Explain the newer 3D technology

So I saw Avatar in 3D, and we were examining the glasses afterward. I thought that the newer 3D films used polarized light, but I have two problems understanding this.

  1. How do you put polarized light off a screen? I was told that reflected light was polarized by the reflection. Is polarized light still in the same orientation because it was polarized first?

  2. We showed that if you put a right lens over a left lens, you get black. This didn’t change by rotating them. Other polarized films I’ve seen did.

I know on this board there’s someone who knows, and even possibly someone who did a technical paper on the method. Thanks.

I know the glasses are polarized in spirals one clockwise the other side anti-clockwise. But that’s the limit of my knowledge.

For release in regular theaters, Avatar used the RealD Cinema 3D system, utilizing a single digital projector fitted with a digital circular polarizer. The glasses are passive circular polarized lenses. The system is described in more detail here (PDF). The key appears to be circular polarization, as opposed to linear polarization. The 3D system used in IMax theaters used a different system.