title: Experimental evaluation of achromatic phase shifters for mid-infrared starlight suppression.
abstract: Phase shifters are a key component of nulling interferometry, one of the potential routes to enabling the measurement of faint exoplanet spectra. Here, three different achromatic phase shifters are evaluated experimentally in the mid-infrared, where such nulling interferometers may someday operate. The methods evaluated include the use of dispersive glasses, a through-focus field inversion, and field reversals on reflection from antisymmetric flat-mirror periscopes. All three approaches yielded deep, broadband, mid-infrared nulls, but the deepest broadband nulls were obtained with the periscope architecture. In the periscope system, average null depths of 4x10(-5) were obtained with a 25% bandwidth, and 2x10(-5) with a 20% bandwidth, at a central wavelength of 9.5 mum. The best short term nulls at 20% bandwidth were approximately 9x10(-6), in line with error budget predictions and the limits of the current generation of hardware.
authors.affiliation: Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena,California 91109, USA. Robert.O.Gappinger@jpl.nasa.gov
authors.forename: Robert O
authors.initials: RO
authors.lastname: Gappinger
authors.forename: Rosemary T
authors.initials: RT
authors.lastname: Diaz
authors.forename: Alexander
authors.initials: A
authors.lastname: Ksendzov
authors.forename: Peter R
authors.initials: PR
authors.lastname: Lawson
authors.forename: Oliver P
authors.initials: OP
authors.lastname: Lay
authors.forename: Kurt M
authors.initials: KM
authors.lastname: Liewer
authors.forename: Frank M
authors.initials: FM
authors.lastname: Loya
authors.forename: Stefan R
authors.initials: SR
authors.lastname: Martin
authors.forename: Eugene
authors.initials: E
authors.lastname: Serabyn
authors.forename: James K
authors.initials: JK
authors.lastname: Wallace
mesh_terms: D000465:Algorithms; D016477:Artifacts; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013055:Spectrophotometry, Infrared / Q000379:methods*; D055609:Stars, Celestial