Laser

• The word laser is an acronym for Light Amplification by Stimulated Emission of Radiation.
• A laser is an intense, highly coherent, directional and monochromatic beam of light, either visible or invisible.

Applications of Laser

• Lasers are commonly used in domestic, commercial, industrial and medical applications, for example, entertainment shows, concerts, cutting, welding and surgeries. Examples of laser products include laser printers, compact disc players, barcode scanners, laser pointers and military products.

Classification

According to the International Electrotechnical Commission (IEC) standard, laser products are classified as follows:

• Class 1 laser products
  • safe under reasonably foreseeable conditions of operation, including the use of optical instruments for intrabeam viewing
  • examples: laser printers and compact disc players
   
• Class 1M laser products
  • safe under reasonably foreseeable conditions of operation, but may be hazardous if the user employs optics within the beam
  • examples: fibre-optic communication systems
   
• Class 2 laser products
  • emitting visible laser beams
  • not inherently safe for eyes, but protection by natural aversion responses, such as blink reflex, is usually adequate
  • example: amusement laser guns, laser pointers and barcode scanners
   
• Class 2M laser products
  • emitting visible laser beams
  • eye protection normally by aversion responses including blink reflex, but may be more hazardous if the user employs optics within the beam
  • example: level and orientation instruments for civil engineering applications
   
• Class 3R laser products
  • direct intrabeam viewing is potentially hazardous but the risk is lower than Class 3B lasers
  • fewer manufacturing requirements and control measures for the user than for Class 3B lasers
  • example: laser pointers and alignment lasers
   
• Class 3B laser products
  • direct intrabeam viewing may be hazardous but under certain conditions they may be safely viewed via a diffuse reflector
  • output power of continuous wave not exceeding 0.5W
  • examples: lasers for physiotherapy treatments
   
• Class 4 laser products
  • high power output devices
  • output power of continuous wave exceeding 0.5W
  • capable of producing hazardous reflections
  • may cause eye and skin injuries
  • could constitute a fire hazard
  • requires extreme caution in using
  • examples: laser projection displays, laser surgery devices and laser metal cutting devices
   

Product Label

• Each laser product should carry appropriate label(s) to international / national standards. Different styles and requirements of labels may be applied for different standards.

  The labelling requirements of IEC standard are extracted below for illustrative purpose:

  Class 1	Explanatory Label showing the class of the product
  Class 1M	Explanatory Label showing the class of the product, safety instruction, maximum output of laser radiation, pulse duration (if appropriate), emitted wavelength(s), name and publication date of standard
  Classes 2, 2M, 3R, 3B & 4	Explanatory Label showing the class of the product, safety instruction, maximum output of laser radiation, pulse duration (if appropriate), emitted wavelength(s), name and publication date of standard Warning Label

  
  Explanatory Label (sample)

  
  Warning Label (sample)

Safety Guidelines

• For Classes 1, 1M, 2, 2M, 3R, 3B & 4 laser products
  • Never view directly into a laser beam.
  • Never aim a laser beam at a person's eyes.
  • Ensure that proper explanatory and warning labels are affixed to the laser products. If the size or design of the product makes labelling impractical, the label should be included with the user information or on the package.
• Additional precautions for Classes 3R, 3B & 4 laser products
  • Follow the guidelines listed in the operation manuals of laser products.
  • Employ qualified or trained personnel for the maintenance or repair of laser products.
  • Wear suitable protective goggles and clothing when operating or servicing medium or high power laser products.
  • Post proper warning notices at areas where exposure to medium or high power laser is likely.
  • Train staff on the safe use of laser products.

Enquiries

For more information on laser safety, please contact the Electrical and Mechanical Services Department.

3 Kai Shing Street, Kowloon, Hong Kong

1823

2870 0074 or 2818 4421

info@emsd.gov.hk

Note*: This is not a legal document and is prepared for general information only.