Undetectable Surveillance Window Patent Awarded

OK, so there's no cat to be found anywhere in the real patent award for Thales' surveillance window. But we're still watching you, citizen, thanks to a spy panel cleverly made to resemble a dull and opaque window. It can even be made to look like, say, an acrylic "EXIT" sign.

Currently, the filing's authors write, the two-way mirrors and neutral density filters are the state of the art when it comes to sneaky observation. Unfortunately, everyone knows what they look like and "members of the general public are suspicious of any mirrored surface" as a result. Neutral density filters absorb instead of reflect light, creating a more convincing illusion of normality — but one that reveals to perceptive subjects the silhouette of observers behind it.