OPTICAL FIBRE SENSOR FOR MEASURING A PARAMETER, METHOD OF EVALUATING SUCH A PARAMETER, AND APPLICATION OF THE SENSOR TO THE MEASUREMENT OF A GAS

摘要

-14-ABSTRACTA fibre optic sensor especially suitable for determining thegas content of a mixture comprises at least one optical fibre formeasuring a physical or chemical parameter sensitive to a changein an environment (E) within which the sensor is placed. Thefibre comprises a cladding (3), a core (5) surrounded by thiscladding, an axis (7) with a length in the direction of thisaxis, and, locally along its length, parts (9) with variationsin optical thickness forming an optical diffraction grating (10).At least one part of the cladding (3) comprises in itscomposition an active material whose optical properties vary asa function of the change in the parameter within the environmentwhere the sensor is placed. The active material may be aheteropolysiloxane. In order to analyse the change in theparameter, a reflectometric analysis may be provided.