VISIBLE INTERFEROMETRIC COUPLING OF 2 TELESCOPES THROUGH SINGLE-MODE OPTICAL FIBERS

The diameter of large conventional astronomical telescopes is currentl y restricted to the range of eight to ten meters. With this limitation in mind, there is an emerging interest in various applications of opt ical interferometry which would allow the synthesis of apertures large r than can be realized using current mirror fabrication technologies. Interferometry allows the substitution of the separation between teles copes to determine the limiting resolution rather than the diffraction limited resolving power of the individual telescope aperture(s). The implementation of this process, however, requires solutions to a numbe r of difficult problems in the transport and recombination of optical wavefronts. The use of single mode (SM) optical fibers to transport an d recombine optical wavefronts in interferometers offers a number of a dvantages as compared to other, more established techniques, yet suffe rs from an inefficient coupling of the wavefront energy into the very narrow fiber cores. We present preliminary results of an experiment in which interferometric recombination of wavefronts from two telescopes using SM fibers was used to obtain white light fringes on the bright star Arcturus (alpha Bootis). Our experience leads us to believe that for many imaging applications the continued development of fiber based interferometry will yield significant resolution gains over the diffr action limited performance associated with conventional monolithic ape rture systems.