Optical Power Meter ( OPM) is a device used to measure the energy in an optical signal.

A typical OPM device consists of a calibrated sensor, display and management units. The sensor primarily consists of photodiode which fit to measure appropriate range of wavelengths. On the display unit, measured optical power and the wave length being measured is displayed. Depending on the set measurement wave on power meter, measured power can vary due to the calibration of the device. Power meters are calibrated using a traceable calibration standard such as a NIST standard.

Sometimes optical power meters are combined with different optical devices such us Optical Light Sources ( OLS) and Visual Fault Locators ( VFL) .

Such combination allow optical network builders test their fibers with different wavelengths at the same time.