What a funny coincidence! I just visited the Reichstag today in Berlin and it turns out that inside the glass dome they have this shade that rotates parallel to the sun to protect the mirror column from bright light. The shade is actually a large wire grill similar to the guys goggles to let in partial light.
In the top right corner of the pic I took you can see part of the big grill (pic is kinda big, might have to stretch out your browser)
Hehe, Maybe I'll try some of those colorful sunglasses with slits in them the next time I come by the flying field
Probably be limiting my sight distance big time.