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New Metallic Glass Creates Potential For Smart Windows
frank249 writes: A B.C. engineering lab has created metal-coated glass that transmits up to 10 per cent more light than conventional glass and opens the door to windows that function as electronics. The most immediate use of the technology is to create windows that can be programmed to absorb or reflect heat, depending on the needs of a building's occupants. Adding electronic control to windows will allow you to change the amount of light and heat passing through to more effectively use the energy provided by the sun naturally, Lead investigator Kenneth Chau credit films like Iron Man or Star Trek with providing them inspiration. "There is a dream that we can make glass smarter," he said. "These films give us concepts to strive for; the hard work is uncovering the science to make it happen." All those hours spent watching Star Trek are now starting to look like a "pretty good investment," he said. The results were published this week in the journal Scientific Reports.
That is one of those Wikipedia articles which is a bit vague about what it means. It's doesn't make sense to intend to say that glass transmits 90% of incident light regardless of the thickness. The Wikipedia entry references a single optical "element", so I'd take "the transmissivity of one element (two surfaces) is about 90%," to mean that 10% is the lower limit of light loss for a single lens of arbitrary thinness.
Now if a very thin silica glass lens transmits 90% of the light falling on it, then clearly it'd be very difficult to conceive of a material that transmits 10% more light than that. However you can achieve whatever level of attenuation you wish by making your piece of glass sufficiently (possibly absurdly) thick. The three inch thick glass panes used in giant ocean tanks are noticeably more opaque than air. Clearly it's physically possible for a material to transmit 10% more light than the same thickness of glass -- for a sufficient thickness. Particularly if the index of refraction of that material is closer to air.
Of course that's where we get to the point that the summary is badly written too. Silica glass *is* very transparent; insufficient transparency isn't a problem in window applications, if there's a problem it's that the material is too transparent. That's why we have dark tinting and anti-IR coating. So it's not clear why we would care that the material can transmit 10% more light. Clearly the story got garbled somewhere along the way.
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It's not "metallic glass," which describes (or should) a metal that's cooled fast enough not to be able to form a crystalline structure -- see also "metal ceramics." It's "metallized glass," which is the correct description of putting a layer of something on top of glass.
I also find it hard to believe that the quoted researcher said that glass is a crystal, since it isn't.
https://app.box.com/WitthoftResume Code: https://github.com/cellocgw
“Glass is a crystalline structure that is fairly transparent, but not completely, you can still see it."
Um... noooo, glass is a glass, denoted by its lack of a crystalline structure unless you're talking about devitrified glass, which is typically too weak to use in any practical application.