Fibre optic cable damping measurement - determining time taken for light pulse to travel along cable and return to light detector

摘要

A measuring instrument and fixture is able to measure the damping characteristic of an optic fibre lead (7). The instrument consists of a pulsed light source or laser (2) focussed onto the end of the cable. The light is measured at the cable end (9) and at the light detector (15) when the light has been reflected back along the cable, using mercury as the reflecting medium. The instrument includes an electronic store (11) and calculator (16) so that the damping in dB/km can be directly calculated from the time the light pulse takes to travel from the connection (8) through the fibre optic cable and back to the connection (8).