Fluorescence based optical fibre fire alarm system [for aeroengine application]

A fluorescence-based optical fibre fire alarm system, which offers the advantages of light weight and relatively low cost, has been discussed to address the specifications required for aeroengine fire detection. A temperature excursion as low as 50-100/spl deg/C has been detected and current spatial resolution achieved is /spl sim/20 cm. Lengths of 1.2 m of Er & Tm doped fibres have been tested and with a higher power laser diode in the future work an extension of the sensing length to the required maximum of 3 m seems possible. The referential method discussed has proved to be applicable under various testing conditions.