MASSIVELY PARALLEL COMPUTATIONAL SIMULATIONS IN LIGHT-SCATTERING

The Connection Machine, a massively parallel SIMD computer of 64K processors, is being used to simulate optical scattering and absorption phenomenae where the scattering objects are much larger than the wavelength of the incident light. One processor of the Connection Machine is assigned to an individual incident ray. The processor tracks the ray through the object system noting the multiple reflections and refractions which occur. The results calculated are the vectors of the outgoing rays which are leaving the object system environment. As each of the interactions of each incident ray are independent of those of all other rays, 64K incident rays can be tracked at a time. The classic communication bottleneck between processors on SIMD machines is nonexistent in this case. Using a stochastic approach, a Monte Carlo technique is used whereby each ray is either reflected or refracted based on probabilities. The object is represented by a collection of small facets enabling almost any shaped object or objects to be modeled from any orientation. The limit on the complexity of the object system is limited only by the size of the host memory of the Connection Machine. The algorithm is such that it runs in linear time to the number of facets which are used to represent the system.