Fermat’s Principle

As mentioned in chapter 1, optics and mechanics have a number of analogies which have been used time and again to understand and appreciate concepts in either of the fields. One of the most basic analogy is between the Fermat’s principle in optics and the Hamilton’s principle of least action in classical mechanics [1]. As in classical mechanics, we can use either the Lagrangian or the Hamiltonian formulations to further study properties of light ray propagation. We will first develop the Lagrangian formulation which will be followed by the Hamiltonian formulation.