- One common method for displaying 3D films uses polarized light. Two images are projected simultaneously, each polarized differently (e.g., linearly polarized at 90 degrees to each other, or circularly polarized in opposite directions). - The 3D glasses contain polarizing filters (polaroids) that match the polarization of the projected images. The filter over the left eye allows only the image intended for the left eye to pass through, and the filter over the right eye allows only the image intended for the right eye. - The brain then combines these two slightly different images to create the perception of depth.