Long-gauge optical fibre strain sensor with distributed strain coupling

摘要

An optical fibre strain sensor (100; 200) includes at least one sensing unit (101) and a protecting member (5) encapsulating said sensing unit (101). The sensing unit includes: a sensing section (3) defined in a sensing optical fibre (1) and having a length (L1) such that it is capable of providing information on a global strain field in a corresponding length of a structure (10, 11) being monitored; fibre-holders (4) provided at both ends of said sensing section (3) and anchored to the fibre (1) so as to prevent any slipping thereof; and a hollow element (2) surrounding said sensing section (3) while allowing movements of the sensing optical fibre (1). The protecting member (5) has a length (L2) greater than a length of the sensing unit (101) and adheres over its whole length to the structure (10, 11) being monitored.