Ray tracing in graded-index medium
Ray path in graded-index medium is curved and can be solved numerically by using eikonal equation, which is the starting point of geometrical optics. In this report, derivation of eikonal equation, the relation between eikonal equation and Fermat¡¯s principle is shown. Moreover, general ray equation for graded-index medium is derived from eikonal equation. Then, ray path can be realized more efficiently and accurately by solving the ray equation with Runge-Kutta method.