Half a croissant, on a plate, with a sign in front of it saying '50c'
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It's dark and we're wearing sunglasses

One-way shades for wearing at night
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When your shades are an intrinsic part of your fancy-dress costume (Neo, Blues Brothers etc), it can be irritating to have to remove them to facilitate vision in dark parties/clubs – relegating your persona to a bloke in a suit.

These shades use the same material as one-way shaded glass, allowing light in one way but not the other, so you can see everything when it's dark but you still have your shades on.

Can also be worn by morons on the tube.

theleopard, Dec 04 2009

[link]






       ...or, the glasses could look like very dark glasses but be entirely opaque. The wearer would see the world in front of them in tiny LCD screens on the back of each lens projected into the eye through corrective lenses. This would have the advantage that IR/night-vision modes could be used, and the screens could also support the display of text messages, stock information, song lyrics, chat-up line hints, etc.
hippo, Dec 04 2009
  

       These are called mirrored sunglasses.
ldischler, Dec 04 2009
  

       Mirrored sunglasses still blot out the sun, or in this case the ambient light from the bar, so you'd still have to take them off to see anyone or anything around you.
theleopard, Dec 04 2009
  

       Maybe so, but what you described is still mirrored sunglasses.
ldischler, Dec 04 2009
  

       Then you're right, it is a good name for them.
theleopard, Dec 04 2009
  

       One way glass is still tinted glass, it will still reduce the light reaching the eyes. There is no such thing as a glass that will appear dark from one direction and pass all the light to the other.
MechE, Dec 04 2009
  

       Do these only work when you're 206 miles from Chicago?
Dub, Dec 04 2009
  

       Moron.
theleopard, Dec 04 2009
  

       [bigsleep] has it. +
csea, Dec 05 2009
  

       Thanks for the link, bigsleep. I didn't know a metal film could photo-bleach (or the reverse of that, actually), though I suspect this effect is confined to surface in contact with silica. This doesn't apply to theleopard's idea, of course, which doesn't say anything about changing reflectivity--it's just the wearing of ordinary mirrored sunglasses indoors.
ldischler, Dec 05 2009
  

       Transmittance, in the dark, of 45%, you're still losing half your light at any time.
MechE, Dec 05 2009
  

       Yes, theleopard has the common misconception that a one way mirror is exactly what it says (thus violating the second law of thermodynamics and earning an MFD for bad science.) Instead, one way mirrors work by camouflage--the image from the dim side of a partially reflecting mirror is lost in the reflection from the bright side.
ldischler, Dec 05 2009
  

       [m-f-d retracted] bad science
notexactly, Dec 05 2019
  

       [m-f-d] disputed, since there is actually a way of doing this using a concentric microetched fresnel-mirror-fresnel assembly which delivers better than 86% of incident light to the observer, but with near-zero reflectance to the source (though there is reflectance, it's scattered through 140°).   

       Very useful for concealing large-aperture weapons optics; no glint, in the vis & IR bands they appear black.
8th of 7, Dec 05 2019
  

       //concentric microetched fresnel-mirror-fresnel assembly//
Do you have a handy link for more detail on this? (To save me trawling through Google...)
neutrinos_shadow, Dec 05 2019
  

       No, and you won't find one either, so don't bother.
8th of 7, Dec 05 2019
  

       I've got a couple somewhere in the shed, but it's dark in there and I'm damned if I can find them.
MaxwellBuchanan, Dec 05 2019
  

       The skin doesn't absorb(/reflect) all frequencies, equally. So, selecting the filter component(s) to block peaks of skin reflectance will reduce the mirror effect. Downside of course is that for the wearer, other people's faces will be darkened, as well.
FlyingToaster, Dec 05 2019
  

       //a way of doing this ... which delivers better than 86% of incident light to the observer, but with near-zero reflectance to the source//   

       Hold on a moment. All you're saying is that there are things that let light through and don't reflect much of it. This is hardly rocket surgery.
MaxwellBuchanan, Dec 05 2019
  

       No,we're telling you that they're almost entirely opaque (and absorbant i.e. black) when vewed from one side, yet close to transparent from the other.   

       Not a "one-way mirror", more of a one-way wall...
8th of 7, Dec 06 2019
  

       Wow. OK. Turns out [theleopard] got really lucky here, and this is no longer bad science. [Chairborne Hero], you're living up to your name.
notexactly, Dec 08 2019
  

       Transitions lenses, anyone?
RayfordSteele, Dec 08 2019
  

       // got really lucky here, and this is no longer bad science. //   

       No luck involved; sometimes it takes reality a while to catch up, is all.   

       <Looks round hopefully for flying car as promised in 1960's/>
8th of 7, Dec 08 2019
  
      
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