Untitled - Laboratoire d'Astrophysique de l'Observatoire de Grenoble

the VLTI. CHARA is equipped with an imaging instrument, MIRC, fully compatible with LAOG integrated
optics beam combiners, which produced its first results in september 2005.
Extension to thermal IR Extension of current or programmed instruments such as VITRUV (see Section
12.2.1) to the medium-infrared (2 to 5 µm) is scientifically attractive. As such, this goal motivates R&D
activities aimed at developing IO components adapted to this wavelength range.
The ESA-funded contractual work IODA for development and characterization of IO components optimized
for the thermal IR (the range of interest for DARWIN), in collaboration with LETI/CEA and ALCATEL has
provided several potentially useful technological solutions. One of the key feature is to maintain the leakage
level to the very low level imposed by the DARWIN requirements. We now intend to continue this development
with the same partners in view of promoting an IO concept for the DARWIN nulling. LAOG would essentially
keep the same role (high level requirements definition and components characterization) with a possible
strengthening of the test phase on a nulling bench in the lab (which could be that of IAS).
MORE AMBITIOUS PROJECTS
Towards visible wavelengths ? A more open question is that of an evolution toward the widely desired
visible domain. Current limitations of the optical interferometers (absence of AO correction in V for instance)
has precluded ambitious moves into this direction and interferometry in the visible has remained limited to a few
experiences (REGAIN in France) operating generally in multi-modes. Because of the expected progress in AO
systems mentioned before and the technological possibilities, it seems reasonable to defend that using IO toward
the visible on a AO-corrected interferometer can now be projected in the new future. We may participate to
this evolution when a system study confirms that conditions are met.
ELT pupil masking and reconfiguration ? Through pupil masking and reconfiguration, diffraction-limited
resolution in V on a ELT may become possible before any AO system can be made operational, if ever. This
approach relies on the use of guided optics for the sub-pupils reconfiguration. A possible participation to such
a project undertaken at LESIA, could benefit from our simultaneous expertise in adaptive optics systems and
interferometric concepts at a system level. Our involvement will strongly depend on, obviously, the actual
collaboration possibilities and on the realism of access to an ELT for this particular science goal, at least during
the building phase of the primary mirror.
12.2.4 Means and methods
Manpower The IODA project lacks some resources that should be compensated by recruiting at a postdoctoral
level and also at a permanent position (a possibility being the University position opened in 2006). In
the mid-term, a technical position with a technological profile is necessary. The general needs for exploiting
imaging capabilities of VITRUV should be covered by a research position.
Locally, an increase of resources of the JMMC center of coordination will be necessary to fulfill its role within
the JMMC network of participating laboratories. The actual need, that depends not only on LAOG involvement
but of the whole network, is exposed in the JMMC report.
12.3 Cameras and detectors
Towards the ultimate photon detection, GRIL maintains a high level knowledge of photon detection (milimetric
wave bolometers, NIR and Visible) coupled or not to spectroscopy. The LAOG will continue to maintain an
expertise in this domain contributing to the R&D and the definition of detectors used by astronomy.
It is understandable that the astronomy community cannot afford to make alone the R&D effort necessary to
progress in this matter. For this reason, GRIL takes benefit of the growing expertise in micro and nanotechnologies
in the site of Grenoble at large (e.g. with CEA, CNRS and INPG laboratories) to build dedicated
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