCT/GB97/00807 Sec. 371 Date Sep. 16, 1998 Sec. 102(e) Date Sep. 16, 1998 PCT Filed Mar. 24, 1997 PCT Pub. No. WO97/37197 PCT Pub. Date Oct. 9, 1997A sensor system (10) incorporating an interferometer operates as an optical strain gauge. The system (10) is arranged to generate interferograms characterised by an optical path difference between light traversing a sensor arm (12) of the interferometer and light traversing a reference arm (58). Each arm incorporates a highly birefringent optical fibre (38, 58) capable of supporting light propagation at two velocities in two different polarisation modes. A first interferogram is generated between light coupled into the fast eigenmodes of each fibre and a second is generated between light coupled into the slow eigenmodes. Mean optical group delay ( tau MGD) and differential optical group delay ( tau DGD) of these interferograms are affected differently by temperature and strain and thus provide a means of discriminating between these attributes of the sensor environment. Thus simultaneous measurement of strain and temperature is achieved.