PURPOSE: To shorten the measuring time by successively allowing a light pulse signal to be incident on an optical fiber before the time when back scattered light ceases to return from the optical fiber and separately measuring back scattered lights.
CONSTITUTION: A light pulse tester is equipped with a pulse control signal generator 3 generating a burst signal 13 that let sine waves with (n) kinds of frequencies Δf last only for a finite time, and a light modulation part 4 receiving the input of signal light 11 and converting the signal light 11 to a light pulse signal 14 wherein the light frequency of the signal light 11 is shifted by the aforementioned frequencies Δf only for the certain time of the burst signal 13 and further equipped with (n) band-pass filters 8 filtering (n) kinds of frequencies Δf set by the pulse control signal generator 3 and a signal processing part 9 taking out the outputs of (n) band-pass filters 8 to average them.
MATSUURA SATOSHI
TAKEDA TOSHIYUKI
