The Brave New World of Displays
by Stephen Atwood
I wish I had my very own holographic real-time display to enjoy. Wouldn't we all like that? Not so long ago, we could enjoy stereoscopic 3-D in only a few select venues or through the use of very specialized projectors. Today, we can easily purchase and set up a stereoscopic display and watch real-time content with it. The technology is still a little young in terms of the ergonomics but there is plenty of content available and several ways to get it into your home to enjoy it. But stereoscopic is not the same as truly immersive 3-D. To get to the next level you either need to find a way to directly convert matter to energy and back again in real time or you need something like a holographic display.
The first reported work directly on holograms appears to date back to 1947, when physicist Dennis Gabor developed the holographic method, and his company, Thomson-Houston in the UK, filed for a patent. Several sources say that his work was focused on electron microscopy and his efforts led to the discovery of electron holography, which did not involve visible light.
After the development of lasers in the early 1960s, people discovered ways to record holographic images on recording mediums by capturing the interference patterns of the laser light reflected off three-dimensional objects as compared to the reference laser light itself. These recordings could then be re-illuminated by lasers or later by inco-herent light sources to re-create the original images in 3-D as though they were floating in space. These are what most of us have seen and know today as holograms. You can find them in many places, sometimes even on your credit card. However, the holographic processes are generally fixed in time and usually involve only static images.
With this context, which to me seems very similar to the early days of still photography and stereoscopic cameras, I have been eagerly watching the industry, looking for signs that real-time holographic displays are about to emerge. And yes, I'll confess I'm being overly futuristic in even allowing us to use the term "Holographic TV" in this issue. But after speaking with several experts who are actively working in this field, I am convinced that we can at least begin to start thinking about this eventuality with, if nothing else, a little imagination tempered by some industry context.
Back in 2008, authors Hagen Stolle and Ralf Häussler (Information Display, July 2008) told us how you could construct a holographic projector using a spatial light modulator, but then revealed the grim realities about the need to render literally billions of pixels in real time to make a large-screen holographic projection display practical. In the same issue, authors Savas Tay and Nasser Peyghambarian discussed their work using Photo-Refractive (PR) polymers to store the images in an analog optical method. As long as the recording medium can retain the image long enough, and be erased fast enough, it can be used to make holographic images that change in real time. One advantage of analog image storage is that you do not inherently need to break up the image into digital pixels. This is similar to the early days of analog television when the video signal was written onto the phosphor screen just as it came out of the camera, avoiding the need for high-bandwidth digital image processing.
After 2008, things seemed to be pretty quiet for a few years. Then, in 2011, I attended an imaging conference where I heard about the work being done by Pierre-Alexandre Blanche at Arizona State University, which involved cognitive studies on 3-D vs. 2-D maps and making holographic displays with PR polymer recording mediums. In the article "Toward the Ultimate 3-D Display" in our February/March 2012 issue, Pierre reported his success in making demonstration holographic displays up to 17 in. with update rates on the order of a few seconds or less. This further fueled my enthusiasm for the subject.
So, here we are in the fall of 2012 and a group of authors from Shanghai Jiao Tong University in China and Virginia Tech in the U.S. report their discovery of a self-erasing holographic recording medium that could indeed become the foundation of a real-time display. Their Frontline Technology article titled "Real-Time Dynamic Holographic 3-D Display" describes how they have demonstrated the ability to create 3-D images from images rendered on a spatial light modulator, without the need for billions of pixels, and still create at least a concept demonstration of a real-time holographic display – i.e., a television, for example. But, in order for any approach like this to work, you still need to render a tremendous number of pixels very quickly.
To understand how big a challenge that would be, we contacted Dr. V. Michael Bove from the MIT Media Lab and asked him whether it would be possible to harness enough processing power to make such a holographic display work. We were pleasantly surprised to learn that it's not inconceivable, and maybe even practical in the next 5–10 years, as he explains in his Q&A interview with our own Jenny Donelan. Oh, there are a number of caveats, but after you read both of these articles I think you will come away with the same optimism I have.
By now you might realize this is our annual novel technology issue, where we put our usual skepticism aside to find new and unique topics. For this issue, we had help from the University of Washington's Brian Schowengerdt, who assigned the holographic piece mentioned earlier, as well as our next two Frontline Technology follow-ups from the highly successful Innovation-Zone exhibits at Display Week in Boston this year. The first is from author Nate Saal at Tactus Technology and is titled "Microfluidic Technology Enables New User Interface." Tactus has developed a method to make tactile buttons and physical surface features appear and disappear on the surface of a touch screen through the use of fluid pressure and pre-formed membranes. With this technology, Tactus can literally raise a fully functional tactile keyboard from the surface of a projected-capacitive touch screen to allow typing, then collapse the keys and leave the surface flat and smooth to work again as a touch surface. I was skeptical until I tried it; now I'm convinced this will see some mainstream applications in the near future.
The next article describes the development of a new user-interface concept called a Virtual Remote Controller (VRC). In their article, "Virtual Remote Controller Enables New Laser-Projection-Based Applications," the authors explain how they can use a ceiling-mounted camera and laser system to create an immersive virtual remote control system they call a "UI Robot." Their work shows the kind of imagination and creative thinking we like to encourage. They have several ideas for how to create practical applications from their concepts, but my first thought was about how many times I lose the remote for my TV. If my TV remote really becomes my own hand, maybe I'll be able to find it when I need it.
In the end, though, we come back into the world of TVs. Our Display Marketplace this month is written by contributing editor Paul Semenza and is titled "OLED and 4K x 2K: Oxide TFT Could Help Make Both Happen." In his analysis, Paul describes how two distinct high-end TV trends are emerging, one by way of full HD OLEDs in the 55-in. size, as were demonstrated at Display Week this year. The other trend is from the LCD camp, trying to build enthusiasm for Ultra-Definition (UD) 4K x 2K panels in a range of very large sizes. Both of these are high-end trends meant to spark new life, and yes, bring new margins into the TV consumer market. The UD trend has prob-lems from the standpoint of lack of infrastructure and standards, but like moths to bright LEDs, our industry cannot contain the urge to make more pixels and larger displays even if it means getting well ahead of the symbiotic content creation and distribution industries it needs to survive. Regardless of which trend you look at, a key part of the success may rely on the success of cxide TFT technology, specifically IGZO.
Needless to say, putting this issue together was a lot of fun – even if I had to use a conventional keyboard instead of a tactile touch screen and a 2-D LCD instead of a fully immersive holographic version. With all these great innovations to look forward to, I hope you will be able to get as excited about the future as I am. •