Lasers are more dangerous than most people understand, and your eyes are the most vulnerable to laser damage.
Too many people, accustomed to seeing lasers used as pointers, in movies and to put on exciting shows, don’t understand the danger. Used properly, lasers are useful for many applications, but everyone should learn how to protect their eyes, even from low power laser beams. People who work with powerful lasers in scientific laboratories, medical institutions or industry need to fully understand the risk and how to protect themselves.
What is Laser Light?
It’s a beam of radiation that, unlike normal light, spreads all around, is coherent. It all goes into one direction. Also, it consists of the same electromagnetic wavelength or color. And the radiation’s duration, its pulse, is uniform.
A set amount of energy creates the beam, and this varies a lot. That’s why teachers or business presenters can safely use simply laser points, but some laser beams are powerful to incinerate materials, starting fires.
The more intense the laser beam is, the more damage it causes, and the more precautions people need to take to protect their eyes.
How Lasers Damage Eyes
All laser light beams carry energy and heat. And the more concentrated and powerful the beam of light, the more heat it transmits. They are also more dangerous the shorter the pulse’s duration.
* Small, highly focused beams of light go right through your cornea and lens, which focuses the light even more, so it hits a tiny spot on your retina, destroying photoreceptor cells. This causes a temporary or permanent blind spot before you can blink.
* Powerful lasers in the visible to near infrared spectrum (400 to 1400 nanometers) heat your entire retina.
* Your cornea absorbs laser beams with a wavelength of under 300 nanometers and beams in the high infrared range, which can inflame them, called photokeratitis, or more seriously burn them.
* Your eye’s lens absorbs laser beams with a wavelength of under 400 nanometers, which increases the risk of cataracts. That clouds your lens, blocking your vision.
* A wider laser beam can cause momentary flashblindness just like any other extremely bright light when it shines directly into your eyes before your blinking reflex can work.
* The human eye cannot see infrared laser light. Therefore, such a beam can damage your eye without even triggering your blinking reflex.
* Some lasers are so powerful they damage your eyes even though after something has diffused the beams. Even in that weakened state, they cause damage.
* Some laser beams, typically closer to blue or ultra-violet on the spectrum, cause damaging photochemical reactions in the tissue of your eyes.
Lasers are Classified According to Their Danger
The American National Standards Institute issued its Z136 standards classifying lasers according to the risk they pose, and the Occupational Safety and Health Administration uses them. However, everyone should understand how to protect your eyes.
Take Precautions With All Lasers
Laser pointers are Class 1, which are generally safe. However, the classification assumes everybody uses the product as designed. Laser pointers as properly used pose no danger. However, there is a case on record of an 11-year-old girl who temporarily damaged her eyes by staring directly at a pointer’s beam.
Therefore, people should treat every laser with respect. Even with laser pointers, don’t stare at the beam or the dot.
Light Show Safety
In the United States, the Food and Drug Administration and some state agencies regulate the use of laser light shows. Those require beams with high power, and therefore do pose some risk. Entertainment venues use beamstops to terminate the beams before they can cause any damage.
The most common way of avoiding risk to the audience is to shine the beams over the heads of the audience, thus avoiding the eyes if the audience. This is the usual practice in the United States. In some countries producers scan the laser beams at the audience, but must do so fast enough to keep their exposure in a safe zone.
Airplane and Motor Vehicle Safety
It’s now against the law to shine a laser light at an airplane or motor vehicle. You could cause flashblindness in the pilot or driver, making them lose control and crash.
Laser Protection in the Workplace
* Understand the risk. Don’t become complacent.
* Everybody should know where an infrared laser beam goes.
* In a laboratory, only use an optical table. Make sure all laser beams go only horizontally. Stop all the beams at the edge of the table. People should never place their faces or eyes at the same level of the laser beam, because reflected beams could leave the table.
* Leave watches, rings and all other jewelry outside the laboratory. Everything inside it should have a matte finish to reduce specular reflections.
* Reduce power when adjusting and aligning beams.
* Use an interlock to automatically shut the laser down when needed. The most dangerous lasers, Class 3B and Class 4, normally come with an interlock system. That means they immediately shut down under dangerous circumstances. For example, if the laboratory door opens.
* Have a Certified Laser Safety Officer on duty.
* Restrict access to lasers while in use only to trained and authorized personnel.
Class 3R, 3B and 4 Lasers Require Goggles and Glasses for Safety
These are the most dangerous types of laser, and they are mainly used in laboratories, industry, hospitals and by the military. Everyone working with them should wear the proper protective eyewear.
These act as filters to absorb the laser light, greatly reducing its intensity. The manufacturers make them of glass and polycarbonate to filter specific wavelength ranges. You make certain your glasses have the correct wavelength, or they cannot filter the laser beam.
The other important aspect of laser safety glasses is Optical Density. This is basically how strong the glasses are. The stronger your laser beam, the higher OD it requires to keep your eyes safe. However, the beam’s energy is not the only variable that affects OD. The pulse’s duration affects the beam’s danger, so it also affects the OD, or whether the light is continuous instead of pulsed.
Again, you must make certain you wear the proper glasses. Manufacturers post their wavelength and OD in the frames.
Your Certified Laser Safety Officer knows the requirements for the laser you are using.
These windows are filters for particular laser wavelengths and OD just like the glasses and goggles. They are acrylic or glass, and come 3 millimeters thick. Just like the glasses and goggles, you must make certain your window is appropriate to filter the light beam of your laser.
Like other light, laser light beams end when something absorbs their energy, blocking it. Have your CLSO design and set up the work space to eliminate the laser beam after it has performed its function. These barriers come as curtains or mobile stands.
Whether you play or work with lasers, always respect them, and be careful to protect your eyes.
At Phillips Safety Products we want everyone to protect their eyes from lasers. We make the safety laser glasses and goggles, windows and barriers your workplace needs to protect the eyes and vision of your employees. Contact us today.