Thickness and Slope Measurements of Thin
liquid Film
To an Accuracy of 
/4 Using Fizeau Interferomerty
Proceedings of PSFVIP-2,
May 16-19, 1999, Honolulu, USA
K. D. Kihm and David M. Pratt
This
paper presents a new optical technique to measure thin liquid film
thickness and slope based on the principle of Fizeau interferometry.
The interferometric fringes, constructed by the two reflected rays
respectively from the solid-liquid and liquid-vapor interface, allow
measurement of the thin film thickness at an accuracy of 
/4 when a monochromatic light source (
= 520 nm) is used. When a white light source is used, colored interferometric
fringes are formed and their color spectrum is constructed in different
orders depending on the slope if film thickness, i.e., the spectrum
order in R-Y-G-B indicates a negative slope of the film thickness
and the order in R-Y-G-B indicates a positive slope of the thickness.
Alse, a micro-scale extension and movement control of the thin film
region, using an electrohydrodynamic (EHD) phoresis, is first demonstrated
and visualied.
THICKNESS
AND SLOPE MEASUREMENTS OF EVAPORATIVE THIN LIQUID FILM
Journal
of Heat Transfer Gallery, AUGUST 1999, Vol. 121
Kenneth D. Kihm and David M. Pratt
The fizeau interferometric fringes,
constructed by the two reflected rays respectively from the solid-liquid
and liquid-vapor interfaces, allow measurement of the evaporative
thin film thickness at an accuracy of 
/4n for liquid of refractive index n when a monochromatic light source of
A is used (Karthikeyan et al., 1998). When a white light source
is used, rainbow-like interferometric fringes are formed and their
color spectrum is constructed in different orders depending on the
slope of film thickness: R-Y-G-B for thinning film and R-B-G-Y for
thickening film.