Polarization analysis for Terrestrial Planet Finder coronagraph designs

摘要

One of NASA's two planet-finding missions will be an optical coronagraph. Due to the stringent science requirements, i.e., detecting a planet that is more than a billion times fainter than its parent star, effects that normally do not enter into instrument design must now be considered. One such effect is polarization. This paper has several goals. First, we review scalar diffraction theory (PSFs and Strehl ratios) and extend it to include polarization. Second, we employ a systems-engineering approach to subdivide and categorize instrumental effects, ultimately concentrating on polarizing non-coronagraph components (mirrors). Third, we push the limits of Code-V commercial optical-engineering software to model the polarization behavior for on- and off- axis configurations, using protected-silver and bare-gold mirror coatings at four wavelengths. Last, we present a brief discussion of future tasks: easing polarization requirements, source polarization, and coronagraph masks and stops.