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

collaborations. Moreover, part of our work in this field is done within large networks such as ANR-funded or
OPTICON JRA collaborations.
12.3.1 Instrument support technology
Fast detectors for wavefront sensing: the JRA2 of Opticon Visible detectors fully matching the
requirements of Adaptive Optics wavefront sensors for 10-m class telescopes do not yet exist: current detectors
have frame rates which are too slow and which are too noisy for the second generation of AO systems. The
visible detectors developed by the JRA2 will be dedicated to AO applications. The scalability of these detectors
for ELT AO systems will be taken into account. The participants will attempt to define, manufacture and fully
characterize the best possible detector working at visible wavelengths which is suitable for wavefront sensors in
Adaptive Optics (AO) systems. This Joint Research Activity is closely linked to the Opticon JRA1-Adaptive
Optics. This will ensure that this detector development follows the AO requirements in terms of wavefront
sensing detectors. The detector format will be 240x240 pixels, the frame rate will be very fast (up to 2 kHz)
while the readout noise will be kept extremely low (typically below 1 e − ) by using the Electron Multiplying
technique developed by e2v Technologies, known as L3Vision. The following list of tasks concerns the LAOG
participation to theJRA2:
• Responsibility of the JRA: management of the activity, general meetings, report to the European Community,
reports and Opticon meetings.
• Responsibility of the cryogenic system: mechanical design of the cold head, cryogenic design, thermal
modeling of the whole camera, integration and cryogenic tests.
The OPTICON JRA2 being scheduled for 4 years, should continue during the next ”quadrennial contract”,
implying some continuing responsibility especially at the direction of the JRA2. As for AO components development,
this programme is likely to be proposed for a continuation during FP7. LAOG will have, in the two
next years, to express its will to keep involved in the organization of such a network and in its actual role herein.
The present day role came from the experience acquired with the NAOS visible wavefront sensor and anterior
expertise in different types of detectors (thermal IR, near IR and supraconducting devices). LAOG wishes to
keep this expertise and/or develop it further.
12.3.2 R&D activities
The future: a Lippmann spectral detector ? Following to the Lippmann color photography invention at
the end of the 19th century, we propose to renew the idea of stationary waves detection in the third dimension.
Until now, using electronic detectors rather than photographic emulsions was not possible because of their
too large size compared to the dimension required by standing waves sampling, typically one fourth of the
wavelength (i.e. about 100 nm for visible light). Recently E. le Coarer has proposed to perform this detection
in the evanescent field of optical waveguides using superconducting detectors (SSPD) developed by the CEA-
Grenoble/DRFMC. If successful, this still very prospective development would pave the way for a new generation
of ultra small spectrographs that should still have the same efficiency as all other spectral systems known
until now. It would also allow to build spectrograph mosaics rather than bulky 3D spectrographs that are
conventionally developed.
Detectors of this kind would have numerous applications in all fields where very fast spectroscopy is required like
telecommunications, cryptography and medicine. This is the reason why UJF has taken a patent on this topic.
In mid-2006, the studies that already started will show whether the development can be further undertaken.
LAOG will then have to analyze which objective is realistic and to decide what actual effort can be invested
into this direction.
12.3.3 Means and methods
The need for rather large collaborations is especially true for the Lippmann detector development. In the
continuity with successful collaborations with CEA-DRFMC, CRTBT, IMEP and IRAM, and in the context of
the MINALOGIC facilities, at least two new emerging collaborations can be cited to this end:
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