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Catastrophe Optics Method to Determine the Micro-Nano Size Profiles at TPL of Liquid Films on a Solid SurfaceAs discovered by recent studies, what directly affects the wetting and spreading is curvature in micro-region rather than the macroscopic contact angle. Measuring the profile of the micro-region becomes an important research topic. Recently, catastrophe optics has been applied to this kind of measurements. Optical catastrophe occurring in far field of waves of liquid-refracted laser beam implies a wealth of information about the liquid spreading not only for liquid drops but also for films. When a parallel laser beam passes through a liquid film on a slide glass at three-phase-line (TPL), very interesting optical image patterns occur on a screen far from the film. An analysis based on catastrophe optics discloses and interprets the formation of these optical image patterns. The analysis reveals that the caustic line manifested as the bright-thick line on the screen implies the lowest hierarchy of optical catastrophes, called fold caustic. This optical catastrophe is produced by the inflexion line on liquid surface at the liquid foot, which is formed not only in the spreading of drops but also in spreading of films. The generalized catastrophe optics method enables to identify the edge profiles and determine the edge foot height of liquid films. Keywords: Crossover region, Inflexion line, liquid edge foot, Catastrophe optics, Caustic and diffraction
Document ID
20110016102
Document Type
Conference Paper
Authors
Chao, David F. (NASA Glenn Research Center Cleveland, OH, United States)
McQuillen, J. B. (NASA Glenn Research Center Cleveland, OH, United States)
Sankovic, J. M. (NASA Glenn Research Center Cleveland, OH, United States)
Zhang, Nengli (Ohio Aerospace Inst. Cleveland, OH, United States)
Date Acquired
August 25, 2013
Publication Date
December 18, 2009
Subject Category
Optics
Report/Patent Number
MNHT2009-18335
E-17973
Meeting Information
ASME 2009 2nd Micro/nanoscale Heat and Mass Transfer International Conference(Shanghai)
Funding Number(s)
WBS: WBS 138494.01.04.01
Distribution Limits
Public
Copyright
Other