What is a laser?

Radiation-Emitting Products

What is a laser?

Laser stands for Light Amplification by the Stimulated Emission of Radiation. One basic type of laser consists of a sealed tube, containing a pair of mirrors, and a laser medium that is excited by some form of energy to produce visible light, or invisible ultraviolet or infrared radiation.

There are many different types of lasers and each uses a different type of laser medium. Common laser media include gases such as argon or a helium and neon mixture, solid crystals such as ruby, and liquid dyes or chemicals. When energy is applied to the laser medium, it becomes excited and releases energy as particles of light (photons).

A pair of mirrors at either end of the sealed tube either reflects or transmits the light (see illustration below) in the form of a concentrated stream called a laser beam. Each laser medium produces a beam of a unique wavelength and color.

Laser

What are lasers used for?

Lasers are used for a variety of purposes including pointing out objects during a presentation, aligning materials at construction sites and in the home, and by doctors for cosmetic and surgical procedures. Many items you encounter on a daily basis use lasers, including CD and DVD players; bar code scanners; dental drills; laser-guided tools, such as levels; and laser pointers.

Why are lasers uniquely hazardous?

Two characteristics of laser light contribute to the hazard:

• Laser light can be emitted in a tight beam that does not grow in size at a distance from the laser. This means that the same degree of hazard can be present both close to and far from the laser.
• The eye can focus a laser beam to a very small, intense spot on its retina, which can result in a burn or blind spot.

What do you mean by laser “radiation?” Does it go through the body or cause cancer?

Some lasers emit radiation in the form of light. Others emit radiation that is invisible to the eye, such as ultraviolet or infrared radiation. In general, laser radiation is not in itself harmful, and behaves much like ordinary light in its interaction with the body. Laser radiation should not be confused with radio waves, microwaves, or the ionizing x-rays or radiation from radioactive substances such as radium.

Are all lasers legal for consumer use?

No. Some lasers are strictly for use by medical, industrial, or entertainment professionals and should only be used by a person with appropriate training and licenses.

The FDA requires labels on most laser products that contain a warning about the laser radiation and other hazards, and a statement certifying that the laser complies with FDA safety regulations. The label must also state the power output and the hazard class of the product. Consumer laser products are generally in classes I, II, and IIIa, while lasers for professional use may be in classes IIIb and IV.

What do the different classifications of lasers mean?

Laser Hazard Classes

The Food and Drug Administration (FDA) recognizes four major hazard classes (I to IV) of lasers, including three subclasses (IIa, IIIa, and IIIb). The higher the class, the more powerful the laser and the potential to pose serious danger if used improperly. The labeling for Classes II–IV must include a warning symbol that states the class and the output power of the product. Approximate IEC equivalent classes are included for products labeled under the classification system of the International Electrotechnical Commission.

Class FDA	Class IEC	Laser Product Hazard	Product Examples
I	1, 1M	Considered non-hazardous. Hazard increases if viewed with optical aids, including magnifiers, binoculars, or telescopes.	laser printers CD players DVD players
IIa, II	2, 2M	Hazard increases when viewed directly for long periods of time. Hazard increases if viewed with optical aids.	bar code scanners
IIIa	3R	Depending on power and beam area, can be momentarily hazardous when directly viewed or when staring directly at the beam with an unaided eye. Risk of injury increases when viewed with optical aids.	laser pointers
IIIb	3B	Immediate skin hazard from direct beam and immediate eye hazard when viewed directly.	laser light show projectors industrial lasers research lasers
IV	4	Immediate skin hazard and eye hazard from exposure to either the direct or reflected beam; may also present a fire hazard.	laser light show projectors industrial lasers research lasers lasers used to perform LASIK eye surgery

What are laser pointers?

Laser pointers are tools used for pointing out objects or locations, and are defined as "surveying, leveling, and alignment laser products" in an FDA regulation. They are commonly used during lectures and astronomy presentations, and laser pointers incorporated into spirit levels and hand tools are also very popular. In recent years laser pointers have become readily available, and are commonly sold in hardware, pet, hobby, and office supply stores.

Are laser pointers safe?

When used properly lasers pointers pose minimal risk if they meet laser power limits. Laser pointers are misused when they are directed at the eyes or treated as toys. The light energy from a laser pointer aimed into the eye can be more damaging than looking directly into the sun. In addition, the startling effect of a bright beam of light aimed at someone driving a car or operating other machinery can cause serious accidents.

The FDA is concerned about the increased availability of a variety of laser products that may be used unsafely. Green, blue and violet laser pointers have the agency particularly concerned. While there are legitimate uses for these laser pointers, they may be altered to become more powerful and unsafe if not used responsibly.

Is the brightness of the laser light a good indicator of its power and eye hazard?

No. Never assume the color brightness of a laser beam indicates its power.  In lighted conditions (indoors or outdoors), a beam from a powerful laser can appear to be the same brightness or dimmer than the beam of a less powerful laser. For example in the photo below, the green laser beam appears much brighter than the red and far brighter than the blue.  These are actually equally powered lasers and all three present the same eye hazard from looking into the beam. If you see a bright blue or violet laser beam with brightness similar to a green laser, you can safely assume that the blue/violet laser light is far more powerful and looking directly into the beam will cause severe and immediate eye damage.

As a rule, you should never look directly into any laser beam.

What is the proper use of a laser pointer?

Remember, laser pointers are not toys and they should only be used by an adult, or with adult supervision.

• Never aim or shine a laser pointer at anyone.
• Only activate the laser pointer when you are using it to point at a nearby object.
• Do not buy laser pointers for your children. Lasers are not toys.
• Before purchasing a laser pointer, make sure it has the following information on the label:
  • a statement that it complies with Chapter 21 CFR (the Code of Federal Regulations)
  • the manufacturer or distributor's name and the date of manufacture
  • a warning to avoid exposure to laser radiation
  • the class designation, ranging from Class I to IIIa. Class IIIb and IV products should be used only by individuals with proper training and in applications where there is a legitimate need for these high-powered products.