The effects of instrumental elliptical polarization on stellar point spread function fine structure

Abstract

We present a status report on a study on the effects of instrumental polarization on the fine structure of the stellar point spread function (PSF). These effects are important to understand because the the aberration caused by instrumental polarization on an otherwise diffraction-limited PSF will likely have have severe consequences for extreme high contrast imaging systems such as NASA's proposed Terrestrial Planet Finder (TPF) mission and the proposed NASA Eclipse mission. The report here, describing our efforts to examine these effects, includes two parts: 1) a numerical analysis of the effect of metallic reflection, with some polarization-specific retardation, on a spherical wavefront; 2) an experimental approach for observing this effect, along with a status report on preliminary laboratory results. The numerical analysis indicates that the inclusion of polarization-specific phase effects (retardation) results in a point spread function (PSF) aberration more severe than the amplitude (reflectivity) effects previously recorded in the literature. Preliminary in-lab results are consistent with our numerical predictions.