Intrinsic doped fibre fluorescence-lifetime based high temperature alarm sensor

A fluorescence-based intrinsic fire alarm sensor system for determining local regions of high temperature has been demonstrated in this paper, the signal processing basis of which is using a correlation coefficient ratio scheme. Two separate sensor configurations have been illustrated, one of which is to use short, single lengths of fibre spliced into a network and the other a long single length of doped fibre, using typically Nd or Er doped fibre materials. The results show that the correlation coefficient ratio, R, is sensitive to the temperature excursion and will become smaller than unity and decrease with the increase of the local temperature. It is also been shown that the ratio R is related to the intensity of the fluorescence coming from the section of the fibre exposed to the high temperature from a fire.