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Proceedings Paper

Strategy for interferometry with the Large Binocular Telescope
Author(s): John M. Hill
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Paper Abstract

A summary of the scientific requirements and the optical design requirements for the Large Binocular Telescope (LBT, former Columbus Project) beam combining optics is presented. Our goal for LBT is to produce a phased focal plane combining the beams from two 8.408 m diameter primaries on a common mount (14.417 m center-center). This provides an interferometric baseline of 22.825 m (edge-edge). This combined focal plane should be phased, in-focus and unvignetted over a field covering most or all of the isoplanatic patch in the best seeing conditions. These field requirements should be met for wavelengths from 0.4 to 20 micrometers . This allows the observer to obtain the maximum amount of diffraction-limited imaging information around each reference source. The individual telescope images should be close to diffraction-limited over the isoplanatic patch in order to facilitate adaptive correction of the interferometric field. A minimum number of warm reflections and minimum obstruction of the beams should be used in order to reduce the emissivity. The two- shooter telescope will be uniquely powerful in the thermal infrared (based on the combination of interferometric baseline and single element diffraction limit). We will be discussing several related classes of beam combiners to evaluate design tradeoffs for LBT. An earlier design considered direct combination of the beams from two F/33 secondary mirrors with long back focal distance. We have also considered reimaging the F/15 Gregorian focal planes with a number of optical designs.

Paper Details

Date Published: 9 June 1994
PDF: 12 pages
Proc. SPIE 2200, Amplitude and Intensity Spatial Interferometry II, (9 June 1994); doi: 10.1117/12.177274
Show Author Affiliations
John M. Hill, Steward Observatory/Univ. of Arizona (United States)

Published in SPIE Proceedings Vol. 2200:
Amplitude and Intensity Spatial Interferometry II
James B. Breckinridge, Editor(s)

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