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Return Loss Measurements with up to 70 dB Dynamic Range The N7753C optical return loss meter measures the optical power into and reflected from the device under test and calculates the return loss. Factory calibrated parameters let you instantly start with the return loss measurement. To provide most accurate measurements over a wide dynamic range, a power monitor and the built-in step-by-step guide simplify accurate user calibration and eliminate the effects of dark current and parasitic backscatter. Fast Swept-Wavelength Return Loss Measurements The N7753C is used together with an external single-mode fiber light source and can be synchronized with triggering from tunable laser sources to make wavelength-dependent measurements. This is enhanced with the 1M sample logging buffer and wide averaging time adjustment range of 1 µs to 10 s. The Lambda Scan Engine of the Photonic Application Suite will support this in future versions for advanced swept-RL and IL measurements with one or more sweeping tunable lasers to cover wavelengths from 1250 nm to 1640 nm. The N7753C includes two power sensors and fiber couplers to provide a direct measurement of the optical return loss. One sensor measures the optical power reflected from the device under test to the instrument while the other sensor monitors the optical power passing through the instrument to the device under test. The calibrated ratio provides the return loss.