Detection and/or measurement procedure for physical entities using a distributed sensor

摘要

Identical Bragg reflection gratings (4) are formed by periodic variations of the refractive index of the core of an optical fibre (1) over a length of e.g. 1 to 2 mm. The gratings are spaced e.g. 1 m apart and addressed by optical pulses (7) emitted from a laser source (5) into one end (1A) of the fibre via a coupler (6). The reflections are delivered to a receiver (8) linked to an oscilloscope (9). Any variation of the physical quantity in the vicinity of a grating is betrayed by consequential change in the time-varying intensity of the reflected energy.