Total internal reflection without change of polarization using a right-angle prism with half-wavelength-thick optical interference coating

Monochromatic light, which is polarized in an arbitrary state, is totally internally reflected at angle of incidence phi=45 degrees without change of polarization by a right-angle prism of refractive index n(0)=1+1/root 2 =1.70711 (e.g., N-LAK8 Schott glass at wavelength lambda=706 nm), which is coated with a transparent thin film of refractive index n(1)=(1+1/root 2)(1/2)=1.30656 (e.g., vacuum-deposited fluoride material) and of metric thickness equal to half of the vacuum wavelength of incident light, d=lambda/2. The ambient medium of evanescent refraction is assumed to be vacuum, air, or an inert gas. Wavelength shifts of +/- 50 nm, or changes of the internal angle of incidence of +/- 1 degrees around 45 degrees, cause phase errors of only a few degrees. The reflected and incident polarization states are nearly identical in the presence of such small phase errors. (C) 2009 Optical Society of America