Why settle for a one-way mirror when you can have both properties in 1 pane of glass/mirror? MIT Scientists have invented an invisible mirror that can show reflections as well as be seen through like a window. Alternating 84 layers of glass and tantalim oxide make this one of the coolest things we’ve seen.
New scientist writes:
As light passes from one of these layers to the next, some gets partially reflected – except for light that approaches from a certain angle. Any light that hits the surface of a layer at this so-called Brewster angle, and with a particular polarisation, will pass straight through as if the surface wasn’t there. The Brewster angle is different for each pair of materials as it depends on their refractive indices.