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 ela stohydrodynamic (EHD) film thickness and shape that incorporates an advance d experimental apparatus controlled by a computer with an extensive interfe rogram processing software. This software coordinates the data acquisition and instrument control and also provides real-time data processing and disp laying. Film thickness evaluation technique based on the colorimetric inter ferometry successfully overcomes limitations of conventional optical interf erometry). Colorimetric interferometry combining conventional chromatic int erferometry with image processing and differential colorimetry gives instan taneous detailed information on EHD film thickness and shape for various re gimes. This approach makes it possible to determine film thickness in the r ange of 1 to 800 nm with a resolution of about 1 nm.