Finite element ray tracing: a new method for ray tracing in gradient-index media.

I apply the principle of finite elements, known in optics for calculating the beam propagation in waveguide structures, for calculation of meridional rays in inhomogeneous media. The plane is divided into finite elements that have a constant refractive index. The ray trajectory is calculated by a simple algorithm. Contrary to the existing methods, the model I propose in this research does not require an explicit formula for the index distribution. Only the numerical representation is sufficient, which can be a major advantage for calculation of the light propagation in real problems, such as the thermal lensing effect.