I’ve been watching my “From the Earth to the Moon” HBO DVDs, and I’ve noticed that the astronauts on the Moon occasionally lift their visors, so we can see their faces. But I recall, when the Moonwalks were actually happening, that the astronauts did not lift their visors. At least not that we watching TV on Earth could see.
My question: Did the Apollo astronauts on the Moon lift their visors, so as to see the Moonscape better? Or Earth? Or whatever?
They might have kept the visor down during the day most of the time for the simple reason that the sunlight would be more intense than what they’d get on Earth (at least at the same latitude) due to lack of atmospheric filtering. Presumably they’d lift it up to get a better look at things or for photo ops from time to time
All of those pictures clearly show light reflecting off of a transparent visor. Perhaps an outer shell - polarized or darkened against bright light and glare - could be raised while leaving the transparent, airtight inner part in place.
The gold-covered sun visor is the one that conceals the face in many shots; I expect that Schmitt preferred to raise this wherever possible - as a geologist he would want to see the true colours of the rocks.
They can’t be polarized because it prevents them from viewing LCD instruments. The coating on the visor is essentially the same sort of glare reduction mirror coating you find on Oakley (or almost any non-fashion) sunglasses.
Which LCD-based displays are you aware of in any of the Apollo missions? Bear in mind, the first viable LCD technology came out in 1971. That eliminates all Apollo missions before 14, and that flew in January of that year. Given engineering lead-up times, I’d be amazed if they integrated new display technology within the same year as its introduction, so write off everything except Apollo 16 and 17 (1972).
Even if they had LCD displays, it’s trivial to design LCD displays that can be seen through polarizing filters. All you have to do is orient the polarizer in the LCD correctly, so that the light from it is vertically polarized. If the device is designed to be used in both orientations (landscape & portrait), you orient the polarizer at a 45 degree angle. (And in fact, I think most LCD displays have the polarizer at 45 degree angle, I think for this very reason.)
It’s trivial if the people looking at the displays are going to be in a fixed position and are unable to move their heads. In practice, that’s not how things work. That’s why pilots don’t wear polarized sunglasses.
Anti-glare filters are polarizers, but not an integral part of the LCD display.
It really is trivial to design LCD displays that can be seen through polarized sunglasses, if that is your goal. It will go dark if you literally tilt your head 90 degrees, but the chances of that happening in real life is vanishingly small. Or you could put a quarter-wave plate in front of the screen, thus creating a circularly polarized light which can be seen at any any angle.