The basic process is straightforward: turn the meter on, set it to the correct wavelength, clean your connectors, plug in, and read the display. But getting accurate, meaningful results depends on understanding a few key details about wavelength settings, reference levels, and. An optical power meter measures the strength of light traveling through a fiber optic cable, giving you a reading in dBm (decibels relative to one milliwatt). You measure optical power in dBm or insertion loss in dB. Consistent procedures ensure accuracy. Before using an optical. Step-by-step fiber optic cable testing guide using an optical power meter and VFL. Learn to measure loss, detect breaks, and certify links. Once it is on, set the wavelength of the light that.