Do Passive Night Vision Scopes Exist Without Electronic Amplification?

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Discussion Overview

The discussion revolves around the existence and design of passive night vision scopes, specifically monoculars or binoculars that gather light without electronic amplification. Participants explore historical and contemporary examples, as well as the definitions of passive versus active night vision systems.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions why there are no simple passive night vision systems with large objective lenses that do not provide telephoto effects, expressing surprise at the lack of such devices in surplus markets.
  • Another participant asserts that passive light-gathering devices have existed since World War II, mentioning "night glasses" or "night glass binoculars" that utilize large apertures and may include pupil-dilating eye drops to enhance light entry.
  • A participant suggests that many night vision devices can be made passive by covering or turning off their illuminators, although they acknowledge that most night vision goggles involve some electronic amplification.
  • There is a clarification regarding the term 'passive' in night vision, with one participant explaining that it typically refers to systems that do not illuminate the scene, contrasting them with 'active' systems that do.

Areas of Agreement / Disagreement

Participants express differing views on the definitions and capabilities of passive night vision systems. While some agree on the existence of historical passive devices, others challenge the clarity of the term 'passive' and its application to modern technology.

Contextual Notes

There are unresolved questions regarding the definitions of passive and active systems, as well as the specific characteristics that would classify a device as passive. The discussion also highlights the potential limitations of existing designs in terms of portability and effectiveness.

fleem
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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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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
 
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MATLABdude said:
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

Awesome! Thanks for the help :)
 
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fleem said:
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!)

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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