This guide covers when to calibrate, what calibration actually involves, what a legitimate certificate looks like, and how to verify your meter's accuracy between calibrations. Send the meter to a NIST-traceable calibration lab. We explain the measurement standards, systems, methods, and uncertainties related to. An optical power meter is the most common type of test equipment used to support fiber optic system. These sources include laser diodes, light emitting diodes (LEDs) and fibre-type sources.