Paraxial Ray Optics
Light is an electromagnetic wave and since electromagnetic waves are completely described by Maxwell’s equations, it seems possible, in principle, to obtain all the laws of propagation of light as solutions of Maxwell’s equations. This problem is, in general, difficult to solve and rigorous solutions may be obtained only for some simple systems.* Hence one is led to consider approximations that might give easily understood solutions and also describe the phenomenon well. One such approximation makes use of the fact that when the wavelength of light is extremely small compared to the dimensions of the system with which it interacts, one can, to a good approximation, neglect the finiteness of the wavelength. Indeed, the zerowavelength approximation of wave optics is known as geometrical optics.
KeywordsHomogeneous Medium Geometrical Optic Eikonal Equation Principal Plane Phase Front
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