Laser policy application

Information about how the University laser safety policy statement SEG GN07 applies to different departments

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The University expects ALL heads of departments to be aware of the potential sources of laser radiation and to identify those circumstances where the risks from lasers might be considered significant.

Lasers are used in many different systems, from general office environments (e.g. laser pointers, laser printers, laser projectors/displays, telecommunications) to more technical environments, such as workshops (e.g. laser alignment, precision measurement, welding, and cutting) and laboratories (e.g. research, imaging, positioning, analysis). The vast majority of these commercially available products are safe under reasonably foreseeable conditions of use. However, it is acknowledged that some products can be supplied without appropriate shielding (e.g. laser cutters, 3D printers) or are used in ways in which exposure is unsafe (e.g. laser displays directed to individuals, high powered (>1mW) laser pointers in lecture theatres). It is therefore important that careful consideration is given to all laser products to ensure they are supplied in a safe manner and are used as instructed. If there is any doubt on either of these points, then the full requirements of this policy may apply.

The term LASER is an acronym for Light Amplification by the Stimulated Emission of Radiation. As a form of non-ionising optical radiation, it is uniquely coherent (all the waves are in phase), monochromatic (i.e. single wavelength or very narrow bandwidth) and highly collimated (i.e. low angle of divergence). It is these properties that pose a specific risk of injury to the eye and skin, which is dependent upon the wavelength and output power. 

The Control of Artificial Optical Radiation at Work Regulations 2010 place a legal obligation on the University to eliminate the risk of adverse health effects from lasers or, if that is not reasonably practicable, to reduce the risk to as low as is reasonably practicable. Although this legislation only covers employees, not students or visitors, the University will apply the same principles of control for anyone across the University who might be exposed to a laser hazard.

In order to eliminate a risk of adverse health effects from lasers, any exposure to the laser beam itself must be within prescribed safe limits for both eye and skin exposure. These so-called Exposure Limit Values are set out in Annex II of the European Directive 2006/25/EC and are reiterated in British Standards as Maximum Permissible Exposure (MPE) limits. 

Lasers are classified according to their potential to exceed the MPE. In general, lasers that are classed as Class 1, 1M, 1C, 2 and 2M (Table 1) can be considered reasonably safe under normal conditions. When new laser products are brought into a department, the person bringing in the laser should identify the laser classification for the product. Provided the laser product is Class 1, 1M, 1C, 2 or 2M and used as prescribed in the instruction or product manual, then no further action is required. 

Lasers that are classed as Class 3R, 3B or 4 may exceed the MPE levels and as such, the risks from these lasers would be considered significant and all standards in this policy statement will apply.

If there is any uncertainty, then a departmental laser supervisor should be notified or the University Laser Safety Officer consulted.

Table 1:  Descriptions of Class 1, 1B, 1C, 2, and 2B lasers

Class 1

Laser products, which are safe under reasonably foreseeable conditions of operation, either because of the low emission of the laser itself, or because of its engineering design such that it is totally enclosed and human access to higher levels is not possible under normal operation. 

Note:  If access panels of a totally enclosed system are removed for servicing etc. then the laser product is no longer Class 1 and the precautions applicable to the embedded laser must be applied until the panels are replaced.  It is important that when such systems are installed in open areas, the potential for this should be considered prior to first installing the system.

Class 1M

Laser products emitting in the wavelength range 302.5 nm to 4000 nm, whose total output is in excess of that normally permitted in Class 1 laser products but because of their very low power density, large beam diameter, or high divergence does not pose a hazard in normal use.  However, they may be hazardous to the eyes under certain conditions if gathering optics (e.g. binocular, telescope, and microscope lens) are used with them.

Class 1C

Any laser product which is designed explicitly for contact application to the skin or tissue, but the ocular hazard is prevented by engineering means (i.e. it must be in contact with the skin before, and only, when the laser is emitted) and through following the instructions provided with the product.

Class 2

Lasers that only emit visible radiation (i.e. 400 nm to 700nm) and whose output is such that they are safe for accidental viewing because a person’s natural aversion response (i.e. blink reflex, moving head) provides adequate protection under reasonably foreseeable conditions.

Class 2M

Lasers that only emit visible radiation (i.e. 400 nm to 700nm) and whose total output is in excess of that normally permitted in Class 2 laser products but because of their very low power density, beam diameter, or high divergence does not pose a hazard for accidental viewing.

Some laser pointers are now available with quoted output powers of up to, and even exceeding, 50 mW, thus placing them in the higher class of lasers. These pose a significant risk of injury, particularly as the likelihood of exposure from either direct or specular reflections (i.e. Class 3B or 4) is reasonably foreseeable when pointers are used for lectures and presentations.

In addition, the classification of laser pointers from certain suppliers has been shown to be inadequate. This is particularly concerning with the introduction of green laser pointers. The eye is more sensitive to green light and so, although the power output may be similar, a green laser will appear brighter than, for example, a red laser. In addition, the green light is generated by ‘frequency doubling’ a 1064nm near-infrared laser, meaning Class 2 green laser pointers of this type should include a filter to block any near-infrared emission. If not, or the power output exceeds the maximum permissible exposure limit, then the risk of eye injury is likely to be significant. Even a true Class 2 green laser pointer can be problematic, as individuals may experience some form of ‘after image’ when the beam is displayed on a projection screen, particularly when viewed from close-by.

Individuals must ensure that laser pointers are obtained from reputable suppliers and that they are correctly classified. Lasers marked Class 3R or above, or where the known output power is greater than 1 mW, or whenever there is any uncertainty, must not be used as laser pointers without first obtaining written approval from the relevant departmental laser supervisor or University Laser Safety Officer.

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