An Automatic System for Real-Time Evaluation of EHD Film Thickness and Shape Based on the Colorimetric Interferometry

This paper presents an automatic system for the real-time evaluation of elastohydrodynamic (EHD) film thickness and shape that incorporates an advanced experimental apparatus controlled by a computer with an extensive interferogram processing software. This software coordinates the data acquisition and instrument control and also provides real-time data processing and displaying. Film thickness evaluation technique based on the colorimetric interferometry successfully overcomes limitations of conventional optical interferometry. Colorimetric interferometry combining conventional chromatic interferometry with image processing and differential colorimetry gives instantaneous detailed information on EHD film thickness and shape for various regimes. This approach makes it possible to determine film thickness in the range of 1 to 800 nm with a resolution of about 1 nm.