| 摘要 |
Remote sensing in an environment having temperatures greater than 300° C., using an optical fiber having a core ( 10 ), a cladding ( 20 ), and a metallic protective coating ( 30 ) on the cladding to protect a surface of the cladding, the cladding having a diameter greater than 150 mum, and a thickness of at least 50 mum. The larger diameter cladding means stress from the metallic protective layer can be reduced, giving lower optical loss and better hydrogen protection. A metal conduit ( 330 ) encapsulates the sensing fiber, and a pump evacuates the conduit to reduce hydrogen seepage. Ceramic splice protectors are used. OTDR is used to determine differential loss at different locations along the fiber. A reflective element at the far-end of the fiber eases calibration.
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