# IMAX Glasses and Polarized Light

Posted on: June 11, 2008

I was just at the IMAX this week on a school trip and I asked to keep two pairs of the glasses for my classroom. I asked. I’m not one to steal, even something like these inexpensive 3D glasses.

The way IMAX creates 3D is by polarizing the image on the screen so that light for the left eye is 90° out of phase with the light for the right eye. You can easily demonstrate this by first placing the glasses over top of one another, left lens over left lens. You can clearly see through both the doubled left and right lenses as in the picture on the right. The picture below shows the left lens of the front glasses over the right lens of the rear pair. The middle lens pair is black. You can click on these images to get a full size view.

Now turn one pair of glasses 90° to the other and cover the left lens with the rotated left lens. The glasses are now dark. Move the rotated left lens over the right lens and the image is clear again. Now repeat this with the right lens from the beginning. Clearly the left and right lens are out of phase.

I’m not sure how they create this image on the screen. My best guess is that they have a dual projection system that goes through similarly polarized filters. I believe that the separation distances are going to generate the depth. If someone knows for certain, please post the details.

### 3 Responses to "IMAX Glasses and Polarized Light"

3D glasses like these (a feather works too) and a laser pointer can also demonstrate diffraction, if you hold both carefully.

Hey there I have got the 3d home imax system and it is a lot simpler than it seems. The software converts the video into two images, one for the left eye and one for the right and images alternate at high speed like a strobe. What the glasses do is act like a shutter which close one eye while the screen flashes the image to the other, it does this back and forth with each eye viewing the image meant for it. This is done at high speed so you percieve only the one image, in 3d.

I can’t see 3D because I have monocular vision – my left eye cornea never developed enough to see or is too badly damaged. For whatever reason, I only see with my right eye. It adds a bit to the discussion of 3D in my classes. And my students think I am a freak!

### What’s New in 2013/2014?

Every year brings a change, this one is no exception.

I will be picking up the sophomore honors Algebra II class to keep them separate from the juniors. This should help accelerate them and put them on a stronger track towards Calculus. Looks like there will be only one section each of Physics and Calculus, but still two of Robotics & Engineering.

Hot topics this year are going to be the Common-Core Standards, Standards-Based Grading (SBG), improving AP Calculus scores, and somehow adding Python, maybe as a club.

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