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A Ground-Based Scope That Flexes For Better Focus

Posted by timothy on from the much-cheaper dept.

Steve0987 writes "EE Times Online has an interesting article on a deformable telescope mirror that the University of Arizona has built. It uses 336 magnetic coils to deform the 2 foot secondary mirror and change its shape to compensate for everything from wind blowing against the telescope to atmospheric aberations. It is purported to provide 3 times the resolution of the Hubble telescope. (And you don't have to go into space to fix it."

7 of 29 comments (clear)

  1. hubble is not obsolete yet by u19925 · · Score: 4, Informative

    b4 u think hst is obsolete, note that the adaptive optics can only compensate the waveform deformation in a very narrow field. this is good to study binary stars, quasars, galactic neclei etc which are essentially tiny dots in the sky. hst has no waveform deformation at all, so it can use wide field imaging with full resolution; something which is not yet possible with adaptive optics. also adaptive optics requires that either the object is very bright itself or it has some bright objects very close by. hst has no such limitations.

    1. Re:hubble is not obsolete yet by PD · · Score: 5, Insightful

      Plus, time on big scopes is limited and there's a huge demand. Even the Palomar 200 inch scope, with optics that aren't as good as what we'd make today, keeps a full schedule of research. And that thing has to be 70 years old or something close to that. Big research scopes never become obsolete in the sense that nobody wants to use them.

      --
      If tits were wings it'd be flying around.
    2. Re:hubble is not obsolete yet by suitti · · Score: 4, Informative
      One can make an artificial guide star with a laser. This has already been done. And, the article talks about it.

      6.5 meter main mirror, .64 secondary deformable mirror. This is a big scope. Polomar is 5 meters.

      They hope to image extrasolar planets, for example, to get spectra. HST has already gotten spectra for an extrasolar planet - even though it has not imaged such an object. Step one: get the spectra for the parent star, step two: get the spectra during a transit, step three: compare.

      I'm not sure why they think that a deformable secondary is better than AO afterwords.

      Adaptive Optics are available for the ameteur astronomer. For example, SBIG

      --
      -- Stephen.
    3. Re:hubble is not obsolete yet by Doctor+Fishboy · · Score: 4, Informative

      > I'm not sure why they think that a deformable secondary is better than AO afterwords.

      Two words: warm surfaces.

      All other AO systems have ~20 warm reflecting surfaces that add up to a high near-IR background, and this severely limits your view of the IR universe. This system adds no additional surfaces into the telescope, and so its IR background is much lower.

      Dr Fish

  2. Good, God. The feedback required. by robslimo · · Score: 5, Interesting

    Wow!

    As a person who's spent about 15 years working with closed-loop controls in computer systems, my mind boggles at the thought of the quantity and variety of feedback devices required to pull this off.

    Accelerometers and strain transducers for wind forces, ground vibration and thermal effects on structures at the very least (and multitudes of them, all calibrated with respect to their location, etc). What I'm really having trouble with is how they are managing the thermal and atmospheric compensations.

    OTOH, this is an acedemic project and the statement "we have the *potential* to get images that are three times sharper than the Hubble" (my emphesis added) from the article doesn't inspire great confidence in what they may *really* have.

    Anyway, I'm off to look for answers at this link to the Center for Astronomical Adaptive Optics at the University of Arizona, the folks doing this work.

  3. Reasons why this system is better... by Doctor+Fishboy · · Score: 4, Informative

    Heh, a /. article that covers something I worked on!

    > but it sure looks like they're making claims of being first when they aren't.

    This *is* a first because the deformable mirror *is* the secondary mirror, which all modern reflecting telescopes have nowadays.

    The Starfire Optical Range (SOR) telescope and all other adaptive optic (AO) systems use about 10 to 20 additional reflections between the sky and the detector to do the AO correction - it may be a 3.5 meter telescope, but it's more like a 1 meter telescope in light-gathering power after 20 bounces for light loss are taken into account. The SOR telescope was also optimised for taking high resolution picutres of fast moving objects in low earth orbit *think spy satellites*

    The other bonus is that the new system is *excellent* for taking near infra-red pictures of the night sky, and a lot of recent astronomy is driven by a need for a good AO system in this regime (about 1 to 10 microns).

    Dr Fish

  4. Re:Too bad... by Doctor+Fishboy · · Score: 4, Informative

    > Note: I'm a UofA Alum, but their screwup on that mirror deserves mention whenever they do something right...

    I'm trying to check my history, but wasn't the Hubble mirror made and tested at Perkin Elmer? I don't remember the U of A being involved with Hubble's mirror. It was an error in the test equipment at Elmer that led to the spherical aberration being put into the mirror...

    You may be thinking of the NICMOS camera, which the U of A was involved with, and that had a problem with cryogens boiling off too rapidly, but that was corrected a while ago...

    Dr Fish