These meters provide a precise and reliable method for quantifying the power level of light across various wavelengths, making them essential instruments in the testing and calibration of optical systems. An optical power meter consists of a sensor, a detector, and a display unit. The term "optical power meter" may sound generic, but in popular usage, it specifically implies a fiber optic power meter. Read more about our handheld. While optical power meters are the primary power measurement instrument, optical loss test sets (OLTSs) and optical time domain reflectometers (OTDRs) also measure power in testing loss. TIA standard test FOTP-95 covers the measurement of optical power.