Polarization interference sunglasses

Are there any opticians here?

My wife has very sensitive eyes, and has a hard time getting sunglasses that are dark enough. Opticians always claim that "that's as dark as we can get them", the process clearly being dyeing.

Wouldn't it be possible to grind two polarized lenses and glue them together at a particular angle? It seems to me that you could pretty easily select 50% to nearly 100% with that method. I recognize that it would obviously be harder to accomplish than with dyeing, but it would solve her problem.

Anyone have any feedback?

Sounds reasonable.

Cheaper might be some simple windscreen tint (self-stick) plastic, cut and stuck over existing sunglass lenses.

??

Well, I was thinking of a more professional solution, but, yeah, that ought to work too.

Metalization (gold via vapor deposition) can give you any grade you desire, right down to stare at the sun darkening.

Souds like she needs a set of these from 1940!

lol

Or- maybe find one of those tinted face shields that the asian women wear and put on a pair of sunglasses under that.
I'll be danged if I can conjure a GIS image for that face shield, though. Weak fu today.

edit:
Ah- here's some info and pics.

Damn, I pulled the image up so fast (not because it's my desktop image), that I didn't notice the link at the end of the previous post...

You'd get a moire pattern.

I've personally looked through two polarized planes and there is no moire.

In fact, so have you, because that's how LCDs work.

You would only get that in cars, and only because of the way the windshields are polarized. I think It's a cool looking effect, actually. I saw a while back some electronic blinds that used LCD tech to turn darker. One plate was polarized at 90 and the lcd was polarized at 180. By applying a weak electrical current to the LCD, the entire window just got darker. It even included a remote control.

Bull. I've got a sextant with filters on it that allows you to look directly at the sun.

Clearly, as she's had glasses darker than that before. But there's got to be some technique that they use exclusively these days. It's not a problem unique to one optician. Maybe it has to do with plastic versus glass.

Is she looking for prescription sunglasses, or just regular sunglasses? If the latter, perhaps she could try mountaineering sunglasses, which are (sometimes) significantly darker than the regular variety.

Prescription. But it's still a good point that they might make prescription mountaineering sunglasses.

I suspect the problem is that today a lot of eyeglasses are made using prefabricated lenses. Tints are standardized and stocked in a warehouse. Blame the inexpensive 1 hr Eyeglass shops for that revolution.

From past experience, I do know that opticians are wary about supplying extra dark tints. You may have to wave any satisfaction guarantee.

Either Fishy needs to hang out on this BBS more, or you guys need to be on LiveJournal and friend him:

http://gfish.livejournal.com/278884.html

If you ask somebody at a smaller independent opticians then they might be able to help. I have to get my lenses specially ordered because I'm about -2 in both eyes but have a high astigmatism. If I just got regular lenses then they'd be pretty thick.