Lasers are classified on the basis of their accessible emission to give the user a simple guide to beam hazard. It is the manufacturer’s responsibility to classify the laser, but a user who significantly modifies a laser takes on the role of manufacturer including the responsibility to reclassify (or confirm the original classification). Where original equipment manufacturer (OEM) lasers are purchased for integration into a laser system, it will be the integrators responsibility to classify the final product. Where laser products are purchased from outside the European Union, the purchaser will become an importer and may have responsibilities for classification and ‘CE’ marking.

For each laser class there are accessible emission limits (AEL), generally expressed in Watts or Joules measured through one or more specified apertures placed at a specified positions. The accessible emission limits are related to the maximum permissible exposures such that the laser class gives an indication of the beam hazard. Full details of assessment procedures are given in BS EN 60825-1:2014. It should be noted that it is often possible to classify a laser product without making any measurements. Should it be necessary to make measurements in order to classify a product then further guidance is available in PD IEC/TR 60825 13:2006 Safety of laser products – Part 13: Measurements for classification of laser products.

A3.1 Class 1

Class 1 laser products are safe in normal use under reasonably foreseeable conditions. There are two types of class 1 laser products:

A3.1.1 Inherently class 1 or exempt

The laser output is safe because the output of the laser source is too low to cause harm, even if magnifiers or other such optical devices are used to modify the laser beam or assist viewing. Such devices may be either assigned to class 1, or referred to as an exempt laser product. This code places no requirements on the use of inherent class 1 / exempt lasers.

A3.1.2 Class 1 laser products containing an embedded laser of higher class

A class 1 laser product containing an embedded laser of higher class are safe because of engineering design. In general, this means that the laser radiation is totally enclosed, preventing it becoming accessible to the user in normal operation.

In this Code the term ‘class 1 embedded‘ is restricted to products that are Class 1 but contain a Class 3B or Class 4 laser that is not accessible during the service operations specified by the manufacturer.

The use of class 1 (embedded) laser products in general is dealt with in this code because: (i) a degree of preventative maintenance and care may be required to preserve its safety; and (ii) the laser hazard may be exposed during servicing of the product.

However, this code places no requirements on the use of class 1 (embedded) laser products that are intended for use as consumer products, including desk top laser printers, and photocopiers, CD and DVD players and recorders provided they are serviced off site.

A3.2 Class 1M

Class 1M laser products have a total output that exceeds the accessible emission limit for class 1, but is emitted into a well-collimated beam with a diameter that exceeds the diameter of the limiting aperture for that wavelength and is outside the retinal hazard region. Hence, they are safe for ‘naked eye’ viewing (i.e. without the use of viewing aids) by virtue of the fact that the power or energy passing through the limiting aperture will be below the MPE.

The applicability of class 1M is restricted to laser wavelengths in the range 302.5 nm to 4 µm. This is deemed to be the reasonably foreseeable transmission range of optical viewing aids and corresponds approximately to the transmission window of fused quartz.

Class 1M lasers products are regarded as low risk in this code.

A3.3 Class 1C

Class 1C is applicable when the laser radiation is intended to be applied in contact with the intended target, either skin or non-ocular tissue and has safeguards that prevent leakage of laser radiation in excess of the AEL of class 1. The laser product can be assigned to class 1C only if it also complies with a set of safety requirements for class 1C laser products that can be found in an applicable IEC vertical standard.

A3.4 Class 2

Class 2 laser products emit low levels of visible radiation (i.e. in the wavelength range 400 nm to 700 nm) and are safe in normal use by virtue of the natural aversion response of the eye to bright light, which is deemed to limit the duration of exposure to 0.25 s. Nevertheless, they may present a severe dazzle hazard that must be considered in an optical radiation-specific risk assessment. For a continuous wave (CW) laser the class 2 AEL is 1 mW.

Class 2 laser products are regarded as low risk in this Code.

A3.5 Class 2M

Class 2M laser products have a total output that exceeds the accessible emission limit for class 2, but that is emitted into well-collimated beams of visible radiation (i.e. in the wavelength range 400 nm to 700 nm) of diameter greater than the pupil size of the eye (7 mm maximum); thus are safe for ‘naked eye’ viewing. That is without the use of viewing aids), by virtue of the natural aversion response of the eye to bright light, which is considered to limit exposure to 0.25 s, and the fact that the eye will only collect a fraction of the total laser output. They are safe in normal use if:

• the observer does not stare into the beam; and
• lenses and/or mirrors are not used to reduce the laser beam diameter and then re-collimate the beam; and
• Telescopic optical devices are not used to assist viewing. Control of such viewing aids and optical arrangements is generally sufficient to ensure safety.

Class 2M lasers products are regarded as low risk in this code. Nevertheless, they present a severe dazzle hazard that must be considered in an optical radiation-specific risk assessment.

A3.6 Class 3R

The emission from class 3R laser products exceeds the exposure limit value / maximum permissible exposure for an accidental exposure and must therefore be considered unsafe for direct viewing of the laser beam, whether in aided or unaided viewing. Nevertheless, the risk of injury is regarded as low due to the safety margins used in the derivations of exposure limit values and maximum permissible exposures.

The applicability of Class 3R is restricted to laser wavelengths greater than 302.5 nm, since for shorter wavelength ultraviolet the 5 times excess is deemed too great a factor for the exposure to be low risk.

Unlike class 1M and class 2M, where unaided viewing is considered safe, eye exposure to the beam from a class 3R laser carries a small risk of injury and would be a breach of the Control of Artificial Optical Radiation at Work Regulations 2010.

Class 3R lasers products are regarded as low hazard in this code.

A3.7 Class 3B

Class 3B laser products are medium power devices for which ocular exposure to either the direct beam or a specular reflection would carry a high risk of injury; ocular exposure to a diffuse reflection is normally safe, subject to certain conditions (i.e. a minimum viewing distance of 130 mm and a maximum viewing time of 10 seconds). For a CW laser in the visible or infrared wavelength range the Class 3B AEL is 500 mW.

Class 3B laser products are regarded as high hazard in this code.

A3.8 Class 4

Class 4 laser products are high power devices for which exposure to the direct beam, specular and diffuse reflections is generally hazardous. They may also cause skin burns and may present a fire hazard. There is no AEL for Class 4.

Class 4 laser products are regarded as high hazard in this code.