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 it.
This technique is particularly valuable in equipment bays and other places inside buildings where fibres are exposed.
Shining a flashlight beam down a multimode fiber can serve the same function, and has long been used to trace fiber continuity as well. However, the flashlight couples little light into a single mode fiber.
Whether installing or troubleshooting, the fiber optic cable tester is an essential tool that quickly and easily locates problem areas in fiber cables. By pinpointing the exact location of fiber damage, technicians can diagnose, troubleshoot, and fix the problem effectively. The cable tester is also used for conducting continuity tests and performing fibre identification.
The Continuous/Flash control button lets operators choose between continuous or flashing illumination.
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