What is a fiber optic cable tester?
A fibre optic cable tester is a hand-held troubleshooting device that sends red light from a semiconductor laser (635nm) down a fiber to check for faults such as cracked fibers or defective splices. The visible red light travels along the fibre core until it reaches a fault, where it leaks out of the fiber. Light leaking through the fault can be seen through plastic coatings and jackets under suitable illumination. Infrared light in the signal leaks out at the same point, but your eyes cannot see it. The tester emits Class II red laser beam, making the light escaping from the damaged fiber easily visible from a distance. Attenuation of glass fibres is much higher at 630 to 670nm wavelengths of red light than in the 1300 to 1650nm transmission window, but the red light can still travel up to 5km through standard fibers. Note that the fibers must be exposed to use fiber optic cable tester effectively. If the red light leaks out inside a thick cable wrapped in black plastic, you can’t see
