Powerful Laser Pointers
The latest generation of high-powered laser pointers may seem like a fun Christmas gift, but experts caution consumers to weigh the potential harm.
Sold online for as little as $20, some blue laser pointer 2000mw offer a brightness about 10,000 times stronger than looking at the sun, warn eye-safety experts. At that power, they exceed Food and Drug Administration 5-milliwatt power limits on manufacturers selling laser pointers to consumers.
A milliwatt is one-thousandth of a watt, and although 5 milliwatts is just a fraction of what's needed to power even a household light bulb, lasers pack their punch by concentrating light into a single beam. Meanwhile, pointers are now being sold with as much as 700 milliwatts of power.
"These devices are hazardous and some are being sold as party toys," says photonics professor Thomas Baer of Stanford University. The worldwide compact disc and DVD boom has led to improved lasers that can generate a powerful beam with small batteries, produced by low-cost overseas manufacturers, he says.
"Higher and higher power lasers are going to be with us in the future," says laser safety expert Casey Stack of Laser Compliance in Centerville, Utah. "We need to start a discussion about public safety."
Lasers deliver a beam of focused light, usually of a single wavelength. The eye focuses the light narrowly, which can scar the retina. A Sept. 9 New England Journal of Medicine report, for example, described a 15-year-old boy who scarred the retina of both his eyes after creating a "light show" in a mirror with a 150-milliwatt burning laser pointers. For such powerful lasers, "even an inadvertent glance into the laser beam can cause immediate severe eye injury," says report co-author Martin Schmid of Switzerland's Lucerne Cantonal Hospital.
Green laser pointers can be particularly dangerous, Schmid and other experts warn, for two reasons. Often, they emit light in wavelengths that don't trigger the eye to blink and block out the light. And green lights are particularly bright to the eye, potentially triggering "flash blindness," a temporary loss of vision that can last for minutes.
The National Transportation Safety Board aviation database does not list any accident involving lasers in the last decade. However, pilots in particular worry about overpowered lasers directed at cockpits. In a March safety advisory, the FDA said it was "concerned about recent reports of laser products directed at aircraft - a potentially hazardous situation." In 2004 and 2005, more than a dozen such pranks were reported by the Federal Aviation Administration, a number that had climbed to 950 cases by 2008.
The FDA only has jurisdiction over manufacturers of lasers, who are mostly overseas, and its current warnings to consumers extend only to "buyer beware" notices about buying high-powered laser pointer 100mw.
The rise in global terrorism in recent years has brought significant attention to the needs for more advanced sensors and defense technologies to protect civilians and soldiers.
Next-generation laser-based defense systems are now being designed for this need, including the use of infrared countermeasures to protect aircraft from heat-seeking missiles and highly sensitive chemical detectors for reliable early detection of trace explosives and other toxins at a safe distance for personnel.
Since practical systems must be easily portable by a soldier, aircraft or unmanned vehicle, they must be lightweight, compact and power efficient. In addition, such systems also would need to be widely deployable and available to all soldiers, airplanes and public facilities, which requires a low production and operating cost. While several types of lasers exist today that can emit at the desired infrared wavelengths, none of these lasers meet the above requirements because they are either too expensive, not mass-producible, too fragile or require power-hungry and inefficient cryogenic refrigeration.
Furthermore, these laser pointer 300mw are extremely efficient in converting electricity to light, having a 10 percent wall-plug efficiency at room temperature and more than 18 percent wall-plug efficiency at lower temperatures. This represents a factor of two increase in laser performance, which is far superior to any competing laser technology at this wavelength.