Class 1 Lasers and Laser Systems
A Class I laser is considered incapable of producing damaging radiation levels during operation or maintenance and is, therefore, exempt from control measures or other surveillance requirements.
Examples of Class 1 Lasers include:
- lasers in the visual spectrum which produce no more than 0.4 microwatts of power
- a laser which contains a more powerful laser within an enclosure which is inaccessible during operation. Since lasers are not classified based on beam access during service, most Class 1 industrial lasers will consist of a higher powered (higher classed) laser enclosed in a protective enclosure that features proper interlocks and labels. The enclosure could be a room (walk-in protective housing) which requires a means to prevent operation when the room is occupied.
- Class 2 lasers must be visible.
- The output power of these lasers must be low enough that a person’s natural aversion to bright light will protect the eye.
- These lasers must produce less than 1 milliwatt of visible, continuous wave (CW) light.
- Looking directly into the beam of one of these lasers is relatively safe if the person does not force himself to ignore the natural aversion response. Normal aversion response is generally considered to take 0.25 seconds.
- These lasers are allowed to produce more power than Class 1 limits only for limited time periods (less than 1000 seconds).
- A Class 2a laser must be designed so that intentional viewing of the beam is not anticipated.
- A supermarket bar-code scanner is a typical example of a Class 2a laser.
Class 3 lasers are divided into two subgroups (Class 3a and Class 3b) so there is no plain Class 3.
- Class 3a lasers are allowed to exceed the power limit of Class 2 by no more than a factor of 5. Therefore a CW, visible Class 3a laser has a maximum power of 5 mW.
- Often these lasers will have an expanded beam diameter so that no more than 1 mW can enter a fully dilated pupil which is 7 mm.
- Class 3b may be either visible or invisible.
- They cannot produce more than 500 mW of CW power. This is enough power to result in an injury before a person could react.
- Both the eye or the skin can be injured by exposure to direct beam or mirror reflection. Scattered energy (diffuse reflections) is not considered hazardous in most situations, unless the device is operating near its upper power limit and the diffuse target is viewed at close range.
- Class 4 lasers present the very greatest hazard potential.
- Both the eye and the skin may be readily injured by either direct beam, mirror reflections, or diffuse reflections.
- Class 4 laser use requires the greatest number of control measures.
- Fire hazards are also a very important concern.