Recently a real time particle deposition monitoring system is developed. After discussions with optical system engineers a new feature has been added. This enables the real time monitoring of obscuration of exposed optical components by counting the deposited particles and sizing the obscuration area of each particle. This way the Particle Obscuration Rate (POR) can be determined. The POR can be used to determine the risk of product contamination during exposure. The particle size distribution gives information on the type of potential particle sources. The deposition moments will indicate when these sources were present.
Koos Agricola, Koos Agricola,
"Real time obscuration monitoring", Proc. SPIE 9952, Systems Contamination: Prediction, Control, and Performance 2016, 99520L (27 September 2016); doi: 10.1117/12.2237260; https://doi.org/10.1117/12.2237260