In the field of optics, dispersion is shorthand for chromatic dispersion and refers to the way that light, under certain conditions, separates into its component wavelengths and the colours corresponding with each wavelength become visible to a human observer.
- Chromatic dispersion refers to dispersion according to colour.
- Chromatic dispersion is the result of the relationship between wavelength and refractive index.
- When light propagates from one medium (such as air) to another (such as glass or water) every wavelength of light is affected to a different degree according to the refractive index of the media concerned. As a result, each wavelength changes direction by a different degree. In the case of white light, the separate wavelengths fan out with red on one side and violet on the other.
- A familiar example of chromatic dispersion is when white light strikes raindrops and a rainbow of colours become visible to an observer.
- As light first enters and then exits each raindrop, it separates into its component wavelengths which the observer perceives as distinctly separate colours.
- Remember that wavelength is a property of electromagnetic radiation, whilst colour is a feature of visual perception.
https://en.wikipedia.org/wiki/Dispersion_(optics)