Interferometric connection of large ground-based telescopes

Abstract

Abstract. -In this article, we argue that the recent advent of two technological breakthroughs in the field of Optics, namely the development of Adaptive Optics and of infrared single-mode fibers, is likely to modify our conception of astronomical interferometry at optical wavelengths. In particular, it should become possible to realize the coherent combination of the giant telescopes that tend to cluster at the best ground-based astronomical sites. Although more limited in their scope than the dedicated interferometric systems, these potential arrays could achieve impressive performances in terms of sensitivity and angular resolution. As an example, we discuss in more details the case of a Mauna Kea cluster of large telescopes.

AGILIS: Agile Guided Interferometer for Longbaseline Imaging Synthesis

“…The 'Ohana Iki project, initially a pathfinder experiment for the development of the 'Ohana concept on Mauna Kea (Mariotti et al 1996), exemplified the convenience of using singe mode fibres in deploying flexible interferometric arrays. A description of this two-telescope experiment, a proof of technical feasibility, was followed by an outline of the key elements necessary to extend this idea to a larger array of telescopes: the AGILIS concept.…”

“…At a time when the development of adaptive optics (AO) on large telescopes was expected to improve the sensitivity of optical interferometers (Mariotti 1994), and the use of single-mode fibres in the beam combiner of an optical interferometer had just been demonstrated with the FLUOR instrument (Coudé du Foresto & Ridgway 1992;Perrin et al 1998), Mariotti et al (1996) proposed the 'OHANA (Optical Hawaiian Array for Nano-radian Astronomy) concept: turning the large AO-equipped telescopes on the summit of Mauna Kea into a sensitive optical interferometer using coherent beam transport with single-mode fibres. Around 2000, with the approval of the Mauna Kea telescopes' governing bodies, the 'OHANA concept moved towards implementation (Woillez et al 2001).…”

“…Whereas, Perrin et al (2006b) successfully demonstrated on-sky, long-distance coherent transport through single-mode fibres using the Keck Interferometer, the present paper moves a step further in reporting on the successful implementation and on-sky operation of an interferometer based entirely on single-mode fibres. These two milestones lead the way for Phase III : the construction of the full 'OHANA array envisioned by Mariotti et al (1996). For now, the realization of this vision remains beyond the resources of our current team supported by the observatories of Mauna Kea.…”

“…In the original 'OHANA concept (Mariotti et al 1996), this function separation is used to easily convert, with no significant infrastructure modification, the already available telescopes on Mauna Kea into an interferometer.…”

'OHANA phase II: a prototype demonstrator of fiber-linked interferometry between very large telescopes

“…The idea was first published by Mariotti et al (1996) 1 . The project started in 2000 and has been described in its current version in Perrin et al (2000) 2 .…”