Ray Tracing In Inhomogeneous Media

A gradient index capability has been implemented in CODE VTM, a comprehensive lens design and analysis program. The Sharma' algorithm is used for raytracing. This algorithm is very efficient for determining the position of a ray but is less efficient for calculating the optical path. A series expansion of the optical path integral was implemented which improves the convergence of the optical path calculation. The terms in this series can be used to determine an optimum step length for the numerical solution of the differential equation. Several types of gradients may be analyzed including radial, axial, spherical and combinations of these. Examples will be given.