Fibre-optic thermometer using sensor materials with long fluorescence lifetime

A fibre-optic thermometer using newly developed phosphor sensor materials is described. A highly sensitive fibre-optic fluorescence thermometer is developed using chromium ion (Cr3+) doped phosphor crystals with a longer lifetime than that of conventional ruby sensors. Long fluorescent europium doped strontium aluminate phosphors co-doped with various auxiliary activators (SrAl2O4:Eu2+, Ln3+, Ln = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu), were also grown and evaluated. In the fibre-optic thermometer using Cr3+ doped phosphor, PL lifetime decreased at temperatures ranging from 270 K to 750 K. The sensitivity of the fibre-optic thermometer varies with the host materials of Cr3+ ions. In the fibre-optic thermometer using SrAl2O4:Eu2+, Ln3+ doped phosphor, the value and lifetime of afterglow phosphorescence from the SrAl2O4:Eu2+, Ln3+ phosphors varied greatly in the narrow temperature region because the afterglow phosphorescence was dominated by thermal excitation of trapped carriers. Since the trap depth and the trap density depend on auxiliary activator elements, the sensitivity and temperature range of the fibre-optic thermometer using SrAl2O4:Eu2+, Ln3+ phosphors varied with auxiliary activator elements of SrAl2O4:Eu2+, Ln3+ phosphors.