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Proceedings Paper

New method for evaluating high-quality fog protective coatings
Author(s): Grzegorz Czeremuszkin; Mohamed Latreche; Guillermo Mendoza-Suarez
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Paper Abstract

Fogging is commonly observed when humid-warm air contacts the cold surface of a transparent substrate, i.e. eyewear lenses, making the observed image blurred and hazy. To protect from fogging, the lens inner surfaces are protected with Anti-Fog coatings, which render them hydrophilic and induce water vapor condensation as a smooth, thin and invisible film, which uniformly flows down on the lens as the condensation progresses. Coatings differ in protection level, aging kinetics, and susceptibility to contamination. Some perform acceptably in limited conditions, beyond which the condensing water film becomes unstable, nonuniform, and scatters light or shows refractory distortions, both affecting the observed image. Quantifying the performance of Anti-Fog coated lenses is difficult: they may not show classical fogging and the existing testing methods, based on fog detection, are therefore inapplicable. The presented method for evaluating and quantifying AF properties is based on characterizing light scattering on lenses exposed to controlled humidity and temperature. Changes in intensity of laser light scattered at low angles (1, 2 4 and 8 degrees), observed during condensation of water on lenses, provide information on the swelling of Anti-Fog coatings, formation of uniform water film, going from an unstable to a steady state, and on the coalescence of discontinuous films. Real time observations/measurements allow for better understanding of factors controlling fogging and fog preventing phenomena. The method is especially useful in the development of new coatings for military-, sport-, and industrial protective eyewear as well as for medical and automotive applications. It allows for differentiating between coatings showing acceptable, good, and excellent performance.

Paper Details

Date Published: 27 May 2011
PDF: 9 pages
Proc. SPIE 8082, Optical Measurement Systems for Industrial Inspection VII, 808239 (27 May 2011); doi: 10.1117/12.889541
Show Author Affiliations
Grzegorz Czeremuszkin, Revision Military Inc. (Canada)
Mohamed Latreche, Revision Military Inc. (Canada)
Guillermo Mendoza-Suarez, Revision Military Inc. (Canada)

Published in SPIE Proceedings Vol. 8082:
Optical Measurement Systems for Industrial Inspection VII
Peter H. Lehmann; Wolfgang Osten; Kay Gastinger, Editor(s)

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