title: Study of a coronagraphic mask using evanescent waves.
abstract: The evanescent wave coronagraph (EvWaCo) is a specific kind of band-limited coronagraph using the frustrated total internal reflection phenomenon to produce the coronagraphic effect (removing starlight from the image plane in order to make the stellar environment detectable). In this paper, we present a theoretical and experimental study of the EvWaCo coronagraphic mask. First, we calculate the theoretical transmission and we show that this mask is partially achromatic. Then, we present the experimental results obtained in unpolarized light at the wavelength λ≈900 nm and relative spectral bandwidth Δλ/λ≈6%. In particular, we show that the coronagraph provides a contrast down to a few 10-6at an angular distance of about ten Airy radii.
authors.forename: Christophe
authors.initials: C
authors.lastname: Buisset
authors.forename: Yves
authors.initials: Y
authors.lastname: Rabbia
authors.forename: Thierry
authors.initials: T
authors.lastname: Lepine
authors.forename: Mary-Angelie
authors.initials: MA
authors.lastname: Alagao
authors.forename: Elsa
authors.initials: E
authors.lastname: Ducrot
authors.forename: Saran
authors.initials: S
authors.lastname: Poshyachinda
authors.forename: Boonrucksar
authors.initials: B
authors.lastname: Soonthornthum