April 14, 2009 Gizmag has talked previously about the difference between stereoscopic and autostereoscopic 3D systems. To quickly refresh your memory, the former involves slipping on a dorky pair of glasses, which can end in headaches, while the latter you simply watch, without the need for any extra eyewear. A number of companies has invested considerable resources into developing autostereoscopic 3D TVs, confident that they will be the “next big thing.” Gizmag examines some of the best 3D TV design concepts out there, in an attempt to sort what's truly possible from what's pie in the sky.
University of Arizona’s rewriteable holographic display
Many of the holographs that surround us – such as on phone batteries or credit cards, for example – are made from photopolymers, materials that record laser light and display it so as to create an illusion of depth from certain angles. Photopolymers have a large storage capacity and can sustain an image for a prolonged period of time - highly attractive qualities in 3D technology. In the past, however, photopolymers haven't been used for television because they can only display the image that was originally encoded, which is why they work so well for bank notes and batteries. In February’s Nature magazine, Dr Nasser Peyghambarian outlined a rewriteable holographic display made from photorefractive polymers, the photopolymer’s more useful cousin.
Photorefractive polymers possess many of the traits of photopolymers. They can hold a large amount of data and display an image for an extended time and up to three hours in the dark. Unlike photopolymers, photorefractive polymers can be erased and rewritten with a new image, making them capable of producing basic animation.
The University of Arizona’s prototype holographic screen is 10 cm x 10 cm, and can record and display a new image every few minutes. The university research team hopes that eventually the display will provide television-quality pictures – which would still require great leaps in size, image quality, and speed.
Dr Peyghambarian says: “At present, the picture is effectively static, because it takes two minutes to write each new image. To get into the area of 3D movies and videos, we would need to write the information much faster - dozens of images per second. That's very possible, but we have to make the material respond much faster … We're talking about the next two to five years to work on these. I think we've already cleared the big hurdle - the quantum leap."
Dr Peyghambarian’s team claims that holographic TVs based on their technology could hit shelves within 10 years.
Philips and WoWvx
Electronic giant Philips’s WoWvx displays works on multiview lenticular lens technology. In the 2D-plus-depth format, pixels are bundled with information that indicates their depth, using 256 grayscale shades. A microlens in front of the LCD panel then uses that information to provide nine different views for each pixel, projected to various viewing angles.
This set-up ensures that each eye receives a slightly different picture, which is interpreted by the brain as a depth cue. The different views for each pixel also ensure that viewers are relatively free to move, reducing the “sweet spot” phenomenon that plagues less sophisticated systems. The 2D-plus-depth format only increases the bandwidth of the signal by 5-20%, which is unlikely to be seen as much of a hurdle for the industry.
Philips has been demonstrating the WoWvx systems at expos for a few years now, showing off the dynamic color and large screen sizes. The last one was 52 inches, with full HD 1920×1080 resolution (although the linear resolution takes a hit when presenting multiple views). Forty-two-inch 3D displays are already on the market.
The shape of the future
Most other companies interested in 3D TV, such as Samsung and Holografika, are working on models similar to Philips, and ignoring laser-recorded holographs as a display medium. This means if 3D TV launches onto the consumer market before 2020, it's likely to be based on multi-angle pixel projection. The more experimental 3D technologies, such as Dr Peyghambarian’s and the projector-based Cheoptics360 system are most likely to find selective applications in medicine, the military, and engineering.
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