What fiber optic test equipment is required for calibration traceable to the National Institute of Standards Technology?

• A. Power meter
• B. OTDR
• C. Optical spectrum analyzer
• D. Light source

Answer: (A)

Calibration traceability to NIST means every measurement can be tied back to SI units through an unbroken chain of comparisons. In fiber optics, optical power is a fundamental quantity measured in watts, and a power meter with a calibrated sensor can be traced to a NIST-traceable optical watt standard. This makes the power meter the direct, reliable reference for establishing and maintaining traceable calibration of optical power measurements in the field or lab. Other instruments have important roles—an OTDR characterizes length and faults, an optical spectrum analyzer analyzes spectral content and requires its own calibrations, and a light source provides output but does not by itself establish traceability to the standard—so they are not the primary tool for achieving NIST-traceable calibration of power measurements.