# Are those 3d glasses good for anything else? **URL:** \ **Category:** Factual Questions\ **Created:** [August 31, 2010, 3:06pm UTC](https://boards.straightdope.com/t/are-those-3d-glasses-good-for-anything-else/552139 "2010-08-31T15:06:12Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![notsoheavyd3](https://avatars.discourse-cdn.com/v4/letter/n/85e7bf/32.png) [@notsoheavyd3](https://boards.straightdope.com/u/notsoheavyd3)\ **Post date:** [August 31, 2010, 3:06pm UTC](https://boards.straightdope.com/t/are-those-3d-glasses-good-for-anything-else/552139/1 "2010-08-31T15:06:12Z")
So a month or so back I saw Despicable Me in 3D with those 3d glasses. When I left the cinema I was tempted to keep them as a souvenir but I recycled them. I’m kind of curious, if I had kept them is there anything neat that you could do with them? (I mean they’re not the kind of polarized lenses that you can use to cut down glare, right?) ---
**Author:** ![Darth\_Sensitive](https://avatars.discourse-cdn.com/v4/letter/d/58956e/32.png) [@Darth\_Sensitive](https://boards.straightdope.com/u/Darth_Sensitive)\ **Post date:** [August 31, 2010, 3:19pm UTC](https://boards.straightdope.com/t/are-those-3d-glasses-good-for-anything-else/552139/2 "2010-08-31T15:19:46Z")
I have a pair in my car for use as backup driving sunglasses. They may not cut down on glare, but they at least damp down the brightness. I wear glasses generally, so they fit over my normal pair. So I can use them if not wearing contacts - might look dumb, but hey, it gets real bright in Oklahoma. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [August 31, 2010, 3:56pm UTC](https://boards.straightdope.com/t/are-those-3d-glasses-good-for-anything-else/552139/3 "2010-08-31T15:56:12Z")
you can use them for nifty science demonstrations and for learning about polarization. I believe that each lens has a linear polarizer and a circular polarizer (or a half wave plate). If you cut the lenses apart and place them so that the outer parts face each other, then rotate them, you can get them to completely block each other and get little light through. If you try putting them together in any other combination, this won’t happen. If you look at things through an individual polarizer with what was originally the part nearest your eye still there, you can rotate the polarizer and watch as reflection from surfaces near Brewster’s angle disappear. you can also look at the blue sky and watch 9as you rotate the polarizer) the blue sky darken away from the sun, showing that rayleigh scattering is maximally polarized at 90 degrees. You can also do nifty experiments with Corn Syrup between crossed polarizers, but you have to pay attention to the way the polarizers are ordered – as I say, they’re not simple linear polarizers. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 31, 2010, 4:56pm UTC](https://boards.straightdope.com/t/are-those-3d-glasses-good-for-anything-else/552139/4 "2010-08-31T16:56:15Z")
> [@](#): > > I believe that each lens has a linear polarizer and a circular polarizer (or a half wave plate). The front layer has a filter that converts circularly-polarized light to linear (I think that’s a quarter-wave plate?). The back layer is a conventional linear polarizer. So if you put two lenses together front-to-front, then they’ll either let as much light through as a single lens, or let essentially none at all through, depending on which lenses you use (but not depending on angle). If you put two together back-to-back, then it will depend on the angle. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [August 31, 2010, 5:43pm UTC](https://boards.straightdope.com/t/are-those-3d-glasses-good-for-anything-else/552139/5 "2010-08-31T17:43:30Z")
> [@](#): > > The front layer has a filter that converts circularly-polarized light to linear (I think that’s a quarter-wave plate?) I don’t think that’s right. When I look at the arms of the seats through the glasses, I see reduced glare. That happens because of Malus’ Law and the reduction of linearly polarized light – there’s no analogous effect with circularly polarized light. So the top layer (the one closest to the screen and away from my eyes) has to be a linear polarizer. And it;'s not because I’m seeing circularly polarized light reflected from the screen – I see the effect before the movie starts, with light reflected from the overhead lights and Exit signs. ---
**Author:** ![Iggins](https://avatars.discourse-cdn.com/v4/letter/i/b9e5f3/32.png) [@Iggins](https://boards.straightdope.com/u/Iggins)\ **Post date:** [August 31, 2010, 5:52pm UTC](https://boards.straightdope.com/t/are-those-3d-glasses-good-for-anything-else/552139/6 "2010-08-31T17:52:58Z")
Since this is answered, I’ll also add that you can wear them ironically, in a hipster sort of way. I’m seeing that more and more… ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [August 31, 2010, 6:00pm UTC](https://boards.straightdope.com/t/are-those-3d-glasses-good-for-anything-else/552139/7 "2010-08-31T18:00:22Z")
> [@Iggins](#): > > Since this is answered, I’ll also add that you can wear them ironically, in a hipster sort of way. I’m seeing that more and more… Nobody wears polarized lenses ironically. To be really hip, you have to look like [Biff’s minion](http://www.nineinchsandwich.com/wp-content/uploads/2010/03/biff-back-to-the-future.jpg). ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 31, 2010, 6:37pm UTC](https://boards.straightdope.com/t/are-those-3d-glasses-good-for-anything-else/552139/8 "2010-08-31T18:37:39Z")
> [@](#): > > I don’t think that’s right. When I look at the arms of the seats through the glasses, I see reduced glare. That happens because of Malus’ Law and the reduction of linearly polarized light – there’s no analogous effect with circularly polarized light. So the top layer (the one closest to the screen and away from my eyes) has to be a linear polarizer. I have never seen this effect. And when I look at my wristwatch (which has a linear polarizer on it) through a pair of movie glasses, I see almost no change when I rotate the watch or glasses. However, when I look through a pair of movie glasses backwards (with the earpieces jutting out in front), I do see a strong rotation dependence with my watch. I’m guessing that the reduction in glare you were seeing was just from a general reduction in intensity, and not polarization-specific. That, or you were experimenting with them in the theater, and forgot that you were looking through them backwards when you saw that. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [August 31, 2010, 6:40pm UTC](https://boards.straightdope.com/t/are-those-3d-glasses-good-for-anything-else/552139/9 "2010-08-31T18:40:06Z")
> [@](#): > > I’m guessing that the reduction in glare you were seeing was just from a general reduction in intensity, and not polarization-specific. Definitely not – I saw the reduction with one eye, and not with the other. The only reason it stood out was because it was clearly eye-dependent. And I was wearing my glasses right-side out. I’ll haveto experiment with the set I brought home. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 31, 2010, 8:47pm UTC](https://boards.straightdope.com/t/are-those-3d-glasses-good-for-anything-else/552139/10 "2010-08-31T20:47:07Z")
Were they IMAX 3D, or RealD? I think I’ve heard that IMAX still uses linearly-polarized projection; that might account for it. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [August 31, 2010, 8:49pm UTC](https://boards.straightdope.com/t/are-those-3d-glasses-good-for-anything-else/552139/11 "2010-08-31T20:49:13Z")
> [@](#): > > I think I’ve heard that IMAX still uses linearly-polarized projection; that might account for it. Yeah, they were IMAX from the time I saw Avatar. I admit that I was surprised, because I thought that the outside was supposed to be circularly-polarized, as you say. But I saw that clear polarized loss of glare from the seat arms and it took me by surprise. ---
**Author:** ![thirdname](https://avatars.discourse-cdn.com/v4/letter/t/d07c76/32.png) [@thirdname](https://boards.straightdope.com/u/thirdname)\ **Post date:** [August 31, 2010, 9:08pm UTC](https://boards.straightdope.com/t/are-those-3d-glasses-good-for-anything-else/552139/12 "2010-08-31T21:08:46Z")
There is stereo porn available on the Internet that can be viewed with the red-blue type glasses. ---
**Author:** ![King\_Solomon\_Hill](https://avatars.discourse-cdn.com/v4/letter/k/59ef9b/32.png) [@King\_Solomon\_Hill](https://boards.straightdope.com/u/King_Solomon_Hill)\ **Post date:** [August 31, 2010, 9:10pm UTC](https://boards.straightdope.com/t/are-those-3d-glasses-good-for-anything-else/552139/13 "2010-08-31T21:10:24Z")
For a very simple and non destructive demonstration of the polarising filter in these glasses try wearing a pair when looking in a mirror. Close one eye - you get a pretty startling effect. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 31, 2010, 9:18pm UTC](https://boards.straightdope.com/t/are-those-3d-glasses-good-for-anything-else/552139/14 "2010-08-31T21:18:12Z")
A bit of checking confirms that [IMAX 3D uses linear polarization](http://en.wikipedia.org/wiki/IMAX#IMAX_3D), as opposed to the circular polarization in [RealD](http://en.wikipedia.org/wiki/RealD_3D). I’m not sure why IMAX would still use linear, unless maybe it’s a patent problem. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [September 1, 2010, 12:12pm UTC](https://boards.straightdope.com/t/are-those-3d-glasses-good-for-anything-else/552139/15 "2010-09-01T12:12:11Z")
I pulled out the Real3D glasses I brought home , and they do indeed provide crossed polarization when you place them inside-to-inside. Another pair I have (presumably from seeing Avatar) do work the other way around.