Frontiers in Optics 2008 (FiO), the 92nd Annual Meeting of the Optical Society (OSA), will be held from Oct. 19-23 at the Riverside Convention Center in Rochester, N.Y. FiO 2008 will take place alongside Laser Science XXIV, the annual meeting of the American Physical Society's Division of Laser Science.

FiO RESEARCH HIGHLIGHTS

Following are a few of the many technical highlights to be discussed at the meeting. Additional technical highlights are available here. Reality to Go: 3-D Virtual Reality on Mobile Devices

A Potential New Tool for Brain Surgeons

New Optics for Improved Solar Power Generators

Using Algae to Convert Sunlight into Biofuel

Highest Power Tabletop Laser Ever Built REALITY TO GO: 3-D VIRTUAL REALITY ON MOBILE DEVICES

If mere texting, talking, e-mailing and snapping pictures on mobile devices aren't enough to satisfy your data cravings, now there's the prospect of accessing and displaying 3-D virtual reality simulations and animations on them. New information architecture from researchers in Offenburg, Germany puts 3-D visualizations in the palm of your hand to make this possible.

By devising a novel information and communication architecture with optics technology, researchers created a new approach based on outsourcing to servers all the heavy number crunching required by computer animations and virtual reality simulations. After churning through it, the servers then provide the information either as stream (avi, motion JPEG) or as vector-based data (VRML, X3D) displayable as 3-D on mobile devices. Dan Curticapean and his colleagues Andreas Christ and Markus Feisst of Offenburg's University of Applied Science devised the approach.

"Since the processing power of mobile phones, smart phones and personal digital assistants is increasing- along with expansion in transmission bandwidth - it occurred to us that it is possible to harness this power to create 3-D virtual reality," says Curticapean. "So we designed a system to optimize and send the virtual reality data to the mobile phone or other mobile device."

Their approach works like this: Virtual reality data sent by the server to a mobile phone can be visualized on the phone's screen, or on external display devices, such as a stereoscopic two-video projector system or a head-mounted stereoscopic display. The displays are connected to the mobile phone by wireless Bluetooth so the user's mobility is preserved. In order to generate stereoscopic views on the mobile display screens, a variety of means can be used, such as a built-in 3-D screen or using lenticular lenses or anaglyph images viewed with special glasses having lenses of two different colors to create the illusion of depth.

The upshot of this new approach is improved realistic 3-D presentation, enhanced user ability to visualize and interact with 3-D objects and easier presentation of complex 3-D objects. "Perhaps most important," says Curticapean, "is the prospect of using mobile devices such as cell phones as a user interface to communicate more data with more people as an important component of mobile-Learning (m-Learning), given the ubiquity of mobile devices, particularly in developing countries."

Presentation FThM12, "3-D Mobile Virtual Reality Simulations and Animations Using Common Modern Displays," Thursday, Oct. 23, 12 p.m., Riverside Court Room, Rochester Riverside Convention Center

A POTENTIAL NEW TOOL FOR BRAIN SURGEONS

One of the primary ways of treating brain cancer is surgically removing the tumors. The risk of this sort of procedure is obvious -- it involves cutting away tissue from the brain, potentially severing nerve fibers and causing neurological damage. MRI and CT scans can reveal the extent of tumors, but only prior to surgery. These techniques rely on large instruments that cannot be used in the operating room, and during the operation the brain may relax and move, forcing surgeons to adjust where they are cutting to minimize the damage to the brain tissue.

During surgery, doctors make these adjustments by asking their patients to perform certain tasks while electrically stimulating parts of the brain bordering where they plan to cut. The electrical stimulation inhibits brain function in that region, revealing whether losing that tissue would cause permanent damage. Although slow, this is a good way to detect and protect critical areas of the brain.

Now Paul Hoy and his colleagues at the University of Southampton in England are developing a rapid and highly sensitive method for measuring brain function across the entire area during surgery. The method is based on observing blood flow in the brain. Active brain regions have increased blood flow, and this change can be observed by looking at light reflected off the brain because hemoglobin, the protein that ferries oxygen within the bloodstream, will absorb light differently depending on whether it carries oxygen or not.

Recently Hoy and his colleagues measured this signal on four people undergoing brain surgery and showed that their results agreed with the electrical stimulation. They hope that the technique will one day provide information quickly for neurosurgeons, and they are now collecting data that will lead to a clinical trial designed to test how effective the technique is.

Presentation FTuD3, "Optical Intraoperative Measurement of Function in the Human Brain," Tuesday, Oct. 21, 9:15 a.m., Highland D, Rochester Riverside Convention Center

NEW OPTICS FOR IMPROVED SOLAR POWER GENERATORS

A few years ago, the U.S. Defense Advanced Research Projects Agency (DARPA) launched its Very High Efficiency Solar Cell (VHESC) program. DARPA challenged the industry and the research community to make solar cells more efficient -- as measured by how well a solar cell converts the light it absorbs into electrical energy. The goal is to be able to provide soldiers in the field with inexpensive portable solar power generators -- the sort that would be no larger than a laptop and would be able to recharge that laptop in an hour or so.

The problem with making such small solar power generators is that even the most advanced solar cells available today are not efficient enough. The highest efficiencies demonstrated so far have been just more than 40 percent, but those demonstrations have taken place in carefully controlled laboratory settings and not with portable field units as the DARPA program calls for. Besides that, the most efficient laboratory cells rely on expensive-to-manufacture materials that cost some $50,000 to $70,000 per square meter. The sort of commercial solar panels you might buy today to have installed on your rooftop are much cheaper, but they are even less efficient, topping out at 16 to 17 percent. The DARPA program calls for efficiencies of 50 percent.

University of Rochester Professor Duncan Moore is part of a team reaching for DARPA's goal under the VHESC program. Their approach to achieving the higher efficiency involves using special coatings on solar cells that split light into colors like blue and red, which scientists estimate will increase efficiency by 50 percent. They then use different types of solar cell materials that each optimally absorbs energy from a different color light. Moore's research enhances this further by finding ways to intensify the light. In his Frontiers in Optics talk, Moore will describe how he is designing an optical cover for solar panels that concentrates sunlight -- much as a magnifying glass can concentrate sunlight enough that it can burn wood.

Presentation JWC3, "Optics for Solar Cells for Portable Power," Wednesday, Oct. 22, 5 p.m., Highland B, Rochester Riverside Convention Center

USING ALGAE TO CONVERT SUNLIGHT INTO BIOFUEL

Scientists at the University of California, Berkeley want to make micro-algae "less green." That is, they hope to modify the tiny organisms so as to minimize the number of chlorophyll molecules needed to harvest light without compromising the photosynthesis process in the cells. To that end, they have identified the genetic instructions in the algae genome responsible for deploying approximately 600 chlorophyll molecules in the cell's light-gathering antennae. The Berkeley researchers figure that the algae can survive with approximately 130 molecules.

Why go to this trouble? Researcher Tasios Melis argues that a larger chlorophyll antenna helps the organism survive in the wild but is detrimental to the engineering-driven effort of using algae to convert sunlight into biofuel.

The scientists want to divert the normal function of photosynthesis from generating biomass to making biofuels, that is, into products such as lipids, hydrocarbons and hydrogen. In this regard micro-algae are ideal because of their high rate of photosynthesis; they are perhaps 10 times more efficient than land plants. Melis says that the phrase "cellular optics" describes this general effort to maximize the efficiency of the solar-to-product conversion process.

Presentation JThB3, "Optical Properties of Microalgae for Enhanced Biofuels Production," Thursday, Oct. 23, 11:15 a.m., Highland A, Rochester Riverside Convention Center

HIGHEST POWER TABLETOP LASER EVER BUILT

Physicists at the University of Texas have built a tabletop laser that produces, at the present time, the largest peak power of any laser in the world: 1.1 petawatts (PW), or 1,100 terawatts (1.1 x 10^15 watts). A few (much larger) lasers have reached the petawatt level in the past (e.g. Livermore's NIF laser and Rutherford's Vulcan laser). The Texas laser, like the others, relies on chirping, a process in which a short laser pulse is stretched out, then amplified by a factor of a trillion, and then recompressed to a very short pulse size. In this case, the Texas laser delivers large energy (186-joule [J]) photons crammed into small time-frame (167 femtoseconds [fs]) bursts to achieve their high power. According to Texas scientist Erhard Gaul, the next goal is to produce 200-J energies packed into 150-fs pulses. Further on, peak powers of more than 100 PW might be possible. The immediate use for the Texas pulses is for studying the fusion of deuterium clusters and the production of particle acceleration using the immense electric fields produced when such a laser pulse passes through thin targets.

Presentation FWX3, "1.1 Petawatt Hybrid, OPCPA-Nd:glass Laser Demonstrated," Wednesday, Oct. 22, 5 p.m., Highland F, Rochester Riverside Convention Center

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Source: Colleen Morrison
Optical Society of America