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Passive night vision scopes?

  1. Aug 7, 2009 #1
    Has anyone ever created a monocular (or binocular) for the main purpose of simply gathering more light without much, if any, telephoto effect? A cursory google of it shows me nothing. I guess I'm surprised there aren't old WW2 surplus "passive night vision systems" out there that are simply lens systems held to the eye but that have a huge objective lens with hardly any telephoto capability, in order to work with moonlight, twilight, man-made ambient light, or even starlight. (Note: I did find a so-called "passive" system that still uses electronic amplification of visible light--I'm not sure why it was called passive, then!)
     
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  3. Aug 7, 2009 #2

    MATLABdude

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    Most of them do! Just turn off / cover up the illuminator (with something that's IR opaque, like aluminum foil).

    If you mean completely passive, light gathering devices, they've had them since at least World War II: night glasses (or night glass binoculars). Large aperture glasses (can't make them too big, otherwise they aren't portable or you won't be able to resolve anything), sometimes issued with atropine eye drops to dilate the pupils and allow more light to enter the eyes (beyond what normal night vision gives you):
    http://en.wikipedia.org/wiki/Night_vision#Night_glasses

    They're still sold:
    http://www.beststuff.com/fromthewire/deutsche-optik-introduces-new-night-glass-binoculars.html
     
    Last edited by a moderator: Apr 24, 2017
  4. Aug 7, 2009 #3
    Awesome! Thanks for the help :)
     
    Last edited by a moderator: Apr 24, 2017
  5. Aug 7, 2009 #4

    Andy Resnick

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    Not sure what you mean by 'passive' amplification, other than simply having a large entrance pupil: most binolculars fufill that purpose.

    'night vision' goggles, and there are several technologies, are usually powered- there is some amplification provided electronically (for example, microchannel plates). I think these are called 'passive' since they do not illuminate the scene. 'Active' systems generally illuminate the scene somehow, and there may be an amplified imager to detect.

    Does that help?
     
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