Glasses-free 3D is an appealing proposition. Hell, that’s what Nintendo banked an entire handheld gaming console on with the 3DS when they originally released it. There are people who enjoy 3D, but even those don’t particularly enjoy wearing clunky glasses to get the job done. This is especially true of the home 3D market, where brands have been working and crafting their own glasses-free displays. Yet, movie theaters, with their size and seemed destined to keep those glasses on your head forever.
An optics research group based out of South Korea have discovered a way to bring glasses-less displays into commercial theaters. In a paper that was published yesterday, they described their new technique which they claim would also be less expensive than current 3D projection set ups. That could mean, 3D ticket prices could become cheaper as well (which can also be a deterrent to many people). The paper is filled with lots of info and facts, and I’m sure I’d do a terrible job of paraphrasing. Instead, I’m just going to let you read the pertinent info:
“There has been much progress in the last 10 years in improving the viewers’ experience with 3-D,” notes the team’s lead researcher Byoungho Lee, professor at the School of Electrical Engineering, Seoul National University in South Korea. “We want to take it to the next step with a method that, if validated by further research, might constitute a simple, compact, and cost-effective approach to producing widely available 3-D cinema, while also eliminating the need for wearing polarizing glasses.”
(Actual experimental results demonstrate the promise of a glasses-free 3-D theater experience. Two cars, one red and one blue, are projected onto a screen through a parallax barrier. As the light shines back through the polarizer, two offset images are created, which creates the visual cues that the brain interprets as depth. Credit: Optics Express.)
Polarization is one of the fundamental properties of light; it describes how light waves vibrate in a particular direction—up and down, side-to-side, or anywhere in between. Sunlight, for example, vibrates in many directions. To create modern 3-D effects, movie theaters use linearly or circularly polarized light. In this technique, two projectors display two similar images, which are slightly offset, simultaneously on a single screen. Each projector allows only one state of polarized light to pass through its lens. By donning the familiar polarized glasses, each eye perceives only one of the offset images, creating the depth cues that the brain interprets as three dimensions.
The two-projector method, however, is cumbersome, so optical engineers have developed various single projector methods to achieve similar effects. The parallax barrier method, for example, succeeds in creating the illusion of 3-D, but it is cumbersome as well, as it requires a combination of rear projection video and physical barriers or optics between the screen and the viewer. Think of these obstructions as the slats in a venetian blind, which create a 3-D effect by limiting the image each eye sees. The South Korean team has developed a new way to achieve the same glasses-free experience while using a single front projector against a screen.
(The experimental setup of a proposed glasses-free 3-D theater experience is shown, with the projector in the familiar front position, creating 3-D images. Credit: Optics Express.)
In their system, the Venetian blinds’ “slat” effect is achieved by using polarizers, which stop the passage of light after it reflects off the screen. To block the necessary portion of light, the researchers added a specialized coating to the screen known as a quarter-wave retarding film. This film changes the polarization state of light so it can no longer pass through the polarizers.
As the light passes back either through or between the polarizing slates, the offset effect is created, producing the depth cues that give a convincing 3-D effect to the viewer, without the need for glasses.
The team’s experimental results reported today show the method can be used successfully in two types of 3-D displays. The first is the parallax barrier method, described above, which uses a device placed in front of a screen enabling each eye to see slightly different, offset images. The other projection method is integral imaging, which uses a two-dimensional array of many small lenses or holes to create 3-D effects.
“Our results confirm the feasibility of this approach, and we believe that this proposed method may be useful for developing the next generation of a glasses-free projection-type 3-D display for commercial theaters,” notes Lee.
Sadly, they still have more experiments to do, and it could be a few years yet before this technology is actually in use at your local theater. Still, it’s an interesting prospect. While the content and use of 3D is still up to the filmmakers, I imagine that cheaper display tech with the ability to appeal to a wider range of people would encourage filmmakers to be more dynamic with it, making 3D films worthwhile.