Evaluation of a new method for metal embedding of optical fibres for high temperature sensing purposes

The degradation of high temperature plant components is controlled by many phenomena like oxidation, high temperature corrosion, creep, wear etc. For practically all kinds of degradation the rate increases with increasing temperature. This fact makes the temperature a very important parameter in component life management. A precise knowledge of the spatial distribution and temporal variations in the temperature field in high temperature components would greatly promote the application of modern life management as well as assist in process control. Fibre optic sensing inherently provides the possibility sensor networks, either as fully distributed sensing (the whole length of the fibre acts as sensor) or as quasi-distributed (certain elements along the fibre act as sensors). This article describes a method for metal embedding of optical fibres for sensing purposes. Two metal embedded in-fibre Bragg-gratings were thermally cycled between hold temperatures of 502°C, 527°C and 552°C for more than five months and the results are presented