Optical Modeling for Particle Contamination and Surface Defects

Optical contamination and surface damage can significantly degrade image quality, increase stray light, and reduce system performance. This presentation examines practical methods for modeling particle contamination and surface defects within optical simulations using industry recognized cleanliness and surface quality standards.

Topics include the application of Mie scattering theory for dust and particulate contamination, the use of ABg scattering models as a representation of contamination induced scatter, and the relationship between ISO 14644 cleanroom classifications and contamination modeling. Techniques for representing surface contamination through particle distributions, BSDF-based scattering models, volumetric scattering, and explicit small particle geometry are discussed.

Surface damage modeling is addressed through scratch-dig specifications, including the use of normal maps, texture-based defects, and randomized 3D particle geometry to simulate lens scratches, digs, and other imperfections. Validation approaches, modeling tradeoffs, and application examples for imaging systems are also presented.

About the presenter
Noah Hamstra is a senior applications engineer at Synopsys supporting Ansys optical simulation tools, with a focus on non-sequential ray tracing and stray light analysis using Ansys Speos and optical design workflows in Zemax OpticStudio. He has progressed through multiple applications engineering roles supporting optical design, testing, and validation projects across industry, academia, and aerospace and defense organizations.

Hamstra studied optical engineering at the University of Arizona, where he built a strong foundation in optical system design and analysis, and he continues to focus on practical, predictive stray light modeling for complex imaging systems