Interesting article about NSA facility and capabilities

Ben Liddicott ben at
Tue Mar 27 21:10:38 BST 2012

Sadly that is yet to be invented. One-way mirrors work because the 
"observed" mirror side is light and the "observer" side is dark, so the 
reflected light is much greater than the transmitted light in both 
directions - but both sides can only see the "observed" side as it is much 
greater in magnitude.

(Only one side has to be reflective - light can be absorbed in one direction 
and reflected in the other, but the transmission will be pretty much the 
same in both directions, modulo a small amount of cleverness with internal 

Actually, having written that, I suppose a good question would be is a 
partially mirrored glass permitted if the transmissivity is 70% or greater? 
Certainly it will be much darker in the car than outside so it would still 

Just had a look at the construction and use regulations and this is not 
mentioned, only the transmission of light.

So , yes.

-----Original Message----- 
From: Roland Perry
Sent: Tuesday, March 27, 2012 4:56 PM

Is one-way glass allowed (<30% attenuation one way, 100% the other)?

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