Imaging ellipsometry for the visualization of bio-molecular layers

Abstract

Imaging ellipsometry is presented as a visualization technique to study bio-molecular layers. The layers have become more and more attractive in materials science, especially layers with thickness similar to cellular layers and with physiological activities which are very important in molecular biology and medicine. Normally bio-molecular layers are very thin, with thickness of between sub-nanometer and several tens nanometer. They are transparent in the visible range of light, so that they are recognized as a phase object in physics. Imaging ellipsometry is non-destructive and exhibits a high sensitivity to phase transitions within thin layers. It is capable of imaging local variations in the optical properties such as thickness due to the presence of different surface concentrations of bio-molecule or different deposited molecules. Imaging ellipsometry is based on conventional ellipsometry with charge coupled device (CCD) technique. The images are captured with a computer with image processing technique. It has high sensitivity to thickness variation (resolution in the order of angstrom), and high sampling speed (25 pictures with more than 10/sup 5/ pixels per second).