Optical return loss (ORL) measures how much light reflects back in fiber optic systems. Higher ORL values indicate better transmission quality. Use specialized instruments like OTDR and OCWR to check for. Factory calibrated parameters, a power monitor and the built-in step-by-step guide simplify user calibration and eliminate the effects of dark current and parasitic backscatter to achieve most accurate measurements over a wide dynamic range. The N7753C is used together with an external single-mode. Beginning with software release 1. the reflection above the fiber backscatter level, relative to the source pulse, is called reflectance. When high-speed signals enter or exit a part of an optical fiber, such as an optical fiber connector, discontinuity and impedance mismatch may cause reflection, which is the return loss of an optical fiber. To. Optical Time-Domain Reflectometry (OTDR): OTDR is a widely used technique for measuring return loss. Optical Return Loss (ORL) measurement: ORL measurement involves measuring the ratio of the reflected. Reflectance (which has also been called "back reflection" or optical return loss) of a connection is the amount of light that is reflected back up the fiber toward the source by light reflections off the interface of the polished end surface of the mated connectors and air.