FM8515B handheld optical-power meter measures optical-system power and attenuation. The unit is calibrated at 850, 1310 and 1550 nm, but can also be used from 800 to 1700 nm. Dynamic range is +5 to -60 dBm. It operates continuously on a 9V power supply for up to 20 hours. When used with dual optical sources, the unit characterizes and troubleshoots optical-fiber systems.