Optical fibre temperature sensor in the cryogenic range

The realization of an optical fibre sensor applied to cryogenic temperature measurement in harsh environments is presented. The measurement principle is based on the analysis of the decay-time of the fluorescence emitted by special doped crystals, the excited state lifetimes of which are greatly dependent on temperature. The sensor is intended to work in the presence of strong perturbations encountered on the testing benches of the liquid hydrogen and liquid oxygen turbo-pumps of the Ariane 5 Vulcan engine developed by `la Societe Europeenne de Propulsion (SEP)?.