With the help of a spectrometer, light can be measured directly or as reflected or transmitted light.
When measuring light directly, the different spectral compositions of different light sources can be easily visualised. For example, the spectral composition of light sources used in everyday life, such as incandescent lamps or halogen lamps, fluorescent tubes and LEDs, differ significantly from one another. The differences between warm and cold white light are also visible for each type of light source, sometimes with considerable effects on colour perception.
If the light reflected by surfaces or, in the case of transparent materials, the transmitted light is measured, the physical interaction of light and material can be visualised. Coloured surfaces or colour filters absorb the complementary portion of the light used. Accordingly, the surfaces or the transmitted light appear coloured.