What is OTDRs?

An Optical Time-Domain Reflectometer (OTDR) is an optoelectronic instrument used to characterize an optical fiber. An OTDR injects a series of optical pulses into the fiber under test and extracts, from the same end of the fiber, light that is scattered or reflected back from points along the fiber. The strength of the return pulse is measured and integrated as a function of time, and plotted as a function of fiber length. OTDRs are commonly used for testing, documenting, and troubleshooting optical fiber networks.