JRA2

1
JRA2 Fast Detectors for Adaptive Optics
The participants will attempt to define,
fabricate 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 JRA1 - Adaptive
Optics. This will ensure that this detector
development follows the AO requirements in terms
of wavefront sensing detectors. The detector
format should be 256x256 pixels, the frame rate
must be very fast (up to 2 kHz) while the readout
noise must be kept extremely low (typically below
3e-).
Detector technologies and specifications A
non-exhaustive list of possible detector
technologies is 1.Single direction or split
frame transfer CCD with a large number (up to
512) of output amplifiers that are read out at
moderate to low speed. A possible output
amplifier configuration is one amplifier per
detector column. 2.Single direction or split
frame transfer CCD with a small number of output
amplifiers that are read out at high speed. To
meet low read noise requirements, the devices
will use special techniques such as electron
multiplication CCD technology to amplify the
signal and reduce effective output amplifier read
noise. 3.Direct readout device (hybrid, CMOS)
where the detector will be coupled to a readout
multiplexer. A Call For Tender was started in
July 2004 in order to choose the detector
manufacturer. Now this choice has been made, the
detector is being fabricated and fully tested, at
first by the manufacturer and soon after by the
partners of the JRA2. The main output of the JRA2
will be the test report of the detector produced
in the context of AO systems for 10m class
telescopes
Fast Detector for AO the need The next
generation of Adaptive Optics systems for 8 to
10-m class telescopes will require an increased
number of degrees of freedom, which will increase
the number of actuators required typically by a
factor of 5 to 10. Existing CCDs will not allow
production of the corresponding wavefront
sensors. The success of such new AO concepts will
therefore strongly depend on new developments in
the field of visible wavefront sensor detectors,
both in terms of usable number of pixels and
increased sensitivity.

• Participants
• The 7 collaborating organisations are
• Laboratoire dAstrophysique de Grenoble
• Laboratoire dAstrophysique de Marseille
• Observatoire de Haute Provence
• Instituto de Astrofisica de Canarias
• ESO
• ONERA
• Observatoire Midi-Pyrénées

c/o ESO the NAOS visible wavefront sensor
Block diagram of a simple AO system
OPTICON is funded by the European Commission
under Contract RII3-CT-2004-001566