Optical Time Domain Reflectometer (OTDR) is a device that measures distance to a reflection surface by measuring the time it takes for a lightwave pulse to reflect from the surface. Reflection surfaces include the ends of the cable and breaks in the fiber. The OTDR measures the ratio of incident and reflected light power, or backscatter. By using this OTDR testing device you can figure precisely where a fiber optic link is broken. TRS-RenTelco offers a wide variety of OTDR test equipment to Rent, Lease, or Buy.