Ruby-based decay-time thermometry: effect of probe size on extended measurement range (77-800 K)

A fluorescence lifetime-based fiber-optic thermometer has been designed and characterized to carry out wide-range and real-time-temperature measurements, over a region from 77 K (liquid nitrogen) to 800 K. Computer-assisted data acquisition and digital signal-processing techniques which are used permit the taking of real-time temperature measurements. The results of the study have shown that the use of a smaller-size sensor element is preferable to avoid problems due to the redistribution of fluorescence and thus any resulting errors in the calibration, which is compared with the results of theoretical models. The extension of the work to the lower temperature range (< 200 K) highlights this problem, which has not been discussed before in temperature probe fabrication. (C) 1997 Elsevier Science S.A.