CD spectrometer

When we look at a CD we see colourful stripes in addition to our own image. The CD works like a spectrometer. The light beams deviate in the grooves like in the chromatic glasses.

Depending on the source of light, different colours can be seen. In sunlight or lamp light we see all the colours of the rainbow. But if you take a fluorescent energy-saving bulb or a mercury one the colours would be 'incomplete' and would depend on the gas inside the bulb.