We present a new optical frequency domain reflectometer based on a tunable
fiber laser with a very narrow linewidth (about 10 kHz). This instrument pe
rforms reflectivity measurements with -110 dB sensitivity and 80 dB dynamic
range. The narrow linewidth allows long-range measurements, at 150 m, with
a spatial resolution of 16 cm, At short range, about 5 m, the resolution i
ncreases to subcentimeter.