New Dimension Trends: Photonics Enters New Dimensions

Optics and photonics are everywhere. Not just in industrial settings or research environments or the medical arena. Everywhere. And with each new day, they are becoming more integral to how we live our lives – at home and at work, at the supermarket, the multiplex and probably even the county fair. Here we take a look at several areas in which photonics is making an impact and how the technology is evolving, and at what some of the barriers to more widespread implementation might be.

Flying off the screen

2010 will surely be remembered as the year that a group of lithe blue creatures stole the hearts of moviegoers everywhere as the 3-D spectacular Avatar rolled across the country and around the world.

If all goes well, it will also be remembered as the year that 3-D came to the home viewing market. A number of companies introduced 3-D capable televisions in 2010, including LG, Panasonic, Samsung, Sony, Toshiba and Vizio.

LG is just one of several companies that introduced 3-D capable televisions in 2010. Consumers may not be embracing the technology as rapidly as the industry would like, however. Courtesy of LG.

Consumers still aren’t entirely sold on 3-D television, though – because of a relative dearth of programming and also because of the price of the sets, which remains high. This is especially true in North America, where consumers have been trained to expect rapid price drops with new technology, said Paul Gagnon, director of North American TV Research with Santa Clara, Calif.-based DisplaySearch. Of the 3.2 million 3-D sets forecast to ship in 2010 – in the market research and consulting firm’s Quarterly TV Design and Features Report – only 1.6 million would be bought in North America.

Another discouraging finding: Sales of 3-D glasses in Western Europe remain low. In most countries there, fewer glasses are sold than sets, suggesting that many households have only the pair that came with the television. A healthy level would be closer to two pairs per set, DisplaySearch said. The current numbers point to the possibility that many consumers are simply “future-proofing,” or that they cannot buy premium sets without 3-D.

Wider availability of content, of course, would help to win over those currently on the fence about 3-D television. Panasonic understands this and has worked closely with DirecTV and ESPN, among other providers, to launch 3-D channels. At the same time, said the company’s Robert Harris at the Vision Show held in Boston last May, it has encouraged production of 3-D content by developing further end-to-end solutions: namely, an integrated twin-lens full-high-definition 3-D camera recorder.

In addition, a number of movies were released in 3-D Blu-ray this past holiday season – including the much-anticipated 3-D version of Avatar, which came bundled with Panasonic 3-D sets and Blu-ray players, and the 3-D Blue-ray of Alice in Wonderland, available exclusively with Sony 3-D hardware. (Also released in November: the very first 3-D Blu-ray porn movie. This is actually a good sign for the industry. Pornography has long been a major driver of technology change and adoption.)

Even as 3-D content becomes more widely available, however, 3-D television is competing with other platforms offering new formats for TV viewing: most significantly, connected televisions integrating the Internet into sets and set-top boxes. More than 40 million integrated television units were forecast to ship in 2010, with the number increasing to 118 million in 2014.

Lighting up the sky

Laser displays and laser light shows are used to entertain audiences everywhere, and in a wide range of contexts: from rock concerts and dance performances to clubs and raves, from family theme parks to the “Laser Pink Floyd” show at the local planetarium. Design and production of the shows are ever-evolving, as are the technologies and safety practices used with them.

Laser light shows are growing ever more sophisticated as the technology used for them continues to evolve. Courtesy of the International Laser Display Association. Used by written permission. All rights reserved.

Greg Makhov, president of Orlando, Fla.-based Lighting Systems Design, noted several trends on the technology side: for example, the advent of a low-cost, high-power blue diode laser. This has had an interesting evolution, he said, and, “on certain levels, kind of a seedy one”: Casio recently introduced a video projector based on a blue diode laser source. Hobbyists subsequently opened it up and found that it contained 24 diode lasers in an array – less expensive clones of other diodes, he said; it is not yet clear who the manufacturer is.

Since this discovery, companies have been buying up the Casio projectors, harvesting the diodes and using them for everything from laser pointers to laser displays. One company has taken the entire array, already collimated, and put it into a moving fixture.

The relatively low cost of these diodes has created a bit of a stir in the laser display industry, Makhov added. “Some people are frothing at the mouth because of the cost reduction.”

Sources used in laser displays are not just getting cheaper, though. They are getting smaller and more rugged. Coherent has been leading the charge with optically pumped semiconductor laser technology, which offers both small size and minimal technical requirements. Initially offering lasers in the green and yellow regions of the spectrum, the company expanded into the blue and eventually into the red.

The availability of these lasers is having a significant impact on the industry. Moving from large, very delicate ion laser sources to smaller, fan-cooled optically pumped semiconductor laser sources that can be plugged into the wall is changing how shows are designed, Makhov said. “Now you can literally put an entire laser show into the back of your car, and you can have multiple, discrete lasers instead of one big gun.” This is leading to much more creative displays.

Even as the displays grow more creative and sophisticated, the industry is increasing its focus on safety – especially with respect to audience scanning, a practice in which lasers are beamed into a crowd during an event. Audience scanning dates back to the 1970s, the early days of lasers in rock concerts. (The first instances may have been on Blue Öyster Cult’s “Agents of Fortune” tour in 1976. During these shows, a lighting engineer would shine a laser – a raw beam – onto Buck Dharma’s guitar. Dharma would then aim it at the audience as he played.)

Laser light displays that incorporate audience scanning have a proven safety record. Still, they are rarely seen in the US. Courtesy of the International Laser Display Association. Used by written permission. All rights reserved.

However, while the practice has grown ever more popular in the rest of the world – at clubs and raves, in particular – today it is rarely seen in the US. The reasons for this are twofold, said Patrick Murphy, executive director of the International Laser Display Association (ILDA). First, while the regulations governing the practice are largely the same the world over, they are more strictly enforced in the US than elsewhere. At the same time, there is a general culture of litigation and safety precautions in the States. Many who stage laser light shows fear the potential legal and public relations ramifications should an injury occur.

An average of only 2.5 incidents per decade have been reported in the past 30 years for shows using continuous-wave lasers for audience scanning. During this time, at least 110 million people have attended the shows. (Injuries have been reported for displays inappropriately using pulsed lasers – at a 2008 festival outside Moscow, for example.) Even conservatively accounting for 90 percent underreporting, that would be only 75 incidents over three decades, says Patrick Murphy of the International Laser Display Association (ILDA). Courtesy of ILDA. Used by written permission. All rights reserved.

Audience scanning is in fact possible within the maximum permissible exposure (MPE) established by the FDA. But the effect at these levels is relatively dim, while the increased beam divergence produces “fuzzy” beams with soft planes and cones of light. As a result, the overall experience can be considerably less exciting.

To address this, ILDA has proposed allowing optional “Level 2” audience scanning under specified conditions. This would permit brighter beams – up to 10 times the nominal MPE – in venues such as clubs and raves, where patrons already seek out higher risks, including loud music, alcohol and smoking.

The practice of “audience scanning,” in which lasers are beamed into the audience, is increasingly popular in the rest of the world but still rarely seen in the US. The International Laser Display Association has proposed a new category of audience scanning that it hopes will lead to more such shows in the States. Courtesy of the International Laser Display Association. Used by written permission. All rights reserved.

In return, Murphy said, venues would be required to post patron health warning signs (similar to those seen on thrill rides and in alcohol-serving establishments) and to employ additional laser safety measurements and procedures. Based on 30 years of laser show safety results, as well as patron-initiated avoidance procedures, ILDA believes that Level 2 scanning is safe on both an empirical and a scientific basis.

“The long-term goal is to have this concept recognized by standards and regulatory bodies,” Murphy said. Until then, as ILDA points out, Level 2 scanning can be used as an informal working procedure. “Those in charge of shows, such as club/rave venue owners and laser show producers, can together determine whether they are comfortable with the higher power and more stringent safety requirements of Level 2 shows. If so, then they can go ahead with such a show.”

The association believes that Level 2 will significantly improve safety with respect to current club- and rave-type shows, which are often 50 to 100 times the MPE. Murphy adds that anyone not comfortable with the higher levels – theme parks and family attractions, for example – can continue to produce Level 1 shows below the established MPE.

ILDA has not yet made any formal proposal regarding the two-level audience scanning. The association will likely do so at the 2011 International Laser Safety Conference, Murphy said.

Shimmering like Princess Leia

For most of us, the original Star Wars movie – released some 33 1/2 years ago – offered the first-ever glimpse of dynamic holography: In an early scene, the droid R2-D2 projects a shimmering, three-dimensional recording of Princess Leia imploring Obi-Wan Kenobi to aid in her struggle against the evil Empire.

Researchers have reported a three-dimensional holographic imaging technology that can be used for an array of applications. Shown here is principal investigator Nasser Peyghambarian with a refreshable holographic image of an F-4 Phantom Jet (detail, left) created on a photorefractive polymer at the University of Arizona College of Optical Sciences in Tucson. Courtesy of Norma Jean Gargasz/ UANews.

Unfortunately, in the decades since, we have seen little in the way of real technology matching the sort depicted in the movie. “Holographic stereography has been capable of providing excellent resolution and depth reproduction on large-scale 3-D static images,” Pierre-Alexandre Blanche and colleagues wrote in the Nov. 4, 2010, issue of Nature, “but has been missing dynamic updating capability until now.”

In a paper featured on the cover of that issue, the researchers – a team at the University of Arizona College of Optical Sciences led by professor Nasser Peyghambarian – described a holographic imaging technology that can record a three-dimensional image in one location and show it in another. The projection refreshes every two seconds and thus offers a 3-D moving image much like that seen in Star Wars all those years ago.

The technology, referred to as three-dimensional telepresence, does not require special eyewear such as 3-D glasses or any other auxiliary devices.

Rather, it takes advantage of a screen made from a novel photorefractive polymer; the Oceanside, Calif.-based company Nitto Denko Technical provided the polymer sample and media preparation. An array of cameras records images of an object from different perspectives and sends them to the hologram setup via an Ethernet connection – across the room or across the country. There, a fast-pulsed laser beam writes the information into the photorefractive polymer, each pulse recording an individual “hogel,” or holographic pixel.

Shown are pictures of a hologram recorded with the 3-D telepresence system. This technology is featured on the Nov. 4, 2010, cover of Nature. Courtesy of Blanche et al, Nature.

While the device reported in the Nature paper uses a 10-in. screen, the researchers are already testing a version with a 17-in. screen. Also, they have already demonstrated multicolor 3-D display devices – the device described in Nature presents in only one color – with a much faster refresh rate, which enables considerably smoother transitions between images. They noted that it won’t be long before they can incorporate these devices into the telepresence setup.

The researchers cited a number of potential applications of holographic telepresence, including advertising, updatable 3-D maps, entertainment and telemedicine. The latter requires improvements in both the 3-D display and the Internet communication technologies, Peyghambarian said in an e-mail. The display needs to be expanded from the current 17 in. to 6 to 8 ft, and in addition requires full color, and fast writing and display speeds. Telemedicine applications would also benefit from higher resolution.

To handle information delivery for such applications, the Internet communication component must be able to handle a data rate of several gigabits at low cost.

Work toward these goals is progressing rapidly, Peyghambarian said. With respect to the Internet communications component, he and the others on his team are focusing on access aggregation networks and trying to enable high-bit-rate access to users at low cost. At the same time, they are developing a packaged large-area 3-D optical holographic display with full color and fast response.