a guy called Michiel Kassies holds a european patent on a structure like that, this was obtained somewhere in '86 so in europe probably at or near expiry. I don't know how to find European patents online otherwise I'd look it up, filing date was probably late '85 or early '86.

The thing was wedge shaped for better aerodynamics but looked from the inside of a car like a normal side mirror. No clue anymore how the thing worked exactly except that it was lots and lots of thin sheets with all kinds of interesting properties.