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

Chapter 11
Results
11.1 Towards high dynamic with Adaptive Optics (AO)
The LAOG adaptive optics activity is actively contributing to the development of the current European efforts
to provide more efficient and performant adaptive optics (AO) systems for astronomy, but also for other applications,
such as ophthalmology, laser beam shaping, etc. In order to achieve these goals, LAOG is mainly acting
in two different directions, i/ the development of new components for the future generations of AO systems and
ii/ the contribution to the manufacture of AO instruments for ESO with other French and European partners.
11.1.1 The first generation: NAOS
The NACO instrument on the VLT UT-4 telescope consists of the NAOS adaptive optics system, providing
diffraction-limited images in the near infrared, and of its companion science camera, CONICA, equipped with a
1024 × 1024 ALLADIN detector covering the 1–5 µm spectral domain (Figure 11.1). CONICA was developed
under the responsibility of the Max-Planck Institute for Astronomy in Heidelberg. The main technical features
of NAOS are a piezo-stack deformable mirror with 185 actuators and a separate tip-tilt mirror, two selectable
Shack-Hartmann wavefront sensors operating either in the optical (450-950 nm) or in the near-IR (800-2500
nm) range, both featuring up to 14 × 14 sub-apertures. NAOS has been manufactured by a French consortium
including ONERA, Observatoire de Paris and LAOG. LAOG was in charge of the design and manufacturing of
the opto-mechanical structure (P. Rabou; E. Stadler), the instrument control system (J. Charton), the visible
wavefront sensor (P. Feautrier) and the integration and tests of the whole instrument in its static mode, i.e.
without the AO components 1 (P. Kern; P. Puget). LAOG was also responsible for the NAOS Science Group (A.-
M. Lagrange Project Scientist) and therefore LAOG scientific staff was heavily involved in the commissioning
activities 2 (J.-L. Beuzit, G. Chauvin, D. Mouillet - Figure 11.2). NAOS and CONICA are now widely used by
the ESO community amongst which several LAOG astronomers (cf. FOST).
11.1.2 The high contrast imaging: VLTPF
For its second generation instrumentation on the VLT, ESO has supported two 2-year concurrent Phase A
studies for a so-called ”Planet Finder” dedicated instrument, the first one led by the Max-Planck Institute for
Astronomy in Heidelberg and the second one led by LAOG (P.I. J.-L. Beuzit). The prime objective of such an
instrument for the VLT, initially proposed by LAOG (D. Mouillet) will be the discovery and study of new giant
extra-solar planets orbiting stars, by direct imaging of the circumstellar environment. The challenge consists
in the very large contrast between the host star and the planet, larger than ∼ 12.5 magnitudes at very small
1 Charton J., Hubert Z., Stadler E., Schartz W., Beuzit J.-L., 2003, System level simulation of micro-mirrors for adaptive optics
in Specialized Optical Developments in Astronomy. Atad-Ettedgui, E.; D’Odorico, S. Ed.. SPIE Proc., 4842, 207-218.
2 Mouillet D., Lagrange A. M., Beuzit J.-L., Moutou C., Saisse M., Ferrari M., Fusco T., Boccaletti A., 2004, Extra-solar Planets:
Today and Tomorrow in High Contrast Imaging from the Ground: VLT/Planet Finder; ASP Conf. Ser. 321, 39.
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