A Caltech Library Service

Longitudinal dispersion control for the Keck interferometer nuller

Koresko, Chris and Mennesson, Bertrand and Serabyn, Eugene and Colavita, Mark and Akeson, Rachel and Swain, Mark (2003) Longitudinal dispersion control for the Keck interferometer nuller. In: Interferometry for Optical Astronomy II. Proceedings of SPIE. No.4838. Society of Photo-optical Instrumentation Engineers (SPIE) , Bellingham, WA, pp. 625-635. ISBN 9780819446176.

[img] PDF - Published Version
See Usage Policy.


Use this Persistent URL to link to this item:


The control of longitudinal dispersion, which determines the position of the null fringe as a function of wavelength, is central to the problem of producing deep broadband interferometric nulls. The dispersion is the sum of terms due to environmental factors such as the dry-air and water-vapor atmospheric seeing, the unbalanced air column due to the unequal delay-line paths between the telescopes the combiner, and to the distance from the central fringe. The difference between an achromatic nuller and a normal constructive combiner operating at its first (chromatic) null can be thought of as an added longitudinal dispersion, which for the case of the Keck Interferometer is smaller than the environmental terms. We demonstrate that the sum of these effects can be adequately compensated by an appropriate thickness of ZnSe combined with an additional achromatic pathlength. The Keck Interferometer nulling combiners take advantage of this result. They are intrinsically constructive combiners made to produce achromatic nulls by inserting a ZnSe dispersion corrector into each of the four input beams. We describe the null fringe stabilization control algorithm and present calculations of the required loop bandwidth and precision. A potentially important advantage of the present approach is that the system will be able to function as either a destructive or constructive combiner, depending on the value of a single control-loop parameter (the target fringe phase).

Item Type:Book Section
Related URLs:
URLURL TypeDescription
Mennesson, Bertrand0000-0003-4205-4800
Akeson, Rachel0000-0001-9674-1564
Swain, Mark0000-0002-0919-4468
Additional Information:© 2003 Society of Photo-Optical Instrumentation Engineers (SPIE). Funding was provided by NASA through the Keck Interferometer and Terrestrial Planet Finder projects. The research presented here was conducted at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Subject Keywords:Interferometry, Astronomy, Dispersion
Series Name:Proceedings of SPIE
Issue or Number:4838
Record Number:CaltechAUTHORS:20180910-131322386
Persistent URL:
Official Citation:Christopher D. Koresko, Christopher D. Koresko, Bertrand P. Mennesson, Bertrand P. Mennesson, Eugene Serabyn, Eugene Serabyn, Mark Colavita, Mark Colavita, Rachel L. Akeson, Rachel L. Akeson, Mark R. Swain, Mark R. Swain, } "Longitudinal dispersion control for the Keck interferometer nuller", Proc. SPIE 4838, Interferometry for Optical Astronomy II, (21 February 2003); doi: 10.1117/12.458032;
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:89504
Deposited By: George Porter
Deposited On:10 Sep 2018 20:31
Last Modified:16 Nov 2021 00:35

Repository Staff Only: item control page