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  • Ultrafast Astronomical Camera
Jun 2009
GARCHING, Germany, June 22, 2009 – The next generation of instruments for ground-based telescopes took a leap forward with the development of a new ultrafast camera that can take 1500 finely exposed images per second even when observing extremely faint objects.

The first 240x240 pixel images with the world's fastest high precision faint light camera, dubbed the OCam, were obtained through a collaborative effort between European Southern Observatory (ESO) and three French laboratories from the French Centre National de la Recherche Scientifique/Institut National des Sciences de l'Univers (CNRS/INSU). Cameras such as this are key components of the next generation of adaptive optics instruments of Europe's ground-based astronomy flagship facility, the ESO Very Large Telescope (VLT).

OCam is the world’s fastest high precision faint light camera. Developed in Europe, the camera is highly sensitive and able to take 1500 images per second. OCam has been specially designed and built by a team of French engineers from LAM, LAOG and the OHP and uses the CCD220 detector developed by e2v technologies. The technology developed with OCam has been transferred to ESO for use with the second generation instruments of ESO’s Very Large Telescope.(Images: P. Balard/INSU-CNRS/ESO)

“The performance of this breakthrough camera is without an equivalent anywhere in the world. The camera will enable great leaps forward in many areas of the study of the Universe,” says Norbert Hubin, head of the Adaptive Optics department at ESO.

OCam will be part of the second-generation VLT instrument Sphere. To be installed in 2011, Sphere will take images of giant exoplanets orbiting nearby stars.

A fast camera such as this is needed as an essential component for the modern adaptive optics instruments used on the largest ground-based telescopes because telescopes on the ground suffer from the blurring effect induced by atmospheric turbulence. This turbulence causes the stars to twinkle in a way that delights poets, but frustrates astronomers, since it blurs the finest details of the images.

Adaptive optics techniques overcome this major drawback, so that ground-based telescopes can produce images that are as sharp as if taken from space. Adaptive optics is based on real-time corrections computed from images obtained by a special camera working at very high speeds – many hundreds of times each second. The new generation instruments require these corrections to be done at an even higher rate, more than one thousand times a second, and this is where OCam is essential. CCD220_OCam.jpg

The CCD220 detector at the core of the OCam camera has 240 x 240 pixels and has a readout noise ten times smaller than detectors in current use, making it ideal for the faint light camera systems to be used on the second generation of Very Large Telescope instruments. It was developed by the British manufacturer e2v technologies.

“The quality of the adaptive optics correction strongly depends on the speed of the camera and on its sensitivity,” says Philippe Feautrier from the LAOG, France, who coordinated the whole project. “But these are a priori contradictory requirements, as in general the faster a camera is, the less sensitive it is.”

This is why cameras normally used for very high frame-rate movies require extremely powerful illumination, which is of course not an option for astronomical cameras. OCam and its CCD220 detector, developed by the British manufacturer e2v technologies, solve this dilemma, by being not only the fastest available, but also very sensitive, making a significant jump in performance for such cameras.

Because of imperfect operation of any physical electronic devices, a CCD camera suffers from so-called readout noise. OCam has a readout noise ten times smaller than the detectors currently used on the VLT, making it much more sensitive and able to take pictures of the faintest of sources.

“Thanks to this technology, all the new generation instruments of ESO’s Very Large Telescope will be able to produce the best possible images, with an unequalled sharpness,” said Jean-Luc Gach, from the Laboratoire d’Astrophysique de Marseille, France, who led the team that built the camera.

“Plans are now underway to develop the adaptive optics detectors required for ESO’s planned 42-metre European Extremely Large Telescope, together with our research partners and the industry,” says Hubin.

Using sensitive detectors developed in the UK, with a control system developed in France, with German and Spanish participation, OCam is truly an outcome of a European collaboration that will be widely used and commercially produced.

For more information, visit:  

Also see the ESO video

The three French laboratories involved are the Laboratoire d’Astrophysique de Marseille (LAM/INSU/CNRS, Université de Provence; Observatoire Astronomique de Marseille Provence), the Laboratoire d’Astrophysique de Grenoble (LAOG/INSU/CNRS, Université Joseph Fourier; Observatoire des Sciences de l’Univers de Grenoble), and the Observatoire de Haute Provence (OHP/INSU/CNRS; Observatoire Astronomique de Marseille Provence).

adaptive optics
Optical components or assemblies whose performance is monitored and controlled so as to compensate for aberrations, static or dynamic perturbations such as thermal, mechanical and acoustical disturbances, or to adapt to changing conditions, needs or missions. The most familiar example is the "rubber mirror,'' whose surface shape, and thus reflective qualities, can be controlled by electromechanical means. See also active optics; phase conjugation.
atmospheric turbulence
Irregularities and disturbances in the atmosphere that are of particular interest because they induce random temporal and spatial phase and amplitude fluctuations that destroy the optical quality and the coherence properties of laser beams.
The technology of generating and harnessing light and other forms of radiant energy whose quantum unit is the photon. The science includes light emission, transmission, deflection, amplification and detection by optical components and instruments, lasers and other light sources, fiber optics, electro-optical instrumentation, related hardware and electronics, and sophisticated systems. The range of applications of photonics extends from energy generation to detection to communications and...
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