What is photometry?
Photometry refers to all photometric measuring procedures in the wavelength of "visible light". These are converted by means of a photometer. Originally, photometry was a sub-area of physics. Today it is an engineering science.
Lighting technology uses a number of quantities to quantitatively represent the properties of light sources or their lighting effects. Quantities such as
Luminous intensity, Luminous flux, Luminanceand Illuminance
are used. These quantities describe visible light in terms of the physiological perception of brightness of the human eye. This distinguishes photometry from radiometry, which evaluates electromagnetic radiation only according to its physical power or energy.
