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  1. #1
    rander3127's Avatar
    rander3127 Guest

    Default New telescope design



    A company called, fsona.com has designed a Cassegrain style telescope
    that integrates the secondary mirror into the face of the primary.
    The traditional position of the secondary mirror in the telescope
    taken up by a flat mirror instead. The light is double-reflected.
    The result is a telescope 2/3 the typical length for a Cassegrain
    design, plus alignment tolerances are much lower because the curved
    "secondary" is contained on the surface of the primary.
    This story is in the current issue of "Photonics Spectra" magazine.


  2. #2
    Shawn's Avatar
    Shawn Guest

    Default New telescope design

    rander3127 wrote:
    From the A picture's worth a thousand words department:
    http://www.photonics.com/spectra/con...P/QX/index.htm
    Interesting.
    How hard to grind/polish?
    I wonder what sort of interference/noise/scatter arises from the
    junction of the two figures on the primary?

    Shawn

  3. #3
    Chris L Peterson's Avatar
    Chris L Peterson Guest

    Default New telescope design

    On Fri, 01 Oct 2004 22:11:15 -0400, rander3127 <rander3127@rogers.com> wrote:


    Cute, but I think their primary application is for very long wavelengths (IR to
    terahertz) for their communications products. They are using diamond turned
    optics. If you had to make one of these things for imaging use at visual
    wavelengths, I think the grinding and polishing costs would be very high. If it
    is used for imaging, it will be for very specialized applications where cost
    doesn't matter much (military and space, probably).

    _________________________________________________

    Chris L Peterson
    Cloudbait Observatory
    http://www.cloudbait.com

  4. #4
    Clif's Avatar
    Clif Guest

    Default New telescope design

    Chris L Peterson <clp@alumni.caltech.edu> wrote in message news:
    This is a specialized "light bucket". Lots of central obstruction,
    and no good way to reduce it. Not practical for the ATM who doesn't
    generally have access to diamond turned optics. Could be made with a
    separate piece of glass for the secondary mounted in the hole of the
    primary, but no good reason to keep it there. Much better places to
    put a secondary mirror.

    Clif

  5. #5
    Doug Peterson's Avatar
    Doug Peterson Guest

    Default New telescope design

    At least in principle the CC tertiary mirror could be inserted into a
    hole through the primary the way many rumak type maksutovs are
    constructed. Baffling would be interesting and may be the real
    limitation here. It looks like it would yield an erect image.

  6. #6
    Chris L Peterson's Avatar
    Chris L Peterson Guest

    Default New telescope design

    On 2 Oct 2004 10:16:13 -0700, dougspeterson@prodigy.net (Doug Peterson) wrote:


    This would seem to be an imaging scope only, not visual, given the massive CO
    required by the design.

    _________________________________________________

    Chris L Peterson
    Cloudbait Observatory
    http://www.cloudbait.com

  7. #7
    vic20owner's Avatar
    vic20owner Guest

    Default New telescope design

    rander3127 wrote:

    And diffraction spikes too

    -tom

  8. #8
    Colin J Denman's Avatar
    Colin J Denman Guest

    Default New telescope design

    vic20owner <vic20owner@yahoo.com> wrote in
    news:f%J7d.62565$uN5.3873@tornado.tampabay.rr.com:


    Someone will "Schmidt-ize" it. But I'd be wondering how they get the light
    out to an eyepiece if the _only_ secondary mirror is reflecting light down
    to the convex bit of the primary.

    --
    Colin J Denman
    N 51º 54' 38" W 00º 29' 45" Elev: 125m
    email: mailto:spam@cjdenman.freeserve.co.uk -- use my first name
    home: http://www.cjdenman.freeserve.co.uk

  9. #9
    Chris L Peterson's Avatar
    Chris L Peterson Guest

    Default New telescope design

    On 03 Oct 2004 04:26:20 GMT, Colin J Denman <spam@cjdenman.freeserve.co.uk>
    wrote:


    The light hits the "secondary" twice (it is really a secondary and a quaternary
    mirror), and is finally directed through a central hole in the primary (or
    tertiary, if you prefer) and out the back. The imager or energy sensor would be
    located there. I doubt it would ever be used with an eyepiece. I also doubt it
    would ever be built with the forward mirror on a window. Diffraction spikes are
    only an issue of aesthetics, and this design is probably never going to be used
    visually or for aesthetic imaging.

    _________________________________________________

    Chris L Peterson
    Cloudbait Observatory
    http://www.cloudbait.com

  10. #10
    Colin J Denman's Avatar
    Colin J Denman Guest

    Default New telescope design

    Chris L Peterson <clp@alumni.caltech.edu> wrote in
    news:i8vvl0pqubmo4emfke8e9inav9rmiv3711@4ax.com:


    I've not seen the instrument in question, so I take your other points, but
    can't quite let this one pass. All diffraction artefacts are a degradation
    of the image quality. As such no one designs a scope with aesthetic
    diffraction patterns (do they?), they're usually a mechanical trade off or
    unavoidable optical limitation. Though I'm aware (but find it hard to
    believe) that some people take images through SCTs and then add spikes in
    software!

    Being pedantic,
    --
    Colin J Denman
    N 51º 54' 38" W 00º 29' 45" Elev: 125m
    email: mailto:spam@cjdenman.freeserve.co.uk -- use my first name
    home: http://www.cjdenman.freeserve.co.uk

 

 
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