Each electronic energy meter must have at least one optical test output. Commonly its named with flashing pulse diode or similar. Other general purpose light power measuring devices are usually called radiometers, photometers, laser power. An optical power meter measures the photon energy in the form of current or voltage from an optical detector such as a semiconductor, a thermopile, or a pyroelectric detector. To augment the absolute power measurements NIST provides nonlinearity, spectral responsivity, and uniformity measurements.
