Experimental evaluation of achromatic phase shifters for mid-infrared starlight suppression.
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.
Gappinger
Robert O
RO
Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena,California 91109, USA. Robert.O.Gappinger@jpl.nasa.gov
Diaz
Rosemary T
RT
Ksendzov
Alexander
A
Lawson
Peter R
PR
Lay
Oliver P
OP
Liewer
Kurt M
KM
Loya
Frank M
FM
Martin
Stefan R
SR
Serabyn
Eugene
E
Wallace
James K
JK
D000465:Algorithms; D016477:Artifacts; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013055:Spectrophotometry, Infrared / Q000379:methods*; D055609:Stars, Celestial