How often should an optical power meter be calibrated? Annual calibration is the standard. ISO 9001 systems and most acceptance test contracts require 12-month intervals. Heavy field use, drops, or extreme conditions warrant earlier. 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). To augment the absolute power measurements NIST provides nonlinearity, spectral responsivity, and uniformity measurements. Included with the RP450 is a calibration certificate, and free recalibration within 2 years of the date of purchase. To start the RMA process simply e European Economic Area (EEA).