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Change-colour eye-glasses

Are they available?
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(+2)
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We have auto-darkening-lightening glasses in differing shades. Is there any technical reason why press-a-button colour-change specs could not be developed? Should be good sellers. I did a short web search of markets with no result.
rayfo, May 02 2001

neon and fluorescent lights http://www.howstuff...com/question293.htm
for potatostew [mihali, May 02 2001, last modified Oct 04 2004]

18.9 what chemicals change colour with heat, light, or pressure? http://www.faqs.org...part5/preamble.html
for potatostew 2 [mihali, May 02 2001, last modified Oct 04 2004]

[link]






       Would they change hue, or just brightness? The latter seems more plausible.
egnor, May 02 2001
  

       [egnor: your post came up while my neuron was struggling with rayfo's idea. I assumed he meant different colors]   

       I think you'd have to use pigments with two seperate properties: photosensitivity so that the pigment would darken in the presence of light, and a property that either activated or deactivated the photosensitive property. In theory I can imagine a chemical which becomes photosensitive when a small electrical current is passed through it, or one which is activated by an increase in pressure (as when the lens is squeezed top-to-bottom, for instance). But I don't know that pigments with these properties actually exist. And you'd have to arrange your different-colored pigments so that each was activated by something which did not activate the others.   

       Which makes these eyeglasses quite appropriately halfbaked, to my mind.
Dog Ed, May 02 2001
  

       If your lenses were made of three layers of liquid crystal, each of which included a coloured filter, you could 'select' each layer electrically to activate the required colour. The liquid crystal could also be divided into pixels, each addressable individually (pretty much how LCD televisions work), so you even have pictures on your glasses (pretty much how VR displays work).
angel, May 02 2001
  

       They have now developed a security type glass which has a (I think LCD) thingy built in. Normally the glass is Blacked out, but as you apply a current the glass slowly becomes clear. Proposed as an alternative to blinds for privacy and to shut out bright light.   

       This was on "Tommorows World" about 6 months ago. It's probably available on the market somewhere by now.
CasaLoco, May 02 2001
  

       Are there any gasses or liquids that can be made to change color by applying electricity or by some other reversible means?
PotatoStew, May 02 2001
  

       you mean like neon and fluorescent lights? see link.
mihali, May 02 2001
  

       Sort of, but not exactly. For neon to work, you'd have to exchange the gases somehow. Plus you would be blinded by the results. With a fluorescent solution, the phosphor coating would keep you from seeing through the glasses. And again, you'd be blinded. Not very functional for glasses.   

       I was kind of hoping there was a gas that would simply change color, rather than emit light.
PotatoStew, May 02 2001
  

       ah - okay, i see what you mean. you should try the next link then. scroll down to the section entitled "18.9 what chemicals change colour with heat, light, or pressure?".
mihali, May 02 2001
  
      
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