| 摘要 |
PURPOSE:To improve the monitoring performance by coupling inspection light which is different in wavelength from signal light, separating the inspection light by an optical filter at the terminal side of a signal light beam line, and amplifying back scattered light based upon the incidence of the inspection light in front of a photodetector. CONSTITUTION:A distribution device 4 is installed in the signal light beam path L1 to couple the inspection light from a line monitoring device 3 with the signal light beam path L1, and an optical filter 5 and an amplifier 6 are connected on the terminal side of the signal light beam path L1 to amplify the signal light and also separate the inspection light. An optical filter 5 and an amplifier 11 are connected in front of the photodetector 9 in the inspection light beam path L2 of the inspection light monitoring device 3 to amplify the back scattered light of the inspection light and also separate and monitor unnecessary light. The inspection light is therefore separated by the optical filter 5 on the terminal side and amplified by the amplifier 11 without being inputted as noise to a terminal device 2, so the afterward addition and averaging processing time is shortened. Consequently, the monitoring performance is improved. |
