Toward visible wavelength coherent imaging with the LBT

The Large Binocular Telescope with its integrated adaptive optics systems and the LBTI beamcombiner provides a good platform for carrying out coherent imagin across its 22.7 m baseline. The first cameras used with LBTI have focused on infrared wavelengths. We describe a concept, called the LBT Interferometer Visible Extension (LIVE) to carry out coherent imaging with the LBT at visible wavelengths. LIVE will be able to create images of some of the stars with the largest angular diameters, map the surface of solar system moons, and provide detailed imaging of the inner scattered light regions of protoplanetary and transition disks. An initial approach can use the beamcombiner with its existing infrared phase sensor to carry out coherent imaging using frame selection to improve the image quality. Refined and more versatile phase sensing and correction can be implemented in a second stage to enable observations of a wider range of targets. LIVE will work both as a coherent imager, as well as a flexible dual aperture AO imager where simultaneous differential measurements can be made through independent use of each arm. We describe the science case and technical description below. We plan to develop the system with a flexible approach that allows increasingly complex modes of observation to be added once the basic performance is demonstrated.