Most optical power meters require calibration every 12-24 months, though frequent use may necessitate more regular intervals. When encountering display issues, first check the power source and. EXFO can help save both time and costs with an automated calibration test system that is designed for the verification of power meters, attenuators, sources and optical time-domain reflectometers (OTDRs). Calibrations are primarily on these wavelengths. Due to the fact that this capability largely depends on the quality of the calibration process, it is important to carefully select your calibration provider. Keysight Technologies. NIST developed a testing system to provide absolute power calibrations for optical power meters.