12 September 2012 Approaches for achieving broadband achromatic phase shifts for visible nulling coronagraphy
Author Affiliations +
Proceedings Volume 8445, Optical and Infrared Interferometry III; 84452C (2012); doi: 10.1117/12.926237
Event: SPIE Astronomical Telescopes + Instrumentation, 2012, Amsterdam, Netherlands
Abstract
Visible nulling coronagraphy is one of the few approaches to the direct detection and characterization of Jovian and Terrestrial exoplanets that works with segmented aperture telescopes. Jovian and Terrestrial planets require at least 10-9 and 10-10 image plane contrasts, respectively, within the spectral bandpass and thus require a nearly achromatic π-phase difference between the arms of the interferometer. An achromatic π-phase shift can be achieved by several techniques, including sequential angled thick glass plates of varying dispersive materials, distributed thin-film multilayer coatings, or techniques that leverage the polarization-dependent phase shift of total-internal reflections. Herein we describe two implementations of such techniques: sequential thick glass plates and Fresnel rhomb prisms. A viable technique must achieve the achromatic phase shift while simultaneously minimizing the intensity difference, chromatic beam spread and polarization variation between the interferometer arms. In this paper we describe the above implementations and report on the trades associated with each technique that will lead to an implementation of the most promising one in Goddard's Visible Nulling Coronagraph (VNC).
© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Matthew R. Bolcar, Richard G Lyon, "Approaches for achieving broadband achromatic phase shifts for visible nulling coronagraphy", Proc. SPIE 8445, Optical and Infrared Interferometry III, 84452C (12 September 2012); doi: 10.1117/12.926237; http://dx.doi.org/10.1117/12.926237
PROCEEDINGS
14 PAGES


SHARE
KEYWORDS
Phase shifts

Glasses

Prisms

Interferometers

Polarization

Reflection

Coronagraphy

Back to Top