title: Common-path achromatic interferometer-coronagraph: images from a breadboard demonstrator.
abstract: A three-dimensional common-path interferometer is proposed, which can achromatically null out an on-axis source while maintaining the detectability of an off-axis source. A geometric phase in the three-dimensional interferometer introduces an achromatic pi-phase shift to the light from the on-axis source, such that destructive interference nulls out the axial light at one of the ports of the interferometer. Light from the off-axis source, which is exempt from destructive interference, comes out from both ports with equal intensity. The common-path scheme makes the system highly immune to environmental disturbances. In the described experiment, a 6x10(-6) peak-to-peak nulling contrast was obtained.
authors: National Astronomical Observatory of Japan, Tokyo, Japan. alxandtv@cc.nao.ac.jp
authors: Alexander V
authors: AV
authors: Tavrov
authors: Jun
authors: J
authors: Nishikawa
authors: Motohide
authors: M
authors: Tamura
authors: Lyu
authors: L
authors: Abe
authors: Kaito
authors: K
authors: Yokochi
authors: Takashi
authors: T
authors: Kurokawa
authors: Mitsuo
authors: M
authors: Takeda