How to use Optical Power Meter and Optical Light Source

Optical Power Meter (OPM) is a device used to measure the optical power in an optical signal. The term usually refers to a device for testing average power in fiber optic systems.
Optical Light Source (OLS) is an apparatus that uses a diode laser or LED as a stabilized light emitter. It is used with Optical Power Meter that measures the power received, determining the attenuation of the optical fiber segment.