To use a power meter for fiber optic testing, always clean connectors first with lint-free wipes or click-to-clean tools. Select the correct wavelength and set your reference. You measure optical power in dBm or insertion loss in dB. Consistent procedures ensure accuracy. Learn to measure loss, detect breaks, and certify links. For day-to-day installation and maintenance, an optical power meter and a VFL are the two. Fiber loss is the difference between the power when light is coupled from the transmitting end to the fiber and the power when the light reaches the receiving end.