Blinding Insights into Laser Pointers and Planes

23. April 2008

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

 

2008-04 April, Lasers ,

Comments

6/13/2008 11:45:32 PM #
It's official. Yesterday (on June 11, 2008), the Australian Capital Territory government announced that it will ban high-powered laser pointers under the Prohibited Weapons Act of 1996. For more information, visit: www.photonics.com/.../91984.aspx.