CHARACTERISTICS ANALYSIS APPARATUS FOR BRANCHED LIGHT BEAM PATH, AND BRANCHED LIGHT BEAM PATH CHARACTERISTICS ANALYSIS METHOD

摘要

PROBLEM TO BE SOLVED: To measure individual characteristic distribution of a branched light beam path with high speed.;SOLUTION: A probe light pulse is made incident in advance to measure a difference ΔL_max between maximum and minimum lengths of a branched light beam path. X probe light pulses of an optical frequency (f₀-f_B) are made incident with a time difference of τ+2ΔL_max/ν or larger. A pump light pulse (frequency f₀) having a frequency different from the probe light pulse is then made incident, thereby to acquire a spectrum of a Brillouin gain generated by X times of collisions of the pump light pulse with the probe light pulse in the branched light beam path. After the measurement by a certain set Brillouin frequency shift(f_B) is completed, the measurement is repeated before reaching a set Brillouin frequency entire band (F_B) while a frequency difference between a probe light pulse train and the pump light pulse being changed by a set Brillouin shift interval (Δf), thereby acquiring a Brillouin gain distribution with respect to a distance direction. Thus, a characteristic distribution of the branched light beam path is acquired by measurement time of 1/X.;COPYRIGHT: (C)2015,JPO&INPIT