| 摘要 |
An apparatus for detecting changes in chemical or physical parameters, comprises a sensing optical fibre having a core surrounded by a relatively sensitive cladding the absorption spectrum of which varies with changes in chemical or physical parameters when these are applied to the cladding, and a transmissive optical fibre having a core surrounded by a relatively insensitive cladding for connecting at least one end of the sensing optical fiber to a remote light source and a remote detector. The core of the sensing optical fibre has substantially the same diameter as the core of the transmissive fibre and the refractive indices of both the relatively sensitive and the relatively insensitive claddings are less than the refractive indices of the cores of both the sensing optical fibre and the transmissive optical fibre. The transmissive optical fibre can be made up of two optical fibres, one extending from each end of the sensing optical fibre to be connected at their remote ends to a light source and detector respectively. Alternatively, a single optical fibre may extend from one end of the sensing optical fibre, the other end of which is made reflective, the single transmissive fibre being connected to both sources and detector using a beam splitter. The apparatus may be provided 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, so as to provide a very slim flexible sensor which is useful where space is restricted, e.g. as a medical catheter probe.
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