Interferometry on the large binocular telescope

The Large Binocular Telescope (LBT) will be a unique interferometric facility when it is completed in 2005. The telescope incorporates two, 8. 4-meter diameter primary mirrors on a single mounting. With 14.4 meter center-to-center spacing, this interferometer provides the equivalent collecting area of a 12-meter telescope, and, depending on the beam combination scheme, the spatial resolution of a 14.4 or 22.8-meter telescope. We report on the status of two initial interferometric instruments planned for the LBT. A group based at the University of Arizona is constructing LBTI, a thermal infrared beam combiner focusing on nulling, but allowing thermal imaging as well. This instrument will search for and measure zodiacal light in candidate stellar systems in preparation for the Terrestrial Planet Finder (TPF) and Darwin missions. There is also a program to search for young Jupiters. A second group, based in Heidelberg, Arcetri, Cologne, and Bonn, is building LINC-NIRVANA, a near-infrared Fizeau-mode beam combiner with multi-conjugated adaptive optics (MCAO). Fizeau interferometry preserves phase information and allows true imagery over a wide field of view. Using state-of-the-art detector arrays, coupled with advanced atmospheric correction strategies, LINC-NIRVANA will enable a broad variety of scientific programs that require the ultimate in sensitivity, field-of-view, and spatial resolution.