Laser Goggles Should be inspected by ANSI

Approved ANSI laser goggles may prevent laser-caused eye risks.

Recognized Benefits

Laser beams may be harmful to the eyes, so to prevent any damage, people use laser goggles to shield laser-type light. ANSI requires annual inspections of all goggles subject to Hazard Class 3B and 4 laser systems to ensure there are no cracks, scratches or loose-fitting filters.

Protection Not Guaranteed

Though ANSI requires annual inspections of laser goggles, as mentioned in the ANSI Z136 Series of Laser Safety Standards, such goggles does not guarantee 100 percent eye protection. Wearing the proper type of laser goggles for the type of laser offers the eyes some guarantee of protection from laser energy, according to Osama Bader, MD and Harvey Lui, MD from UBC Dermatology.

Bottom Line

Laser goggles must be ANSI-approved. As the University of Utah has pointed out, the goggles must also have a label listing the optical densities and wavelengths for which protection is afforded. Before wearing the laser goggles, have ANSI annually inspect it to ensure it is in good condition, thus preventing any laser-caused eye risks.

Eye Damage from a Laser Pointer

By Carlos Mano, eHow Contributor

Laser pointers are handy, convenient and fun. They can really make an impression--especially during a high tech presentation. Many people wonder if they are safe--especially if pointed directly into the eye.

Lasers
Ordinary daylight is composed of a chaotic jumble of different wavelengths of light--different colors going in different directions. Laser light is beams of light all exactly the same color, wavelength, and direction, which produces a remarkably bright light from an extremely small beam.

ColorThe first laser pointers were red, and the cheapest ones still are. The brightest lights for the energy are the green lasers because humans see better in the middle of the light spectrum. Blue lasers have only recently become available.

UsesBesides pointers, lasers have a million uses. They are used to line up fence posts, to hang pictures in galleries, to aim telescopes and to indicate where the bullet is going to go when lasers are attached to rifles.

Eye DamageThe eye damage caused by a laser pointer is a function of how strong the laser is and how long it is shown into the eye. According to Douglas A. Johnson, a senior health physicist and laser safety officer for Texas A&M University, a brief exposure to legal lasers is harmless. Prolonged exposure more than 10 second) of even the weakest laser could be harmful.

Sporting EventsLasers have been used by spectators in sporting events to confuse players on rival teams. In some countries, the use of laser pointers has been banned at sporting events.

Lasers and the LawIn the United States, all laser pointers must be registered with the FDA, and it is illegal to sell or promote a laser pointer with more 5 milliwatts of power. In Utah it is a crime to point a laser pointer at a policeman or at a moving vehicle. In 2009 in California a woman was sentenced to 2.5 years in prison for shining a hand-held laser into the eyes of pilots landing jets at an airport. The regulations that describe the dangers of lasers to the eyes in the US are ANSI Z136. These regulations, along with International regulations IEC 60825, not only describe the dangers of different types of lasers to the eye, they offer safety suggestions such as goggle use.

What is Wavelength?

Wavelength is the distance between repeating units of a propagating wave of a given frequency. What makes a laser unique is that usually has very specific wavelength(s) that it operates at in the Electromagnetic Radiation spectrum. Electromagnetic radiation is classified into types according to the frequency of the wave.

These types include radio waves, microwaves, terahertz radiation, infrared radiation (IR), visible light, ultraviolet radiation (UV), X-rays and gamma rays. Radio waves have the longest wavelengths and Gamma rays have the shortest.

A small window of frequencies, called visible spectrum or light, is sensed by the eye of various organisms, with variations on the limits of this narrow spectrum. Many lasers operate outside the visible spectrum but still require protection... what you can't see will hurt you.

Different wavelengths require specific protection at a particular level. Lasers may also operate at different wavelengths and require different levels of protection at each wavelength. I.e. doubled Nd:YAG laser my operate at both 532 nm and 1064 nm with a required OD of 5 for both wavelengths.

If you laser glasses don't provide protection at both wavelengths you will need two different pair of eyewear. The color of the lens in laser safety glasses or goggles does not determine the wavelengths that it offers protection from.

Most laser glasses offer specific wavelength protection to provide the best visible light transmition. Do not assume that laser glasses offer protection from all lasers!

Selecting Appropriate Goggles

• Determine wavelength(s) of laser output. 

• Determine required optical density. To determine the maximum incident beam irradiance, consider the following:

       -  If the emergent beam is not focused down to a smaller spot and is greater than 7 mm in diameter, the emergent beam radiant exposure/irradiance may be considered the maximum intensity that could reach the unprotected human eye.

       -  If the emergent beam is focused after emerging from the laser system or if the emergent beam diameter is less than 7 mm in diameter, assume that all of the beam energy/power could enter the eye. In this case, use the columns labeled "Maximum Laser Output Power / Energy" in attachment 1.

       -  If the observer is in a fixed position and cannot receive the maximum output radiant exposure/irradiance, then a measured value may be used (e.g., downrange from the laser beam).

• Testing Laser Goggles

       Goggles should be checked periodically for integrity. The measurement of goggles filter optical densities in excess of 3 or 4 without destruction of the filter is very difficult. Because of this problem, requirements originally proposed by many laser hazard control guidelines stated that the optical density of goggles be periodically checked have been deleted. The greatest concern has been with goggles having specified optical densities at or only slightly above the density required for protection.

• Identification of Goggles

       All laser goggles must be clearly labeled with the optical density value and wavelength to indicate the level of protection provided. Color-coding or other distinctive identification of goggles is recommended for multi-laser systems.