Subject of photometry (phos, ancient Greek: light) is the measurement of visible electromagnetic radiation, so that the results describe the reaction of the human eye to this radiation as exactly as possible. Thus the photometry imitates by measurement the perception of light by the human eye. Further information is given at the page “fundamentals”.

The following photometric units are realized at BEV:

quantity unit symbol
Luminous flux Lumen lm
Luminous intensity Candela cd
Illuminance Lux lx

Generally speaking, radiometry is the measurement of electromagnetic radiation. The properties of the human eye are not taken in consideration for the measurements in the visible range of the electromagnetic spectrum. The BEV offers the determination of the spectral transmission ratio of optical filters as radiometric measurement.