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Building infinity corrected microscope from non-infinity corrected objective

  1. May 23, 2012 #1
    Hi there
    As is known using non-infinity corrected objectives in infinity corrected microscopes is not a good idea because of many reasons (image quality will be degraded, back focal plane will be in wrong place, parfocal distance is not preserved, etc.).
    What about building infinity corrected microscope from the scratch using non-infinity corrected objective: is it possible? Are there any design differences between the two kinds of objectives that does not allow this or at least have to be handled properly?
    Anyway, references to microscope design books are highly appreciated.
  2. jcsd
  3. May 23, 2012 #2

    Andy Resnick

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    Doing that would be incredibly painful- why not start with an infinity corrected objective lens? There are two major benefits to infinity-corrected microscopes:

    1) Putting optical components (polarizers, beamsplitters, waveplates, etc) in 'infinity space' does not change the optical path length, so your object remains in focus as these components are inserted or removed

    2) aberration balancing can be performed with the tube lens- the objective lens doesn't have to be fully corrected, resulting in a simpler (less expensive) lens. This unfortunately means that, for example, non-Leica objectives can't be used in a Leica microscope (as opposed to the non-infinity corrected objectives which can be used in any microscope)
  4. May 23, 2012 #3
    Hi Andy
    Thanks for your reply. Sorry if my question was not clear enough but it seems to me that you misunderstand it a little so I'll try to rephrase it.
    I'm not asking about replacing an objective in already made microscope but rather about building microscope from spare components by myself so I can place elements at any distances from each other. Unfortunately the lenses I'd like to use are not infinity corrected (Murphy's law).
    I understand why infinity optics is better. To be simple it looks like this:
    1) object (placed in focal plane of the objective lens)
    2) infinity-corrected objective lens
    3) "infinity space" = parallel beams = right place for additional components
    4) tube lens
    5) image (located in focal plane of the tube lens)
    Imagine that we replaced the "infinity-corrected objective lens" with "non-infinity-corrected one" but properly placed so its focal plane also coincides with the object and it will also produce parallel beams after it. It seems that this setup should remain "infinity corrected". But how it will perform in this case? How much image quality will degrade and what about aberrations?
    So my question is:
    If objective was initially designed for non-infinity-corrected setup then does it perform equally well when placed properly in infinity-corrected optical setup?
  5. May 24, 2012 #4

    Andy Resnick

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    Probably not. I expect there will be a lot of distortion and field curvature.
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