Inventor: Alexandre Rothen
How it began: Working with Karl Landsteiner to investigate the conditions under which an antigen will attach to an antibody on a monomolecular layer, Rothen needed a way to measure the thickness of these layers.
What it does: This optical instrument measures the change that takes place in the degree of polarization of light (ellipticity) reflected from a stainless steel slide coated with the films under investigation. The half-shadow principle refers to the differing polarizations, seen as intensities via a crossed polarizer, that are reflected from two parts of the slide, with and without the film. The ellipsometer measures the thickness of monomolecular films to fractions of an angstrom.
Impact on medical science: This incredibly sensitive method was much used in many fields of science aside from immunology. Today it is also a workhorse of electronic microcircuit manufacture.
References: Rothen, A. The ellipsometer, an apparatus to measure thicknesses of thin surface films. Review of Scientific Instruments 1945, 16:26-30.
Rothen, A. Immunological reactions between films of antigen and antibody molecules. Journal of Biological Chemistry 1946, 168:75-97.
Photo by Lubosh Stepanek
Alexandre Rothen, ellipsometer, Karl Landsteiner, monomolecular layer