title: Two-dimensional thickness measurements based on internal reflection ellipsometry.
abstract: An imaging ellipsometer technique on internal reflection geometry that can measure the thickness distribution of a thin film possessing an assumed refractive index is described. Because a prism is used for the internal reflection geometry, it was theoretically predicted that angular derivation from the normal incidence on the prism surface affects only the psi value by a factor of 0.97 at maximum. Measurements were carried out for an optical system of silica substrate-TiO2 layer-silica layer-protein film-air, with a thin-film array of dried protein as the sample film. Thickness of the protein films was two-dimensionally estimated only from the measured map of the delta value by use of the simulated relationship between the thickness and the delta value. The thickness map obtained was coincident on the whole with the results according to a mechanical scanning. The detection limit was approximately +/- 0.2 nm. These findings validate the optical effect of a high-index additional layer to improve the sensitivity and precision of thickness measurements of the sample film on transparent substrates.
authors.affiliation: Single-Molecule Bioanalysis Laboratory, National Institute of Advanced Industrial Science and Technology (AIST), Hayashi-cho, Takamatsu 761-0395, Japan. otsuki-s@aist.go.jp
authors.forename: Soichi
authors.initials: S
authors.lastname: Otsuki
authors.forename: Kaoru
authors.initials: K
authors.lastname: Tamada
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Wakida
mesh_terms: D020099:Coated Materials, Biocompatible / Q000032:analysis / Q000737:chemistry*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007089:Image Enhancement / Q000295:instrumentation* / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008567:Membranes, Artificial; D011506:Proteins / Q000032:analysis / Q000737:chemistry* / Q000648:ultrastructure*; D012031:Refractometry / Q000295:instrumentation* / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013499:Surface Properties
chemical_list: D020099:Coated Materials, Biocompatible; D008567:Membranes, Artificial; D011506:Proteins