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Proceedings Paper

Measurement of wavefront phase delay and optical density in apodized coronagraphic mask materials
Author(s): Peter G. Halverson; Micheal Z. Ftaclas; Kunjithapatham Balasubramanian; Daniel J. Hoppe; Daniel W. Wilson
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Paper Abstract

The development of stellar coronagraphs for exoplanet detection requires apodized occulting masks to effectively remove the light from the central star while allowing planet light to propagate past. One possible implementation, a gray-scale mask, includes the placement of micron-scale neutral density light absorbing patterns using High Energy Beam Sensitive (HEBS) glass. A second implementation, binary masks, uses micron-scale diffractive/reflective patterns. Coronagraph performance will be influenced by wavefront phase shifts introduced by the masks, hence accurate characterization of the fundamental optical properties, namely optical density (OD), phase advance/delay and optical constants of the material is needed for occulter design, development and modeling. In this paper we describe an interferometric apparatus that measures wavefront phase advance/delay through grey-scale and binary masks as functions of wavelength and optical density, which is also measured. Results for HEBS gray-scale masks will be presented along with ellipsometric measurements of optical constants.

Paper Details

Date Published: 5 October 2005
PDF: 10 pages
Proc. SPIE 5905, Techniques and Instrumentation for Detection of Exoplanets II, 59051I (5 October 2005); doi: 10.1117/12.618530
Show Author Affiliations
Peter G. Halverson, Jet Propulsion Lab. (United States)
Micheal Z. Ftaclas, Jet Propulsion Lab. (United States)
Kunjithapatham Balasubramanian, Jet Propulsion Lab. (United States)
Daniel J. Hoppe, Jet Propulsion Lab. (United States)
Daniel W. Wilson, Jet Propulsion Lab. (United States)

Published in SPIE Proceedings Vol. 5905:
Techniques and Instrumentation for Detection of Exoplanets II
Daniel R. Coulter, Editor(s)

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