Fundamental Principles of Holography

The behaviour of light can be modelled either as a propagating electromagnetic (e-m) wave or as a stream of massless particles known as photons . Although the models are seemingly contradictory both are necessary to fully describe the full gamut of light phenomena. Whichever model is most appropriate depends on the phenomenon to be described or the experiment under investigation. For example, interaction of light with the atomic structure of matter is best described by the photon model: the theory of photon behaviour and its interactions is known as quantum optics. The phenomenon of refraction, diffraction and interference, however, are best described in terms of the wave model i.e. classical electromagnetism.