Optical fibre sensor.

摘要

An apparatus for detecting changes in chemical or physical parameters, comprises a sensing optical fibre (18) comprising a core surrounded by a sensitive cladding whose absorption spectrum varies with changes in the chemical or physical parameters when these are applied to the cladding, and transmissive optical fibre means (15, 16) comprising a core surrounded by an insensitive cladding for connecting at least one end of the sensitive optical fibre to a remote light source (19) and a remote detector (21), the core of the sensing optical fibre (18) having substantially the same diameter as the core of the transmissive fibre means (15, 16) and the refractive indices of both the sensitive and the non-sensitive claddings being less than the refractive indices of the cores of both the sensing fibre (18) and the transmissive optical fibre means (15, 16). The transmissive optical fibre means can be two optical fibres, one extending from each end of the sensitive fibre to be connected at their remote ends to the light source and detector respectively, or a single optical fibre extending from one end of the sensitive fibre whose other end is made reflective, the single transmissive fibre being connected to both sources and detector using a beam splitter.

Apparatus in the configuration of a probe having a reflective sensitive end, with one or more transmissive fibres extending for connection to a remote source and detector, provides a very slim flexible sensor which is useful where space is restricted, e.g. as a medical catheter probe.