Patent ID: 6771358
Filing Date: 2004-08-03
Classification: G01M,H04B

Abstract:
A branch line monitoring system for monitoring n (&gE;3) branch lines into which a predetermined wavelength of signal light is introduced by way of a branching device, said system comprising:a light source for emitting n channels of monitor light having wavelengths different from the wavelength of said signal light and different from each other; a monitor light introducing structure for introducing into each of said n branch lines by way of said branching device said n channels of monitor light emitted from said light source; n optical filters each functioning to cut off respective one of said n channels of monitor light but transmit therethrough the remaining (Nâˆ’1) channels of signal light and being provided so as to propagate said transmitted (nâˆ’1) channels of monitor light and signal light through respective one of said n branch lines; a backscattering light detector for detecting, by way of said n optical filters and said branching-device, respective backscattering light components of said (Nâˆ’1) channels of monitor light generated in each of said n branch lines from each of said n branch lines through-which said (Nâˆ’1) channels of monitor light transmitted through the corresponding one of said n optical filters propagate; and an arithmetic unit for specifying, based on a result of detection concerning backscattering light obtained by said backscattering light detector, at least a loss distribution state of each of said n branch lines along a longitudinal direction thereof.