Lead-in fibers are useful to locate short distance faults and making loss/attenuation measurement in real time mode. This document explains how to use lead-in fibers. Optical fiber cables are tested for attenuation using the cut back method (TIA 455-78) or back reflection. To be able to judge whether a fiber optic cable plant is good, one does a insertion loss test with a light source and power meter and compares that to an estimate of what is a reasonable loss for that cable plant. The estimate, called a "loss budget" is calculated using typical component losses for. Fiber loss can be also called fiber optic attenuation or attenuation loss, which measures the amount of light loss between input and output. This loss can be caused by a multitude of factors, ranging from intrinsic material properties to environmental conditions. The uses various types of network cables, including multimode and single-mode fiber-optic cable.
[PDF Version]