QUASIDISTRIBUTED FLUORESCENCE-BASED OPTICAL-FIBER TEMPERATURE SENSOR SYSTEM

The use of multiple material fluorescence-based sensors, where each is optimized to a particular temperature range yet is pumped by the same light source, emitting over the same spectral region, makes for a ver y simple, convenient and promising optical arrangement which can be ap plied in real-time, quasidistributed temperature sensor systems. The f luorescence lifetime approach, which is sin important technique to ena ble fluorescence emission to be exploited for thermometry, is adopted in the system discussed. An analysis scheme using Prony's method has b een reported which enables exponential decays from either single-mater ial or two material and quasidistributed sensors to be deconvolved and thus data and associated measurand information encoded in each indivi dual signal to be recovered. In this work, in the development of quasi distributed temperature sensor algorithms based on Prony's method are used for the estimation of exponential time constants of a convolved t riple exponential fluorescence decay, each corresponding to a differen t-point temperature. Experimental results obtained are presented to ju stify their use in practical multiexponential fluorescence decay analy sis and show a comparison of the Prony method to the Marquardt nonline ar least-squares approximation algorithm to achieve the deconvolution. The computational time for Prony's approach is approximately one-thou sandth that of the Marquardt technique while the accuracy achieved usi ng Prony's method is still high enough for practical use. (C) 1998 Ame rican Institute of Physics.