Classification of Lasers

All lasers and laser system do not pose the same degree of risk. For this reason, a classification system was developed to categorize these systems depending on their potential to cause biological damage. Although a variety of classification standards exist, depending upon the area of application (ex. manufacturing vs application), the ANSI standard is a generally accepted standard.

Seven classes are used to delineate the risk of damage associated with exposure to a laser beam, and range from Class 1 (no potential damage) to Class 4 (high degree of potential damage).

1

Not known to be able to cause biological damage

Examples:
(a) A very low power laser which emits a low energy beam which is unable to cause biological damage (i.e. visible spectrum emission less than 0.4 µW)

b) A high power laser enclosed in such a fashion that direct access to the beam is not possible.Note: During maintenance or servicing, access to a high power laser beam may occur. (Only qualified individuals are authorized to conduct such activities.)

1MIncapable of producing hazardous exposure conditions during normal operation unless the beam is viewed with an optical instrument such as eye-loupe (diverging beam) or a telescope (collimated beam)
2- ocular hazard exists when chronic viewing occurs
- limited to visible lasers (either continuous wave or repetitive pulsed)
- normal aversion of the eye sufficient to prevent injury
- emit above Class 1 level but less than 1 mW radiant power
2Ashould now be treated the same as Class 1
- designation applied to lasers which are “not intended for viewing”
         i.e. supermarket laser scanner
- based upon 1000 second exposure
- upper power limit is 4.0 mW
2M- limited to visible lasers (either continuous wave or pulsed)
- potentially hazardous if viewed with certain optical aids
3Anow called Class 3R unless the beam diameter exceeds 7 mm, in which case they could be Class 1M or 2M 
- intrabeam hazard exists for ocular injury but not a serious skin hazard
- intermediate power lasers ( 1-5 mW, continuous wave)
- permitted to exceed the power limit of Class 2 by five times
- often have a expanded beam such that no greater than 1 mW enters a fully dilated pupil (7 mm)
- depending upon reference standard may include invisible and visible lasers
3R- intrabeam hazard exists for ocular injury but not a serious skin hazard
- intermediate power lasers (1-5 mW, continuous wave)
- permitted to exceed the power limit of Class 2 by five times
- often have a expanded beam such that no greater than 1 mW is enter a fully dilated pupil (7 mm)
- depending upon reference standard may include invisible and visible lasers
3B- both ocular and skin damage possible when direct exposure occurs
      (including mirror reflections)
- scattered reflection not usually considered dangerous, unless laser is operating at the upper power limit and the beam is viewed at a close distance.
- may be visible or invisible lasers but cannot produce greater than 500 mW of continuous wave power
4- ocular or skin damage possible through direct or indirect exposure
- risk of fire 
- high power lasers (greater than 500 mW continuous wave)

Back to top