A variety of interesting polarization effects can be observed using a parallel-face window placed under symmetric
stress of order <i>m</i> = 3 and illuminated with polarized light. Such windows, when placed under sufficient stress,
can produce rings of alternating vortex and non-vortex fields. When light is brought to a focus, one component of
circular polarization forms two nearly diffraction limited focal spots with axial separation larger than the usual
depth of focus. We analyze and experimentally test these phenomena using interferometric methods as well as a
Strehl ratio model and conclude by discussing applications to optical imaging.
A reversed-wavefront Young interferometer has recently been proposed and demonstrated for a direct measurement
of optical coherence. It relies on the creation of a reversed-wavefront replica of an electromagnetic
beam in such a way that the coherence function of the initial beam can be mapped out by simple translation
of a pair of pinholes in a Young's interference experiment. The same interferometer can, in principle, be used
for polarization-dependent coherence measurements, but presents significant challenges. In this paper, we will
describe the calibration of the interferometer and show measurements of the polarization-dependent coherence
function of two optical sources.