In even the cleanest of environments, surfaces in optical systems are susceptible to the collection of dust. Because scattering from such contaminants can interfere with the intended operation of the system, it is important to consider their effects during the design via modeling and simulation. A standard developed by the Institute of Environmental Sciences and Technology (IEST) is most commonly used to define the typical sizes and density of particulates on a surface, which can then be used to create a BSDF profile of the contaminated surface. This BSDF profile can be applied to the smooth surfaces within a model to simulate the effects of the contaminants, making up a critical part of the stray light analysis for an optical system. The limitation of such an approach, however, is that the scattering events occur stochastically, with no spatial consistency. In this work a modeling approach is examined that considers the particulates to be stationary on the surface which is more realistic. With the particulates stationary, it is possible to isolate the effects of an individual particle, which can be especially useful for small scale systems. A variety of application designs are investigated through the use of computer simulation to demonstrate the advantages of the isolated contamination scattering approach.
|