Method for measuring optical attenuation

摘要

The optical reflector plates 11, 12 and 13 are fitted on the end of the fibre-optic cables 8, 9 and 10, respectively. An optical waveguide directional coupler 2, which has at least one common terminal A and at least two output terminals B and C, is located between an optical time-domain reflectometer 1 (OTDR) and the fibre-optic measuring cable 5. The output terminal B is connected to one end of the fibre-optic cable 6 and the output terminal C is connected to an optical reflector plate 4 via an optical variable attenuator 5, the attenuator being able to alter the optical attenuation of light passing through. The OTDR 1 emits a pulse of light to the common input terminal A and measures the optical attenuation of the fibre-optic measuring cable 5 by determining the differences in the intensity of the reflected light pulses which are reflected at the respective optical reflector plates 4, 11, 12 and 13. <IMAGE>