Parallel Ray Tracing Using the Message Passing Interface

Ray-tracing software is available for lens design and for general optical systems modeling. It tends to be designed to run on a single processor and can be very time consuming if the number of rays traced is large. Previously, multiple digital signal processors (DSPs) have been used to perform such simulations. This approach is attractive because DSPs are inexpensive, and the time saved through parallel processing can be significant. In this paper, we report a nearly linear relationship between the number of processors, and the rate of ray tracing with as many as 839 processors operating in parallel on the Naval Research Laboratory´s Cray XD-1 computer with the Message Passing Interface (MPI). In going from 1 to 839 processors, we achieved an efficiency of 97.9% and a normalized ray-tracing rate of in a system with 22 planar surfaces, two paraboloid reflectors, and one hyperboloid refractor. The need for a load-balancing software was obviated by the use of a prime number of processors.