By Patricia Daukantas
One uses optics to probe the molecular mechanisms of living cells. A second performs femtosecond time-resolved coherent anti-Stokes Raman scattering (CARS) measurements on single molecules. A third did a college-freshman project involving a vertical cavity surface-emitting laser.
These three up-and-coming scientists are all doctoral candidates in science and engineering and are all active in OSA and its student chapters. They’re also all women who recently told their stories to Jennifer Kruschwitz, a long-time OSA volunteer, as part of a campaign to increase the visibility of minorities and women, who are underrepresented in optics and photonics careers (as well as most other branches of science and engineering).
The first three women to get the Minorities and Women in OSA (MWOSA) spotlight are Ruby Raheem, Centre for Biomedical Engineering, University of Edinburgh, U.K.; Meredith Lee, department of electrical engineering, Stanford University, U.S.A.; and Desiré Whitmore, department of chemical and material physics, University of California, Irvine, U.S.A. All three scientists’ profiles are available at OSA’s Web site and more inspiring stories like theirs will appear in future months. Be sure to sign up for the monthly MWOSA newsletter if you haven’t already done so.
In other news, the journal Nature recently published an article claiming sexism within the particle physics community at Fermi National Accelerator Laboratory in Batavia, Ill., U.S.A. (Note that you will need to pay to read the full article unless you have a subscription to the journal.) The author, Sherry Towers, studied the careers of 57 researchers on one particle physics experiment and found that the women on the team did more of the maintenance work and got less of the glory (in the form of conference talks). The online version of the full Nature article includes a lively stream of comments on Towers’ findings and other issues concerning women in scientific careers; you can view the comments on the Web without purchasing the full news story. A preprint of the original article by Towers is at arXiv.org.
Posted by Christina Folz, OPN Managing Editor
This past Monday, the premier of New South Wales, the most populous state in Australia, proposed a law making it a serious crime to be in possession of—are you ready for this?—a laser pointer. I learned about the new law by way of this alarming blog post from the New York Times. Fortunately for all you professors out there, exemptions will be made for teachers, as well as construction crews, architects, astronomers and other scientists with reason to have a pointer. But for everyone else, possession of a handheld laser, depending on the laser’s power, could land a person in prison for up to 14 years if the proposed ban takes effect.
How did a device best known for punctuating lectures and bedazzling cats come to be treated like a firearm? The legislation follows a series of incidents in Australia in which aircraft pilots were distracted by a laser that was pointed at them by someone on the ground. The United States faced a similar spate of cockpit laser hits in 2005. Around that time, the Associated Press had reported that “governments could use lasers to blind pilots,” fueling speculation that laser pointers had, well, a substantial dark side. Richard Linke, OSA’s former director of science policy, helped to clear things up for the staff at OSA in February 2005, when he gave a lecture that explained the science behind the laser/plane panic. According to Linke, who is now the executive director of IEEE’s Lasers and Electro-Optics Society, a typical handheld laser probably wouldn’t blind pilots for more than a few seconds, although it could pose a danger by startling them.
Even when a laser pointer is shone directly into someone’s eyes at a short distance, most individuals will react by blinking or turning away within a quarter of a second, Linke says. Due to this aversion response, there is no realistic risk of eye injury from class 3A commercial laser pointers, which have an output power between 1 and 5 mW. Also, because the beam spreads with distance due to diffraction, the risk of injury decreases with increasing distance. When shone at a target one mile away, a typical laser pointer would have a “spot” size nearly 8 feet wide!
Anthony Campillo, OSA’s current director of science policy, agrees with Linke’s assessment. “Laser pointers will generally NOT cause permanent eye damage, unless one looks directly into a 20 mW green pointer at arm’s length,” he says. Rather, the main threat is caused by a “dazzle” effect, which causes temporary blinding similar to that from a lightbulb flash, or else panic resulting from the incorrect perception that the exposure is dangerous. “It’s not the laser pointer itself that is a danger but its misuse,” says Campillo.
OSA Fellow Emeritus Tony Siegman says that handheld lasers have even been marketed for search-and-rescue situations. Disabled hikers or lost sailors could use them to signal a plane for help. Siegman himself carries a green laser pointer in an emergency kit in his backpack when he goes on backcountry ski excursions around Lake Tahoe.
More Information
http://optics.org/blog/2008/04/panic_in_the_sky_1.html
http://www.equipped.org/lasers_airliners.htm
http://www.pangolin.com/resguide09c.htm
http://www.mayoclinic.org/news2005-rst/2800.html
http://www.safety.vanderbilt.edu/pdf/laser_exposure_limits.pdf
Posted by Christina Folz, OPN Managing Editor
This week’s issue of Nature highlights the newest adaptation of the optical frequency comb: an “astro-comb” that astronomers can use to scour the skies for other Earth-like planets. Current methods for detecting planets orbiting distant stars are only capable of finding large planets that have at least five times the mass of the Earth, according to a press release from the Harvard-Smithsonian Center for Astrophysics (CfA).
In order to detect a planet, astronomers typically gauge its effect on the star around which it is orbiting. Using spectrography, they measure how much the star “wobbles”—a phenomenon that is caused by the gravitational pull of the planet on the star; it is a function of the planet’s mass as well as its distance from the star. Because large planets cause the most “wobble,” they are the easiest to find. In addition, planets with tight orbits around their star are easier to detect than those with wide trajectories.
The new astro-comb, which was tested by Chih-Hao Li and his colleagues from the CfA, uses ultrashort, femtosecond pulses of laser light, linked to an atomic clock, to provide an ultra-precise standard against which light from a star can be measured. The adaptation of the optical frequency comb technique is expected to increase the resolution of the current tools by about 100 times, allowing for the detection of smaller planetary masses. According to the press release, a prototype astro-comb will be tested this summer at CfA’s Mount Hopkins Observatory in Arizona, and may be ready to use for a project in the Canary Islands by 2010.
Optical frequency combs revolutionized high-precision optical metrology by enabling scientists to accurately measure much higher frequencies of light than was ever before possible with a single tool. It is this advance for which OSA Honorary Member John L. Hall shared the 2005 Nobel Prize in Physics (with Theodor Hänsch and Roy Glauber). Hall describes his work—and its myriad exciting applications—in this month’s Scientific American magazine.