Surface roughness and optical contact characterization of transparent prisms using frustrated total internal reflection tunneling ellipsometry

Optical tunneling of collimated monochromatic light of wavelength lambda through an air gap of thickness d(x, y) between two stress-free transparent prisms of the same refractive index N at an angle of incidence phi > the critical angle is accompanied by spatially variable transmission differential phase shift Delta(t)(x, y) that can be measured by a straight-through imaging ellipsometer with suitable polarizing and analyzing optics and two-dimensional array detector. Operation under the condition of equal tunneling for the p and s polarizations at phi(e) = arcsin root 2/(N-2 +1) leads to an analytical solution for d(x, y) in terms of Delta(t)(x, y). (C) 2014 Elsevier B.V. All rights reserved.