APPLICATION OF SINGULAR-VALUE DECOMPOSITION IN AVERAGE TEMPERATURE-MEASUREMENT USING FLUORESCENCE DECAY TECHNIQUES

Average, rather than point specific temperature measurement is importa nt in a number of industrial situations. In this work, a method to imp rove this type of measurement using the fluorescence lifetime-related mathematical parameter, the singular value (SV), is discussed in detai l. The analysis reported shows that with rare-earth doped fibers used as temperature sensor probe elements, for average temperature measurem ent, such a system works well especially when the lifetimes obtained f rom different sensing probes are very close to each other. The SV sche me, based on matrix theory, is important because the average temperatu re-dependent singular value possesses the characteristics of both high speed and high precision. Using the method, an average temperature se nsing scheme is demonstrated in experiments carried out over the regio n from 20 to 100 degrees C, in which Nd3+ doped fibers are employed as the intrinsic temperature sensor elements. When two temperature sensi ng probes are used in the measuring region, the precision determined f or the average temperature estimation is +/-3.6 degrees C. When three sensors are employed instead of two, the precision is similar at +/-3. 4 degrees C. Results obtained indicate that with more sensor elements used in the sensing region, the accuracy achieved is not diminished du e to the averaging effect in the measurement. (C) 1998 American Instit ute of Physics.