Fig. 3: Temperature sensing by the time-expanded ΦOTDR.
From: Time-expanded phase-sensitive optical time-domain reflectometry
a Dynamic temperature map around the perturbed area. b Experimentally obtained temperature profile around the maximum (blue line) and expected (dashed red line) profiles. The latter was obtained by assuming a constant temperature profile along the hotspot; thus, the square-shaped profile of the hotspot is convolved with the 2 cm resolution window given by the gauge length. This results in a triangular shape for the measured temperature profile
