Photon approach to diffraction, interference, optical coherence, and image formation

When a parallel beam of light illuminates an aperture, the uncertainty principles require associating probability amplitude to a photon at each point of the aperture. Superposition of the amplitudes at the observation point behind the aperture, determines the probability that the photon strikes the point. In this report, we show that this “photon approach” explains several optical concepts. The approach is applied to study the diffraction from a single slit, double slit, and transmission phase step. Then, we apply it to explain the diffraction from a bi-prism and a Michelson’s interferometer, and show that the photon approach to the appearance of the interference fringes is more reasonable than the wave approach. We deduce the coherence behavior of light from the uncertainty principles, and finally, we use the photon approach to extract the ray optics laws and image formation formulae.