Optical power meter is used to measure the absolute optical power, or by a fiber optical power relative to the depletion of the instrument.In the optical fiber system, optical power measurement is the most basic, much like the multimeter electronics;In the optical fiber measurement, optical power meter is a commonly used table heavy load.By measuring the transmitting terminal machine or the absolute power of the optical network, an optical power meter can evaluate the performance of the light end equipment.Combinations of light power meter and stability of light source, is able to measure the connection loss, continuity test, and help to evaluate quality of fiber optic link transmission
(source:http://www.jilongfiber.com/news/optical-power-meter.html)