Qualification de IONIC, instrument de recombinaison ...

tel-00010396, version 1 - 4 Oct 2005
Abstract
Optical and instrumental validation of IONIC, solution for the beam com-
bination of astronomical interferometers based on planar integrated optics.
Abstract : Astronomical interferometry is an instrumental solution that benefit today by
great developments in order to increase the angular resolution for astrophysical observations.
However, some difficulties remains in the case of large ground based teslescope arrays, in
particular the combination of an important number of telescopes. The work presented here
is based on the development of the technologies of integrated optics for the interferometric
combination of the telescope beams. I will show that this technology, first developed in the
telecommunication field, also responds to astronomical requirements, particularly in terms
of operation through wide wavelength ranges. Integrated optics give easy acces to spatial
filtering and photometric calibration, two functions that have proved their efficiency for in-
creasing the measurements quality.
After the description of astronomical interferometry and its specific instrumental needs, I
will present the general concept of planar integrated optics and the available functionalities.
The laboratory tests of different beam combiners have led to the identification of key points
for the realization of instruments based on this technology. The high contrast levels obtained
validate the use of these functions for our astronomical applications.
First on-sky fringes on the IOTA interferometer (Arizona, USA) with two telescopes have
led to astronomical measurements compatible with previously published results. Thanks to
the acquired experience, we have developed a second instrument combining three telescope
beams for closure phase measurements. This instrument, under test nowaday, will give access
to imaging thanks to the combination of visibilities and phases informations on the observed
astrophysical object.
Our development are now mature enough to emphasize the use of this technology for complex
instrumental projects. This way, integrated optics has been chosen in the study of technolo-
gical solutions for the IRSI-DARWIN spatial interferometer.
Key-words : Astronomical interferometry, planar integrated optics, single mode wave-
guides, beam combination, closure phase.