title: Design and laboratory demonstration of an achromatic vector vortex coronagraph.
abstract: A vector vortex coronagraph (VVC) is one of promising means for imaging extremely faint objects around bright stars such as exoplanets. We present a design of an achromatic VVC, in which an axially-symmetric half-wave plate (AHP) is placed between crossed polarization filters (circular polarizer and analyzer). The circular polarizer and the analyzer are both composed of a polarizer and a quarter-wave plate (QWP). We demonstrate, via Jones calculus and Fourier analysis, that the achromatic stellar elimination can theoretically be realized by optimal polarization filters, even when chromatic AHP and QWPs are used. We carried out laboratory demonstrations of the designed VVC using a photonic-crystal AHP. As a result, we observed achromatic coronagraphic performance, a light suppression level of 7 × 10(-5), over a wavelength from 543 nm to 633 nm.
authors.affiliation: Division of Applied Physics, Faculty of Engineering, Hokkaido University, Kita-13, Nishi-8, Sapporo, Hokkaido 060-8628, Japan. nmurakami@eng.hokudai.ac.jp
authors.forename: Naoshi
authors.initials: N
authors.lastname: Murakami
authors.forename: Shoki
authors.initials: S
authors.lastname: Hamaguchi
authors.forename: Moritsugu
authors.initials: M
authors.lastname: Sakamoto
authors.forename: Ryohei
authors.initials: R
authors.lastname: Fukumoto
authors.forename: Akitoshi
authors.initials: A
authors.lastname: Ise
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Oka
authors.forename: Naoshi
authors.initials: N
authors.lastname: Baba
authors.forename: Motohide
authors.initials: M
authors.lastname: Tamura
mesh_terms: D003116:Color; D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007089:Image Enhancement / Q000295:instrumentation*; D012031:Refractometry / Q000295:instrumentation*; D061351:Telescopes