In summary, an Optical Time Domain Reflectometer is an instrument that uses the inner back scattering properties of an optical fiber to detect and categorize abnormalities. It does this by sending high-power pulses of laser light into the fiber and capturing the reflected light. It can also pinpoint the location of light loss in the fiber. OTDRs also have the advantage of only requiring one insertion point, which enables testing of installed fiber. CEL has a comprehensive portfolio of high-power lasers and Avalanche Photo Detectors (APD) for OTDR applications. These parts are cost competitive and available in various form factors.