Polarimetric fibre sensor

摘要

PCT No. PCT/GB85/00017 Sec. 371 Date Sep. 5, 1985 Sec. 102(e) Date Sep. 5, 1985 PCT Filed Jan. 18, 1985 PCT Pub. No. WO85/03124 PCT Pub. Date Jul. 18, 1985.A polarmetric fiber sensor comprises a lead fiber (1) and a shorter length of sensing fiber (2). Both fibers comprise higly birefringent optical fiber having orthogonal eigen modes and are spliced together with their eigen modes mutually rotated by 45 DEG . The sensing fiber (2) has a reflective distal end (6). Linearly polarized light from a laser source (3) is launched into one mode of the lead fiber (1) and light reflected from the distal end of the sensing fiber is recovered from the other mode of the lead fiber via a beam splitter (7) and photodiode (8). The resulting electrical signal produced by the photodiode (8) corresponds to the modal birefringence of the sensing fiber (2) and changes in this birefringence are monitored by processing means (9) to detect changes in a physical parameter sensed by the sensing fiber.