A ray-tracing algorithm based on the computation of (Exact) ray paths with bidirectional ray-tracing

A novel ray-tracing algorithm to cope with the phase errors due to incorrect ray path computations in ray-launching approaches is presented. The algorithm utilizes bidirectional ray-tracing to collect information about wavefronts incident on an interaction surface and yields considerable improvements in accuracy compared to conventional unidirectional ray-tracing. The points, where exact ray paths intersect with the surface, are obtained according to the Fermat principle of least time. If the interaction surface is aligned with diffraction edges, the corresponding critical points of the second kind can also be retrieved and complicated diffraction treatments by shooting diffracted rays on Keller cones can be avoided. Thus, a substantial reduction in the number of rays can be achieved. Furthermore, a typical problem encountered in traditional ray-tracing due to the reception sphere mechanism, i.e., incorrect ray contributions, can mostly be evaded. Numerical results demonstrate the capabilities of the new algorithm and its advantages against traditional techniques.