The OPM-3034B and OPM-3034C series handheld power meters were designed for optical power measurements at wavelength range from 800 to 1650nm. The power peters were calibrated at four frequently used wavelength: 850nm, 980nm, 1310nm, and 1550nm, ideal for both single and multi-mode fiber systems testing. The optical power measurement results could be displayed in linear (mW), logarithmic (dBm), and relative power (dB) modes. The user can choose one of these modes for absolute power or relative loss measurements.