Laser Safety : Part 2

by Food and Drug Administration (FDA)

(Page 2 of 2)

Industry and the Military

Factories use powerful lasers to manufacture a wide range of products. Lasers can drill or weld metal, cut holes in the tips of baby bottles, or solder tiny circuits for electronics parts.

They can strip wires, etch trademarks, drill tiny holes for watch jewels, and cut out cloth for dozens of suits at once.

Although armies don't vaporize their enemies with lasers like they do in science fiction movies, the military has found lots of other uses for lasers.

Lasers guided the "smart bombs" used during the Persian Gulf War, for example. Lasers transmit communications on the battlefield, and in training, the Army uses laser "guns" to simulate the firing of real ammunition.

Arts and Entertainment

Dazzling laser light shows are standard features at many amusement parks, rock concerts, and planetarium shows, and they are monitored for safety by FDA inspectors (see accompanying article). Programmed to move to the music, the laser beams dance and flash across a suspended screen, the night clouds, and, under careful safety precautions, even the audience.

And in photography and art, lasers can produce three-dimensional photographs called holograms. You may have seen them on your credit cards — banks use holographic emblems to protect against counterfeiting. Scientists say someday holograms will give us three-dimensional pictures of everything from molecules to city streets. Perhaps we'll even watch three-dimensional television on table tops.

Measuring Up

Because of their precision, lasers have offered a new way of taking measurements.

With lasers, scientists can calculate the distance to the moon more accurately than ever before. In 1969, astronauts placed an object on the lunar surface that can reflect a laser beam back to its precise origin on Earth. Using a 4-billion-watt pulse laser, scientists now measure the distance to the moon to within 6 centimeters, or 2.4 inches.

Lasers can also take small measurements, such as the vibration of atoms and molecules, the frequency of light, and the amount of trace pollutants in air and water.

Lasers for the Future

Lasers have the potential to generate clean, powerful energy from the world's most abundant natural resource — sea water — using the same process that fuels the sun and stars. Called fusion, the process involves compressing atoms together to release energy.

Fusion on the sun is produced by tremendous gravity forcing atoms together. On Earth, scientists can briefly produce fusion with lasers. At the Lawrence Livermore National Laboratory in Livermore, Calif., scientists have developed a powerful laser called NOVA. In a fraction of a second, this laser can heat a tiny pellet of frozen hydrogen several million degrees. The heating is so fast that the atoms don't have a chance to escape as vapor. Instead, they compress and implode. For a brief instant, fusion results. A mini-star is born.

So far, however, the laser is not powerful enough to produce sustained fusion, and the technology is still decades away.

Scientists already know how to split an atom to produce energy. Called fission, the reaction is used in nuclear power plants and atomic bombs. Unlike fission, laser-generated fusion would produce few hazardous wastes — some scientists say none at all.

As the laser industry grows, scientists continue to discover new applications for this special light. Some speculate the next generation of scientists will use lasers to explore other star systems or fuel spaceships far into the galaxy.

For now, however, the future scientists in Donaldson's optics class have fun with laser basics.

"Lasers are the most 'sexy' thing, I guess you could say, that we do," says the science teacher. "They're beautiful scientifically because the work is so clean and clear and measurable. Plus, it's just fun to do.

"I appreciate the scientific part of it," Donaldson adds. "The kids appreciate the fun part."

How FDA Monitors Laser Safety

FDA regulates all kinds of lasers, from the ones used in surgery to those found in supermarket checkout scanners. The agency has authority to regulate them under the Radiation Control for Health and Safety Act and the Medical Device Amendments to the federal Food, Drug, and Cosmetic Act.

In monitoring laser safety, FDA recognizes four major classes and two subclasses of lasers, ranging from those that pose no known hazard to those that pose serious danger if used improperly. The higher the class, the more powerful the laser. Depending on the strength of the laser, FDA requires a variety of safety features such as safety locks, emission indicators, and switches that automatically turn off the laser in certain circumstances.

FDA requires that most lasers bear warning labels about radiation and other hazards, and all must display a certification label stating that the laser complies with FDA safety regulations.

FDA inspectors check 220 of the approximately 1,000 laser manufacturers in the United States each year, according to Jerome Dennis of the division of standards enforcement in FDA's Center for Devices and Radiological Health. FDA repeatedly inspects plants that have frequent violations. The center has a laser laboratory in Rockville, Md., to provide technical support to the inspectors in the field.

FDA also performs 110 tests on lasers in use each year, such as ones operating in factories and supermarkets. Producers of laser light shows, for example, are required to tell FDA where they are planning a display, so that the agency can inspect it if possible. "We do try to pop in on them unannounced and unexpected," says Dennis.

The Center for Devices and Radiological Health keeps track of laser injuries through several voluntary reporting programs. There have been serious eye injuries, skin burns, and electrocutions reported to FDA over the years. Most of the injuries, however, were the result of human error and misuse, according to Richard Felten, a regulatory review scientist at the center. Either the laser users didn't wear protective eyewear, or they wore the wrong kind for that particular laser, or they didn't heed the warning labels on the device.

Eye protection is not a foolproof defense against laser injury and should only be used as a backup to other safety measures, Dennis advises. No one should look directly into a laser beam even while wearing a pair of goggles.

"From the information we have, it appears that many reported eye injuries and skin burns occur because people are doing something incorrect," says Felten. "However, when the user follows the recommended safety procedures, lasers can be used in a safe manner."

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.