Laser Safety

Overview

The laser safety program is established to facilitate and ensure the safe and knowledgeable use of lasers in laboratories, classrooms, and the environment.  The laser safety program is administered by Environmental Health and Safety to ensure the safe use of lasers and compliance with requirements of State, American National Standards Institute (ANSI) and other related regulations and standards.  The program applies to all university personnel owning, supervising, operating, and working in the proximity to Class 3B or Class 4 lasers.

Classes of lasers

Lasers are classified to describe the capabilities of a laser system to produce injury to personnel. This classification rates from Class 1 lasers like laser printers to Class 4 lasers like 2000 Watt carbon dioxide laser used to cut steel. Manufacturers are required to label a piece of equipment with the appropriate warning label and classification for Class 2, 3 and 4 lasers. 

Class Description Hazards Examples

Class 1

Lasers that are considered to be incapable of producing damaging radiation levels and are thereby exempt from control measures.

No hazard

CD Rom players

Class 2

Visible wavelength laser systems with some possibility of injury if stared at although the output of the laser is not intended to be viewed.

Low hazard

An example of a Class 2a laser is a grocery store point-of-sale scanner.

 

Class 3R

Laser systems in which intrabeam viewing of the direct beam or specular reflections of the beam may be hazardous.

Moderate hazard

Most laser pointers are 3R lasers.

 

Class 3B

Intermediate power devices where direct viewing is always hazardous. 

Moderate to high hazard

Some examples of Class 3B lasers uses are spectrometry, stereolightography, and entertainment light shows. 

Class 4

Laser systems whose direct or diffusely reflected radiation may be hazardous and where the beam may constitute a fire hazard. Class IV systems require the use of controls that prevent exposure of the eye and skin to specular or diffuse reflections of the beam.

High hazard

Some examples of Class 4 laser use are surgery, research, drilling, cutting, welding, and micromachining. 

 

 

Hazards

The primary concern in laser safety is the possibility of eye injury. A secondary hazard is damage to the skin. Biological effects of laser light may depend on a number of factors including the wavelength of the light, its power, whether it possesses a continuous wave nature or is pulsed, or whether it is the result of a direct exposure of laser light rather than a diffuse reflection. Lasers are to be treated with great respect and caution.

Beam Hazards

  • Potential injury to the eye
  • Potential injury to the skin

Non-beam Hazards

  • Electrocution
  • Fire
  • Exposure to air contaminants, hazardous gases, laser dyes and solvents

Protective practices

Substituting a less powerful laser, especially during alignment, is one of the most effect ways to prevent accidents. The higher the power of the laser, the more it will be necessary to have controls.

The second most effective method for accident prevention is to employ engineering controls, such as lasers system enclosures, interlocks, and beam stops. Enclosures can be as simple as providing PVC tubing along the beam path, encompassing most of the laser light.

Eyewear in particular is a very effective control, if and only if, it has the correct optical density (OD), and is actually worn. This is a control that is easily defeated, however, such as when a laser operator decides to push his/her goggles up on the forehead to “get a better view.”

Protective eyewear is required for all individuals who are exposed to Class 3B and Class 4 laser radiation. The eyewear must be labeled with the wavelength to be attenuated and the optical density (OD) for each wavelength. All eyewear should be inspected every six months to ensure that there is no damage, such as cracks, scratches, holes, or discoloration. All eyewear should fit the user well.

When selecting eyewear the following should be considered:

  • Laser wavelength or range
  • Optical Density (OD) for that wavelength or range
  • Damage Threshold of the eyewear (the maximum irradiance or beam power that the eyewear will protect against for at least 5 seconds)
  • Visual transmittance of the eyewear (how much visible light is transmitted to the eye)
  • Field of view and curvature of the lens
  • Goggles large enough to accommodate prescription eyewear
  • Ventilation to prevent fogging and general comfort
  • Effect on color vision
  • Impact resistance and cost