Distributed optical fibre sensing of temperature using time-correlated two-photon excited fluorescence
C. J. Dalzell, T. P. J. Han, I. S. Ruddock, University of Strathclyde (United Kingdom)
Distributed temperature sensing based on time-correlated two-photon excited fluorescence (TPF) in doped optical fibre is described. Counter-propagating laser pulses generate a TPF flash at the position of their overlap which is scanned along the fibre by a variable relative time delay. The flash is transmitted to one end where it is detected and analysed to yield the temperature from its thermal dependence. With the fluorescence power being completely independent of excitation pulse duration and temporal profile, the sensor does not require ultrashort excitation pulses for operation. There is potential for high spatial resolution as the length of the sensed region depends only on pulse duration. Preliminary results are presented for praseodymium doped single-mode fibre.
