title: Common-path achromatic interferometer-coronagraph: nulling of polychromatic light.
abstract: A three-dimensional common-path interferometer is proposed, which can achromatically null out an on-axis source while it maintains 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 the pi-phase shift, comes out from both ports with equal intensity. The common-path scheme makes the system highly immune to environmental disturbances.
authors.affiliation: Tokyo University of Agriculture and Technology, 2-24-16, Nakamachi, Koganei-shi, Tokyo, Japan. tavrov@cc.tuat.ac.jp
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Tavrov
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Tatsutoshi
authors.initials: T
authors.lastname: Shioda
authors.forename: Yukitoshi
authors.initials: Y
authors.lastname: Otani
authors.forename: Takashi
authors.initials: T
authors.lastname: Kurokawa
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Takeda