By Patricia Daukantas

The weather outside the Baltimore (U.S.A.) Convention Center has been varying wildly, from warm and summery to cool and rainy. Indoors, however, the atmosphere of the CLEO:2011 conference was steadily abuzz with exciting applications of the latest photonics technologies.

Ultraviolet LEDs Can Disinfect Water

Although CLEO is primarily a laser conference, some tracks focused on other photonics technologies, such as photovoltaics and quantum computing. Following a joint symposium on semiconductor ultraviolet (UV) lasers and LEDs, a session reviewed several practical applications of UV LEDs.

One task for which these devices are particularly suited is the removal of harmful germs and other contaminants from drinking water. Gordon Knight, a research manager at Trojan Technologies (Canada), explained that UV light penetrates the cell membranes of bacteria, viruses and protozoa and permanently alters their DNA so the critters can’t reproduce and infect humans. UV rays can also break down organic contaminant molecules, as long as the molecular absorption spectrum matches the output of the UV sources.

Water treatment specialists are primarily interested in the UV-C spectrum (200 to 280 nm), in which the peak absorption spectrum of germ DNA falls, Knight said. The industry’s workhorse has been the low-pressure mercury arc lamp, which has a strong emission peak at 254 nm. However, solid-state UV sources could be more energy-efficient and could maintain their steady output for five times longer than the mercury lamps.

Although some technical challenges remain in the development of UV-C LEDs--namely, cost and the need to boost individual chip output above 5 mW--Knight is confident that these sources will provide efficient instant-on operation for future water treatment devices, both in municipal plants and perhaps even in household-sized systems.

IARPA: An Opportunity, Not a Misspelling

You’ve heard of DARPA, but what about IARPA? The Intelligence Advanced Research Projects Agency, a new branch of the U.S. government’s spy agencies, recently started searching for “high-risk, high-payoff” research programs to boost America’s intelligence-gathering efforts.

According to IARPA official Michael C. King, the agency is especially interested in significant advances in techniques to gather biometric data from distant, moving human subjects. Successful proposals require not just a good idea, but also a capable leader to guide the research project. One U.S. team followed King’s talk with a discussion of their own technique for so-called “standoff biometric identification” of people. According to Brian C. Redman of Lockheed Martin (U.S.A.), Fourier transform profilometry involves bouncing fringes from an 808-nm laser off the subject, capturing it and its two-dimensional fast Fourier transform, then doing an inverse transform and merging it with the original data. The laser pulses are eye-safe and, with a duration of 100 microseconds, short enough to freeze motion at a brisk walking speed of 1.5 m/s. The near-infrared light can even “see” through most sunglasses, Redman said.

Applied optics, Biomedical optics, CLEO/QELS, Energy, Lasers, Lasers, CLEO, OSA, Photovoltaics lasers, cleo, the optical society, optics & photonics news, quantum computing, biomedical optics, photovoltaics

By Patricia Daukantas

Every scientific advancement has a story behind it. Telecommunications fibers and optical coherence tomography (OCT) are no different. Donald Keck and James Fujimoto--the first two CLEO:2011 plenary speakers--did a great job of telling those true tales.

Donald Keck, a retired Corning Inc. (U.S.A.) scientist who participated in the development of the first low-loss optical fiber, attributed the telecom boom to a “syzygy” of rapid-fire technological developments four decades ago. In addition to that first practical fiber, the earliest computer-network experiments, the room-temperature laser chip and the computer chip all appeared between 1969 and 1971.

Evoking the original notion of the laser as a “solution looking for a problem,” Keck drew chuckles by reminding the audience of schemes for laser cutting of trees, laser-made nipples for baby bottles and Arthur Schawlow’s “laser eraser” for typists. Early proposals for laser telecommunications--by sending light beams down 2-in.-wide coaxial cables--were not much more practical.

Fortunately, British government researchers asked Corning for help in creating glass fibers with attenuation below 20 dB/km, at a time (1966) when the best silica fiber suffered from signal loss of 1,000 dB/km. Drawing upon glass research from the 1930s to the 1950s, Keck and his Corning colleagues started tracking down and eliminating the sources of optical loss in fiber.

Their initial fiber-drawing equipment was crude--including a household vacuum cleaner--but effective. When Keck tested the first fiber with a loss of only 17 dB/km, he was so impressed that he wrote in his lab notebook, “Whoopee!” However, in 1970 an Applied Physics Letters reviewer initially rejected the Corning team’s paper because, Keck said, “it lacked believability.”

Today’s single-mode fibers fulfill Keck’s 1972 prediction of operation with losses of 0.2 dB/km or less at the 1,550-nm wavelength. Progress in telecommunications has come rapidly, especially after the 1984 court-ordered breakup of the old Bell-System AT&T, which created “a lot of fiber-hungry ‘baby Bells,’” Keck said. With the development of fiber that can bend around sharper corners without introducing losses, the industry is poised to use fiber in ways traditionally associated with copper wire.

OCT: Joining Optics and Clinical Science

OCT is a method of imaging using echoes of light--the optical analogue of ultrasound, said James Fujimoto of the Massachusetts Institute of Technology (U.S.A.). In terms of resolution and tissue penetration, OCT bridges the gap between ultrasound and confocal microscopy.

Although Michel A. Duguay and A.T. Mattick first suggested the technique in a 1971 Applied Optics article, the first demonstration of OCT, performed on a cadaver eye, was published two decades later, according to Fujimoto. Since then, progress has come rapidly, with the technique’s extension to living tissue and the commercial development of OCT equipment for clinical use. Today, spectral domain interferometric techniques have improved both the speed and sensitivity of OCT. High-speed CCD cameras and volumetric data-rendering techniques have added to OCT’s ability to track dynamic processes such as capillary blood flow.

OCT is now moving beyond ophthalmic procedures into the world of intravascular imaging, where the technique can identify unstable arterial plaques and guide the medical treatment of those dangerous blood-flow blockers.

Fujimoto said that there has been a huge increase in intravascular OCT procedures in the last three years. The development of tiny fiber-optic catheters and the Fourier-domain mode-locked (FDML) laser have helped make this possible.

Finally, Fujimoto drew the audience’s attention to one of this CLEO’s postdeadline papers, which reports a record imaging speed for OCT using a swept single-mode vertical-cavity surface-emitting laser (VCSEL). OCT promises to be an exciting technological field to watch in the near future.

Applied optics, Biomedical optics, CLEO/QELS, Fiber optics, Lasers, Lasers, CLEO CLEO, CLEO2011, lasers, laser, fiber optics, biomedical optics, Donald Keck, James Fujimoto, optics, photonics, Optics & Photonics News, Patricia Daukantas, OPN

By Patricia Daukantas

I can’t let my coverage of FiO/LS end without mentioning the wonderful talk that OSA Honorary Member Arthur Ashkin gave at the special symposium organized in his honor.

Ashkin, now 88 years old and retired from Alcatel-Lucent/Bell Laboratories (U.S.A.), pioneered the notion of moving microparticles with laser light, back in the days when lasers were the new thing on the lab bench. His work formed the basis for optical tweezers and, eventually, the atom-cooling and laser-trapping work that garnered three other OSA Honorary Members their Nobel Prize in 1997.

In his autobiographical speech, Ashkin--who still has traces of the accent of his native Brooklyn, N.Y.--showed his warm and sometimes mildly self-deprecating humor. Yes, he said, he holds degrees from “all these fancy schools” like Columbia and Cornell universities, but it took him seven years just to get his bachelor’s degree.

That wasn’t entirely of his own doing. As he entered Columbia, World War II was starting and the university, whose physics department had people like Sidney Millman, Willis Lamb and Polykarp Kusch, founded a radiation laboratory with, as Ashkin put it, “all this new equipment free from the government.” Millman taught the new undergraduate about magnetrons – “glass, brass and sealing wax” – and then Ashkin got drafted at age 19.

“I’m a sophomore, how important can I be to the war effort?” Ashkin asked rhetorically. But the folks at Columbia got him into the Army’s enlisted reserve, so that he could work as a staff member, and he eventually built a megawatt magnetron.

Once Ashkin got to Cornell as a graduate student, he said, he took no solid-state physics or optics courses. “All I took was nuclear physics because there were all these guys from Los Alamos [the Manhattan Project, which built the first nuclear weapons],” he said. He took the first quantum mechanics class taught by the then-future Nobel Prize winner Richard P. Feynman. Ashkin added: “The stories I could tell, if I had the time…”

Once hired at Bell Labs, he was told he could do anything he wanted to do, but he still ended up working on microwave tubes for a while. “At Bell Labs they wanted you to do great work, but you had to find your own way,” he said.

In the late 1960s, Ashkin attended a talk about “runners” and “bouncers,” or tiny balls moving around due to heating. That got him thinking about radiation pressure, and he started thinking about moving even tinier particles with the light from laser beams, and then experimenting in earnest.

By the time Ashkin was writing his first paper on the subject, he was wondering whether the laser beams could trap atoms, molecules and microscopic living things. “So I put all that into the paper and got credit for it,” he added. His first experiments with trying to move bacteria around killed them--he dubbed it “opticution”--but eventually he and his colleagues learned how to keep them alive while moving them with infrared beams.

You can read more about Ashkin’s pioneering efforts in a March 2010 feature article in OPN.

Like a good entertainer, Ashkin knows how to leave his audiences wanting more. He wound up his talk by saying that during his 15-year retirement, he has been experimenting with solar power, and he thinks he has found away of getting energy from the Sun more cheaply than burning fossil fuels.“I’m writing a paper for Science, and if I tell you about it they won’t publish it,” he concluded. “So stay tuned.”

The Newest OSA Honorary Member

At its meeting during FiO/LS, the OSA board of directors selected James P. Gordon as the Society’s newest Honorary Member. Regular readers of OPN may recall his article for the May 2010 issue of OPN--the special “Lasers at 50” issue--in which he described his work on the first maser with another OSA Honorary Member, Charles H. Townes.

2010-10 October, Applied optics, Biomedical optics, Frontiers in Optics, Optics history fio, optics history, optical manipulation, optical tweezers, optical history, lasers

By Patricia Daukantas

Halloween is the season of ghosts, goblins and vampires … so why not add some spooky quantum entanglements to the mix? On a cloudy, damp morning in Rochester (N.Y., U.S.A.), the plenary speakers at OSA’s 94th annual meeting, Frontiers in Optics, took the audience on a tour of Bell inequalities, wild biomolecules and other scientific treats.

This year’s Ives Medalist, OSA 2007 President Joe Eberly, used elementary trigonometric identities (remember those?) to demonstrate a seeming contradiction in a thought experiment about a polarizing interferometer. Eberly, a longtime professor at the University of Rochester, solved the conundrum by showing that the photons were entangled in what is now known as a Bell state.

Measuring degrees of photon entanglement is one of Eberly’s recent interests. He noted that Erwin Schrödinger introduced the notion of entanglement in 1935 -- and, 75 years later, scientists still don’t have a lot of quantitative answers about it. This is “a guarantee of permanent employment for a physicist,” he said, generating a ripple of chuckles among the audience.

One of the two winners of the American Physical Society’s Arthur M. Schawlow Prize, Henry Kapteyn of JILA (University of Colorado, U.S.A.), paid homage to the award’s namesake. “It was clear he liked to point lasers at things and blow them up, and that’s mostly what we do,” he said. Fortunately, most of the high-energy (and soft-X-ray) lasers he talked about haven’t exploded, and he predicted that there are excellent prospects for generating hard X-ray laser beams from tabletop devices in the near future. His wife and co-prize-winner, Margaret Murnane of JILA, will speak at tonight’s APS Laser Science banquet.

Plenary speaker Steven Block, a professor of physics and biology at Stanford University (U.S.A.), took the audience on a tour of “riboswitches,” non-coding messenger RNA strands that control gene expression by changing their structure when they selectively bind to a signal molecule. In evolutionary terms, this is probably the earliest form of molecular control at the cellular level, but it was poorly understood until scientists could start manipulating the molecules with optical tweezers. (Attendees of CLEO/QELS 2010 in May might remember Block’s blues mandolin performance.)

The final plenary speaker, Alain Aspect of the Institut d’Optique (France), gave a history lesson on the Hanbury Brown and Twiss interferometry experiment of the mid-1950s and its relevance to modern-day quantum optics.

Checking the Efficacy of Breast-Cancer Therapy

Can oncologists deduce the efficacy of breast-cancer treatment as early as one day after the start of chemotherapy? According to Albert Cerussi of the Beckman Laser Institute (U.S.A.), this can happen, thanks to a technique called diffuse optical spectroscopic imaging (DOSI).

Traditional “adjuvant therapy” for breast cancer calls for surgery first, followed by a round of chemotherapy. Oncologists are now moving to “neo-adjuvant therapy,” in which the chemo comes first -- making it even more important to monitor the patient’s response to the powerful drugs.

DOSI works in the near-infrared window of 650 to 1,000 nm; those wavelengths penetrate tissue relatively well, although the photons take a “random walk” through the tissue (hence the “diffuse” part of the imaging). Instead of getting the black-and-white patterns of a traditional mammogram, DOSI provides spectral information about tumor biomarkers such as oxygenated and deoxygenated hemoglobin.

Researchers first studied DOSI at the midpoint of chemotherapy, when oncologists usually assess the patient and decide whether to switch therapies. But the researchers from Beckman and the Chao Family Comprehensive Cancer Center (both part of the University of California at Irvine) found that they could detect changes in the biomarkers one week and even one day after the start of chemotherapy.

According to Cerussi, scientists are even studying whether the technique could predict whether chemo will help a particular patient even before the treatment starts, but they are still trying to understand the biological process behind that. In the near future, researchers will look for additional biomarkers, shrink the size of the equipment, and join a clinical trial involving four other cancer centers.

(Note to readers of OPN’s Twitter feed, @OPNmagazine: Cerussi’s talk was the one I chose out of eight simultaneous invited talks at the start of the afternoon sessions. It was a tough call -- the other topics included luminescent solar concentrators, laser refractive surgery for cataracts and long-term monitoring of buried fiber-optic cables.)

Industrial Physics Forum

This event, sponsored by the Corporate Associates of both OSA and the American Institute of Physics, drew large crowds to several talks -- particularly the one by quantum cascade laser pioneer Federico Capasso of Harvard University. On Monday, the forum covered a range of biomedical and environmental applications of lasers.

An Earth-observing lidar satellite called CALIPSO (for “Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations”) has been in orbit since April 2006, and Carl Weimer (Ball Aerospace, U.S.A.) reviewed its ongoing engineering and science results.

As I described in an OPN article last year, CALIPSO is part of an “A-Train” of environmental satellites in the same orbit, with roughly 15 minutes of spacing between them. Its dual-wavelength (532 and 1,064 nm) lasers collect data in a 70-m-wide “curtain” from ground level to about 40 km altitude.

So far, the satellite has collected 6.6 terabytes of data from 2.6 billion laser shots, Weimer said. Its estimated particle sizes within cloud distributions provide important input for scientists’ models of global atmospheric circulation.

The Industrial Physics Forum is concluding this morning with sessions on lasers’ applications in metrology and other “frontiers of physics” areas.

The Day Ahead: Tuesday

This afternoon, brand-new OSA Honorary Member Arthur Ashkin will speak first at a symposium honoring his pioneering work with optical tweezers. The FiO/LS exhibit hall will open, and OSA student chapters will kick off their lesson plan competition. Two other events of particular interest to young professionals are a public-policy forum and the Minorities and Women in OSA (MWOSA) tea. Finally, we’ll all learn who won the OSA officer elections for 2011.

2010-10 October, Applied optics, Biomedical optics, FiO/LS, Lasers OSA, university of rochester, fio, biomedical optics, industrial applications, Patricia Daukantas, the Optical Society, quantum entanglement, CALIPSO, LaserFest

By Patricia Daukantas

A Cornell University (U.S.A.) scientist specializing in on-chip nanophotonics devices has won a $500,000 “genius grant” fellowship from the John D. and Catherine T. MacArthur Foundation.

OSA Fellow Michal Lipson, associate professor of electrical and computer engineering at Cornell, is one of 23 award recipients in diverse fields ranging from astrophysics to sculpture, theater and jazz. MacArthur Fellows receive $500,000 over five years with no strings attached.

The 40-year-old Lipson received the award for “working at the intersection of fundamental photonics and nanofabrication engineering to design silicon-based photonic circuits that are paving the way for practical optical computing devices,” according to the foundation’s website. She was named an OSA Fellow in 2008 for “outstanding contributions to the field of silicon nanophotonics, including the development of high-bandwidth modulators and low-power nonlinear optical devices.”

The MacArthur Foundation has put a brief biography and video of Lipson online. I wrote about her work in the November 2006 Scatterings column (four-wave mixing within a broadband light amplifier) and also in January 2008 (a microfluidic device that used light to sort tiny particles).

2010-09 September, Applied optics, Biomedical optics, OFC/NFOEC nanotechnology, awards, OSA Fellows, women, photonics, silicon photonics

By Patricia Daukantas

Most molecular biologists stare down at throngs of their tiny subjects the way an aerial photographer captures a large pack of runners at a marathon. Steven Block wants to focus on a single molecule, just like zooming in to study the guy who broke out of the pack to win the marathon four times.

That’s how Block, a professor of both biology and physics at Stanford University, set the stage for his Wednesday morning CLEO plenary talk on single-molecule biophysics with optical tweezers. I’m not an expert on biology by any stretch -- even my high-school biology class is sadly out of date now -- but I’ll try to convey what he said as best I can.

RNA polymerase, the enzyme that produces RNA, is a sophisticated nanomachine, and scientists would like to know how it works. Humans have three or four kinds of RNA polymerase; it’s the stuff that makes our cells differentiate themselves by function, even though each chromosome has the same DNA. On the scale of proteins, RNA polymerase is pretty big -- about 3,300 amino acids -- but on the scale of things in general, it’s pretty small -- roughly 10 nm big.

Optical tweezers are “the closest thing humans have made to a tractor beam,” Block said after showing his grad-school-days video of a single bacterium stuck in an optical trap. His experiments with then-grad-student Will Greenleaf and colleagues, as I understand them, involved setting up two tiny dielectric spheres in side-by-side traps and stretching a single DNA molecule back and forth between them. They did this in order to study riboswitches, which are non-coding messenger RNA (mRNA) strands that control gene expression by changing structure when they selectively bind to a molecule. More experiments are forthcoming, even though Greenleaf is now a postdoc at Harvard University.

David Awschalom, the QELS plenary speaker from the University of California at Santa Barbara, talked about something else that’s darned tiny: single electron spins in semiconductors.

Much like photons, electron spin ensembles exhibit coherence in doped semiconductors. Much research into semiconductor spins has been done with low-temperature ensembles, Awschalom said, but tremendous progress has been made over the last five years into the study of single spins in solid-state matter.

Diamond -- that glittering crystal of carbon -- is a CMOS-compatible (both p- and n-type) semiconductor with remarkable thermal properties. Awschalom and his colleagues study synthetic diamonds with certain impurities called nitrogen-vacancy centers, in which two neighboring points of the carbon crystal lattice are replaced by a nitrogen atom and a gap with no atom. (Diamond gemstones with many of these impurities look yellowish.)

Again, the way I understand these experiments, the team shone polarized light through a diamond at room temperature and used a confocal microscope to spatially map the photoluminescence pattern and thus measure the single spins. In a paper published last December in Science, the team described how these single spins can flip on the order of 1 ns, which is about five times faster than the RAM in a modern desktop computer operates. Paradoxically, performance improves with increasing temperature -- not the way conventional electronic devices work.

Arrays of these tiny spins within diamonds could have many uses in quantum computing and communications -- and many other kinds of defects in diamonds have yet to be explored. To keep up with Awschalom’s research group, check out http://www.physics.ucsb.edu/~awschalom.

2010-05 May, Biomedical optics, CLEO/QELS, Lasers, Lasers, CLEO cleo, cleo10, cleo/qels, laserfest, biomedical optics, molecular biology, dna, optical tweezers, optical manipulation, diamonds, semiconductors

By Patricia Daukantas

OSA Fellow Jim Wynne could be resting on his laurels for his role in developing laser ophthalmic surgery. Instead, he’s working on a new idea: using lasers to excise dead tissue from the wounds of burn victims.

Wynne, who works at IBM Corp.’s Thomas J. Watson Research Center, attended yesterday’s laser exhibit and demonstration on Capitol Hill in Washington, D.C. He and a Maryland ophthalmologist, Sonny Goel, were there to discuss laser eye surgery techniques such as laser-assisted in situ keratomileusis, or LASIK. As I recounted on this blog a few months ago, Wynne discovered the excimer laser’s ability to remove tissue cleanly without damage to the surrounding tissues, and that realization led to the wonders of ophthalmic refractive surgery.

For years, Wynne and his tennis buddy, dermatologist Jerome Felsenstein, have been batting around the idea of using a laser to debride the charred, dead layers of skin from the wounds of severely burned people. Currently, surgeons need to do this with a scalpel. Wynne and the dermatologist were trying to figure out how to get the advantages of extremely clean tissue removal without making the procedure take way too much time.

The answer, according to IBM’s recently filed patent application, is to use two ultraviolet lasers in a sterile, self-terminating procedure. One laser, operating at 308 nm, would act like rough sandpaper and remove a lot of the dead tissue quickly. The second, with a wavelength of 192 nm, would carefully clean off the last little bit of dead tissue and stop “when it hits salt water” or living tissue, Wynne said. (As he explained, the 192-nm light is close to a strong absorption line of chlorine ions, so when the light encounters the slightly salty liquid of living tissue, the energy goes into changing the Cl^– ions into neutral Cl atoms instead of heating the proteins in the skin.)

Wynne stressed that there’s one major caveat: This technique has not yet been tried on living animals (including people). But he showed me photos of an experiment performed on pigskin from a butcher shop. Wynne and his colleagues burned sections of the pigskin to a crisp with a blowtorch, and then they used the two lasers to remove the blackened surface of epidermal tissue and reveal the non-charred layers underneath. According to Wynne, the animal studies cannot be done at IBM, so he’s working out a partnership with one of the trauma surgeons at Brigham and Women’s Hospital in Boston (Mass., U.S.A.). They’re still seeking funding and equipment.

Wynne hopes that this technique – if it turns out to work on living patients, which is still not a given – could improve treatment of wounded soldiers in the field. The mobile medical unit could take off the necrotic outer layers of tissue before infections and fungi take hold, and then the patients could be airlifted to a burn center for skin grafts and treatment of their other injuries.

Finally, Wynne pointed out with pride this article from Ocular Surgery News, which provides compelling evidence that the benefits from LASIK and photorefractive keratectomy (PRK) are not just cosmetic: for members of the U.S. armed forces, who can’t wear contact lenses on the battlefield, the procedures mean a chance at a career track closed to the nearsighted – and can be life-saving for soldiers captured or caught on the battlefield without their eyeglasses.

It was great to meet Jim Wynne in person and pick up on his enthusiasm for doing science and inspiring others to pursue science. Since 1990, Wynne has been IBM’s program manager for local education outreach, and for most of that period he’s been getting IBM employees and high school students to volunteer at family science programs aimed at third- through fifth-graders. We wish him all the best with these educational efforts and look forward to hearing more about the laser-debridement experiments in the future.

2010-04 April, Biomedical optics, Lasers, Ophthalmology fellows, laserfest, lasers, opthalmology, surgery, biomedical optics, laser ophthalmic surgery

By Patricia Daukantas

Three physicists have figured out how to recreate a famous X-ray-diffraction experiment with a laser and other simple equipment. Their goal is to enable undergraduate students to follow in the footsteps of a chemical physicist who helped to decode the structure of DNA.

Rosalind Franklin (1920-1958), a young British scientist, took the famous X-ray diffraction image that was critical to identifying the structure of DNA as a double helix. Heidrun Schmitzer, Dennis Tierney and Gregory Braun of Xavier University (Cincinnati, Ohio, U.S.A.) include Franklin in their undergraduate course for non-majors on “Women Who Shaped Physics.” Featured scientists in the course include Marie Curie, Lise Meitner, Jocelyn Bell Burnell and Maria Goeppert-Mayer.

In their poster paper at this week’s American Physical Society March meeting in Portland, Ore. (U.S.A.), Schmitzer and her colleagues described the classroom experiment, which requires only simple tools: a red laser and the spring from a retractable ballpoint pen. Shining the laser beam through the spring projects a diffraction pattern strikingly similar to Franklin’s famous image. See the Xavier group’s photo of diffracted light and compare it to the X-ray image from 57 years ago (and an accompanying mathematical analysis).

By comparing the geometry of the pen spring to the diffraction pattern of the light, and then studying the Franklin X-ray image at its original size, the students “can determine the angle, pitch and radius of the DNA molecule, just like Rosalind Franklin,” Schmitzer wrote in the abstract.

Last night I did a quick trial of this with a spring from an old pen, my cats’ favorite laser pointer and a darkened room. Unlike Schmitzer, I did not block the bright center maximum with anything, so my result wasn’t as visually stunning. But I could see some evidence of the “X” pattern with faint characteristic stripes. I suspect that, with a bit more equipment and refined technique, this could make a stunning classroom demonstration.

2010-03 March, Biomedical optics, Optics history education, lasers, optical history, dna, american physical society, aps, physics, biomedical optics

Posted by Christina Folz, OPN Managing Editor 

I recently heard from OSA Fellow Pablo Artal about his cool blog, Optics Confidential. Artal is a topical editor of JOSA A and a professor at Murcia University in Spain. His blog is presented in a Q & A format. Artal answers confidential questions from graduate students about optics, science, technology, ethics, and more. Although much of the content is focused on Artal's own research and interest areas (visual and biomedical optics), he also provides general advice on how to give a good scientific presentation, for example, or how to ensure that your work is correctly cited. Check it out! 

2008-11 November, Biomedical optics social networking, social media, blogging, osa, biomedical optics, vision, ethics

By Patricia Daukantas

Optical technologies such as laser scanning confocal microscopy (LSCM) and multiphoton excited (MPE) fluorescence microscopy have given researchers wonderful new ways to image live cells and biological tissues. Today the Nobel Prize in Chemistry went to three scientists who found something for these state-of-the-art microscopes to see.

Back in 1962, Japanese cell biologist Osamu Shimomura of the Marine Biological Laboratory and Boston University Medical School (both in Massachusetts, U.S.A.) first isolated the substance known as green fluorescent protein (GFP) from the Aequorea victoria jellyfish and discovered that it produced a fluorescent glow under ultraviolet light. American biologist Martin Chalfie of Columbia University (New York, U.S.A.) showed that GFP could act as a luminescent “tag” that traces biological phenomena. American biochemist Roger Y. Tsien of the University of California at San Diego (U.S.A.) studied how the fluorescence mechanism of GFP works and extended the phenomenon to other colors and other proteins.

In the June 2003 issue of OPN, Paul Campagnola and William A. Mohler explained how GFP works: “[T]he gene that encodes for it can be linked to the gene of virtually any cellular protein of interest. The resulting fusion is then placed in cells or a whole organism and the desired protein is expressed with the GFP label.”

Scientific American has a nice article explaining the significance of GFP, and in a statement, the president of the American Chemical Society, Bruce Bursten, said, “Green fluorescent proteins allow scientists quite literally to see the growth of cancer and study Alzheimer’s disease and other conditions that affect millions of people.”

At OSA conferences, I’ve heard many researchers describe how they used fluorescent proteins as part of their experiments to improve biomedical imaging. One example of this work is a “Scattering” published back in February 2008, describing a retinal flow cytometer. A quick search of Optics InfoBase reveals numerous articles on work involving GFP in such OSA journals as Optics Express and JOSA A as well as OSA conference proceedings.

Quantum dots are starting to supplant fluorescent proteins in biomedical imaging because of their longer lifetimes and increased flexibility. Nevertheless, GFP and its glowing-protein cousins will remain an important component of the biomedical imaging toolbox for years to come.

2008-10 October, Biomedical optics nobel, nobel laureates, nobel prize, biomedical optics