LME--laser makers meet industrial customers

Conard Holton   Associate Publisher, Editor in Chief   Laser Focus World   cholton@pennwell.com

The new Lasers for Manufacturing Event, organized by the Laser Institute of America (LIA) and held September 27-28 in Schaumburg, IL, exceeded expectations and promises to offer a new forum for laser manufacturers, integrators, researchers, consultants, and industrial users. The show, held in the Renaissance Convention Center Hotel, drew 67 exhibitors and over 800 attendees, exceeding the expectations of the organizer.

Peter Baker, executive director of the LIA, said the goal had been distilling what might be found at numerous other large North American trade shows where a laser exhibitor might see only a few interested attendees out of thousands, and where attendees might have difficulty learning about industrial laser processes and finding laser companies with products of interest.

The location in Schaumburg was a bit remote, but still only 20 minutes from O’Hare airport and easily accessible to manufacturing companies in the upper Midwest. Baker said it was fulfilling the mission of the LIA, which is to foster lasers, laser applications, and laser safety—not to mention spurring economic development.



In addition to free courses on laser basics, advantages, and safety, speakers such as Todd Rockstroh from GE addressed topics such as lasers in aerospace, automotive, and biomedical device manufacturing. Bill O’Neill, director of the Centre of Industrial Photonics at Cambridge University, gave an engaging talk on the impact of laser technology on additive manufacturing, describing the waste and inefficiency of most processes and inefficiency of supply chains (see photo). His description of additive manufacturing, including laser sintering and 3D printing, opened a few eyes to the potential for consumer products, personal electronics, displays, solar power sources, and much more.

In unusual optics, don’t discount the sphere

John Wallace Senior Editor Laser Focus World johnw@pennwell.com

When it comes to simple, imaginative approaches to optical design, the spherical mirror has not been left out. Or at least that's what I found when I came across two optical systems that, while very different, share the same basic configuration.

Both are designed to collect light from astronomical objects; both can scan large portions of the sky; and both have very large, fixed primary mirrors.

Their spherical primaries are symmetric about a single, central point; this is a higher degree of symmetry than that for a paraboloidal mirror, which is merely rotationally symmetric about its optical axis. Well, obviously, one might say. And so what, one might add.

But this allows the designer to build a system with an optical axis that pivots around the sphere's center -- meaning that the enormous primary never has to move, and that the rest of the optics can have a narrow field of view and yet cover a huge portion of the sky.

In the case of the Hobby-Eberly telescope in West Texas, the optics are diffraction limited. The primary is 11 x 9.8 m in size, with the optics being able to use a 9.2-m-diameter portion of the mirror at any one time. This telescope can access three quarters of the night sky (just imagine the pointing mechanism that would be required for a more-conventional 9.2 m ground telescope that could access that much sky).

















Hobby-Eberly telescope (Image: Marty Harris/McDonald Observatory)


In the case of the solar bowl, one 15-m-diameter example of which was built on the roof of a kitchen in the south-India town of Auroville, a solar collector in the form of a rod pivots about the center of the sphere. As long as the rod is pointed at the sun, all sunlight received by the sphere is collected by the bottom half of the rod. On sunny days, the Auroville solar bowl provides steam for cooking for 300 people. In another example, a 20 m bowl was built in Crosbyton, Texas in the late 1970s by Texas Technical University to power a 40 kW steam turbine.



















Auroville solar bowl (Image: http://www.auroville.org/research/ren_energy/solar_bowl.htm)


OK, enough optical geekiness for now. But if anyone knows of any other optical uses of this stationary-spherical-mirror configuration, let me know. (By the way, the 1000-ft-diameter Arecibo radio telescope in Puerto Rico also was based on this approach.)

Origami and photonics fold together

Gail Overton Senior Editor Laser Focus World gailo@pennwell.com

Did you know that an origami-based folding solar panel designed by Japanese astrophysicist Koryo Miura actually flew on a Japanese satellite in the 1980s and is the inspiration for modern solar sails and folded optics in space? It turns out that origami, the Japanese art of folding a single sheet of paper into fabulous three-dimensional designs, has come a long way in recent decades: not just in the complexity of the beautiful art structures that can be fabricated, but in the many everyday uses for origami--some of them directly applicable to the photonics industry.

IMAGE: Origami is more than just small folded planes or party favors. A mathematical equation can define how a single sheet of paper can be folded hundreds (and even thousands) of times to produce beautiful works of art, as well as scientific structures. (Courtesy www.langorigami.com)

In an eye-opening and compelling presentation given at the 2011 Stanford Photonics Research Center (SPRC; Stanford, CA) 2011 SPRC Annual Symposium held last week on the campus of Stanford University (Stanford, CA), Stanford University and Caltech alumnus Robert J. Lang enlightened the crowd on how mathematics plays a role in creating seemingly impossible works of art as well as useful scientific applications in the form of origami.

Lang, who has his own origami website at http://www.langorigami.com/, explains how "computational origami" became his passion in the design of Eyeglass, a Lawrence Livermore National Laboratory (LLNL) project to develop a folded optical mirror for a space telescope. The 5 m diameter Eyeglass prototype is a model for how a small, folded form using the concepts of origami could be unfurled once safely in space into a 100 m diameter telescope optic.



IMAGE: LLNL's 5 meter diameter prototype Eyeglass folded-optic mirror is based on computational origami principles. (Courtesy www.langorigami.com)

Lang's website illustrates how origami can be explained mathematically; he even provides a free origami simulation tool that you can download online and a program called treemaker that allows you to turn a stick figure of an object into a work of art by translating that stick figure into a series of peak and valley folds on one sheet of paper. Incredibly, there are mathematical rules that define a functioning origami design.

And thinking beyond art, you might explore how that airbag in your car is folded and how heart stents can be inserted as thin solid tubes and be expanded within the body into cylindrical mesh structures that keep blood flowing freely; the origami connection may surprise you!

Does LED lighting at night have bad effects?

John Wallace   Senior Editor   Laser Focus World   johnw@pennwell.com

Scientists have been talking for many years about how artificial lighting can cause poor sleep. To that, you might say, "So shut the lights off." But the scientists are talking about the disruption of our circadian (day/night) rhythm, which would last beyond the time the bedside lamp was turned off. Here are just a couple of news snippets about the effects of burning the midnight oil.

Melatonin suppression
A team of researchers from Israel, Italy, and the U.S. are now saying that the light emitted by a white-light LED suppresses melatonin in humans at a relatively high rate. Melatonin suppression is apparently not a good thing, causing "behavior disruptions and health problems," as noted by a University of Haifa press release on the study. This is because it disrupts the circadian rhythm.

The researchers compared three types of bulbs: white LEDs, metal-halide lamps (used in car headlights and outdoor lighting), and high-pressure sodium (HPS) lamps. Melatonin suppression is caused by blue light; HPS lamps, with their orange-yellow hue, were the controls in the experiment. The results showed that metal-halide lamps suppress melatonin at a rate more than three times greater than the HPS bulbs, while white LEDs suppress melatonin at a rate more than five times higher than the HPS bulb. The study, titled "Limiting the impact of light pollution on human health, environment and stellar visibility," was recently published in the Journal of Environmental Management.

But research the easy way doesn't work
Another study, recently conducted by the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute (Troy, NY) found that satellite images of outdoor lighting are unrelated to actual light levels reaching the eye--which challenges previous studies linking areas on satellite images of bright outdoor lighting with increased incidences of breast cancer.

"After shift work was identified as a probable carcinogen by the World Health Organization, some studies were published that claimed a statistical association between light at night and the incidence of breast cancer. However, these studies relied on satellite photometry and subjects' self-reports of bedroom brightness as measures of light exposure. None of these studies employed actual light measurements at the eye," said LRC Director and principal investigator Mark Rea. "Before statistical associations between light at night and disease can graduate to a cause and effect relationship, it is necessary to measure the light as a potential causal agent." This apparently can't be done from space.

"It is important to note, however, that these findings do not undermine the foundational data using animal models that link melatonin suppression by light at night and cancer risks, nor does it contradict the statistical association between shift work and breast cancer risk in humans," add d Rea.

Dark sky at night, retiree's delight
A couple of years ago, a group called the International Dark-Sky Association (IDA; Tucson, AZ) issued a statement noting that "the rapidly expanding use of bluish-white outdoor lighting threatens visibility at night and jeopardizes the nocturnal environment worldwide." The statement specifically referred to LED-based outdoor lighting.

The IDA defines blue light as any light with a wavelength shorter than 500 nm, and says that lamps emitting blue light increase glare and compromise human vision, especially in the aging eye. "Short-wavelength light also increases sky glow disproportionately," states the IDA. "In addition, blue light has a greater tendency to affect living organisms through disruption of their biological processes that rely upon natural cycles of daylight and darkness, such as the circadian rhythm."

Rayleigh scattering, which occurs much more strongly at short wavelengths, is a hindrance to astronomers. Apparently, it's the bane of old people too.

What, me worry?
I believe in safety (seat belts were kind of a nice invention, I think). But I also suspect that a cup of evening coffee has a far greater impact on sleep than whether a nearby light bulb is a warm or a cool white. I believe that the increased energy efficiency of LEDs will be of great benefit in many ways. So, please join me in giving a boost to the beleaguered LED light bulb -- switch to decaf.

Downhole photonics

Gail Overton   Senior Editor   Laser Focus World   gailo@pennwell.com

I was reading an article this week in the July 2011 issue of Physics Today on natural gas fracking called "Shale-gas extraction faces growing public and regulatory challenges." It's fascinating to me that horizontal drilling, blasting, and high-pressure fracking chemicals loosen the rock thousands of meters below ground, liberating the natural gas and forcing it to the surface. Though opinions may differ on the environmental soundness of natural gas fracking and other oil-extraction methods such as steam-assisted gravity drainage (SAGD) and tar sands conversion, one thing is certain: the thirst for energy means that ALL sources will continue to be exploited until truly "sustainable" energy generation methods are widely deployed (or until the atmosphere becomes so toxic that you can't breathe).

To minimize environmental issues and improve yields and drilling safety in fossil-fuel extraction (NOTE: I never have been a fan of the term "fossil fuel" since there is conflicting research that says perhaps the earth's crust itself generates oil--see "Laser heating shows that petroleum could have non-dinosaur origins" in Laser Focus World's May 2010 issue), I'm all for using photonics in any way possible. For a review on downhole photonics applications and the tremendous strides that have been made in sending optics into one of the hottest, dampest, harshest environments on the planet, see "Downhole sensing puts fiber optics to the test" in our April 2011 issue.



IMAGE: A fiber-optic sensor is being loaded downhole to monitor temperature and pressure. Courtesy Intelligent Fiber Optic Systems (IFOS; Santa Clara, CA)

One of the fascinating aspects of downhole petroleum sensing that I neglected to cover in my recent article is the need to monitor seismic activity in both terrestrial and especially, marine environments; oddly enough, if you read the Physics Today fracking article you'll see that fracking has even been linked to earthquakes! Our sister media company PennEnergy covered a very interesting fiber-optic geophone that improves over electronic-based technology for downhole seismic monitoring. As the number of fracking sites increases throughout the United States, I certainly would like to know if there is a fracking/earthquake link. As a California native, earthquakes are a big deal and a big concern; any help we can get from photonics and optics in learning more about them is surely appreciated!

Prize for laser innovation

Conard Holton Associate Publisher, Editor in Chief Laser Focus World cholton@pennwell.com

The Berthold Leibinger Innovation Prize honors scientists and developers who make advancements in the field of applied laser technology. The 2012 call for entries--open to the international laser community--is accepting applications until December 31, 2011. There is no restriction with regard to the field of application.

In 2012, a select jury will award prize money of 30,000 euros for first, 20,000 for second, and 10,000 for third. In addition, the Future Prize of 30,000 euros is awarded for outstanding scientific research that lays the foundation of innovation. There is no call for applications for this prize. More information and entry forms may be found on the Berthold Leibinger Foundation website.

The prize winners in 2010 were:

1. Laser Based Luminescence Imaging of Silicon Bricks, Wafers and Solar Cells--by Thorsten Trupke, at The University of New South Wales & BT Imaging and Robert Bardos, BT Imaging

2. Two winners: Clinical Multi-Photon Tomography by Karsten König, JenLab, Germany; and UV Excimer Laser Technology--Key to Mass Production of Ceramic High Temperature Superconducting Tapes by Alexander Usoskin, Ralph Delmdahl, and Kai Schmidt at Bruker HTS and Coherent, Germany

3. Femtosecond Light Source Spanning from the Ultraviolet to Infrared by Majid Ebrahim-Zadeh, ICFO-Institute of Photonic Sciences, ICREA-Catalan Institute for Research and Advanced Studies & Radiant Light, Spain

The Future Prize went to Federico Capasso at Harvard University, USA.

If you feel you are making a significant contribution to applied laser technology, this prize is an opportunity to see your work acknowledged.