A Broadband Scalar Vortex Coronagraph

Abstract

Broadband coronagraphy with deep nulling and small inner working angle has the potential of delivering images and spectra of exoplanets and other faint objects. In recent years, many coronagraphic schemes have been proposed, the most promising being the optical vortex phase mask coronagraphs. In this paper, a new scheme of broadband optical scalar vortex coronagraph is proposed and characterized experimentally in the laboratory. Our setup employs a pair of computer generated phase gratings (one of them containing a singularity) to control the chromatic dispersion of phase plates and achieves a constant peak-to-peak attenuation below $1\cdot 10^{-3}$ over a bandwidth of 120 nm centered at 700 nm. An inner working angle of ~λ/D is demonstrated along with a raw contrast of 11.5 magnitudes at 2λ/D.

Accepted, 6 pages, 6 images

References in corpus (2)

• Direct Imaging of Multiple Planets Orbiting the Star HR 8799
• Optical vortex coronagraphs on ground-based telescopes

Cited by in corpus (6)

• Ring-apodized vortex coronagraphs for obscured telescopes. I. Transmissive ring apodizers
• Astrophotonics: astronomy and modern optics
• Scalar vortex coronagraph mask design and predicted performance
• Vortex-phase filtering technique for extracting spatial information from unresolved sources
• Vortex fiber nulling for exoplanet observations: conceptual design, theoretical performance, and initial scientific yield predictions
• A broadband scalar optical vortex coronagraph