'OHANA-Iki: a test-bed for the 'OHANA beam combiner and delay line at CFHT

Abstract

The possibility of interferometrically coupling large telescopes using single-mode (SM) fibers is a very attractive one, especially at topographically complex and culturally sensitive astronomical observing sites such as the Mauna-Kea summit in Hawaii. The 'OHANA project (Optical Hawaiian Array for Nanoradian Astronomy) aims to link up seven of the large telescopes on Mauna-Kea. The concept of using SM fiber links for interferometry has been demonstrated using the two W. M. Keck telescopes. A beam-combiner and optical delay line has been installed at the Canada France Hawaii Telescope (CFHT) to link up Gemini North and CFHT. In order to test the CFHT beam-combiner without making use of CFHT and Gemini observing time, the idea of using two small, 20 cm aperture telescopes to inject starlight into the 'Ohana interferometer fibers was devised. This project, dubbed 'OHANA-Iki, is also exploring the concept of a "soft" optical interferometer, specifically one in which the telescopes are easily movable and would not require the heavy, fixed infrastructure found in conventional freespace interferometers such as the VLTI.