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Sharpest Images With "Lucky" Telescope
igny writes "Astronomers from the University of Cambridge and Caltech have developed a new camera that gives much more detailed pictures of stars and nebulae than even the Hubble Space Telescope, and does it from the ground. A new technique called 'Lucky imaging' has been used to diminish atmospheric noise in the visible range, creating the most detailed pictures of the sky in history."
One of the main limitations to ground-based optical telescopes (and one of the reasons that Hubble gets such amazing images) is that the atmosphere generates considerable distortion. Random fluctuations in the atmosphere cause images to be blurry (and cause stars to twinkle, of course). The technique they present appears to be taking images at very high-speed. They developed an algorithm that looks through the images, and identifies the ones that happen to not-blurry (hence "lucky"). By combining all the least blurry images (taken when the atmosphere just happened to be not introducing distortion), they can obtain clear images using ground-based telescopes (which are bigger than Hubble, obviously). I imagine the algorithm they've implemented tries to use sub-sections of images that are clear, to get as much data as possible.
Overall, a fairly clever technique. I wonder how this compares to adaptive optics, which is another solution to this problem. In adaptive optics, a guide laser beam is used to illuminate the atmosphere above the telescope. The measured distortion of the laser beam is used to distort the imaging mirror in the telescope (usually the mirror is segmented into a bunch of small independent sub-mirrors). The end result is that adaptive optics can essentially counter-act the atmospheric distortion, delivering crisp images from ground telescopes.
I would guess that adaptive optics produces better images (partly because it "keeps" all incident light, by refocusing it properly, rather than letting a large percentage of image acquisitions be "blurry" and eventually thrown away), but adaptive optics are no doubt expensive. The technique presented in TFA seems simple enough that it would be added to just about any telescope, increasing image quality at a sacrifice in acquisition time.
DIY.
DMCA, Hollings, Palladium. What might have sounded like paranoia is now common sense.
TFA mentions that they can achieve images better than Hubble. The sample image they show, of the Cat's Eye Nebula, isn't as sharp as the Hubble image of the same object.
Probably they can push their technique harder than this initial image suggests (it was mainly comparing the "lucky" image with a conventional, blurry, ground-based image)... But I just thought it would be good to show Hubble's pictures alongside.
Additionally, while they don't mention details in the article, I presume they have a specially designed camera.
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They are using a new kind of CCD that somehow lowers the noise floor. Details are at:
http://www.ast.cam.ac.uk/~optics/Lucky_Web_Site/L
In fact this site (same basic place) is much more informative than the press release and answers a lot of questions:
http://www.ast.cam.ac.uk/~optics/Lucky_Web_Site/i