Professional Support in Laser Safety

Laser Safety: A Brief Guide

Lasers are devices that produce intense beams of light, or more strictly of optical radiation (since laser emission can be in the form of visible light or of invisible infrared or ultraviolet radiation). The word LASER stands for Light Amplification by the Stimulated Emission of Radiation, and describes the process by which a laser beam is generated. This process differs from the way in which optical radiation is produced by other light sources (electric lamps, for example).

Lasers are used extensively in many different areas, including measurement and sensing applications, industrial processing (such as cutting, drilling, welding and surface treatment), medical diagnosis and surgery, cosmetic applications such as skin treatment and hair removal, telecommunications using optical fibres, and laser displays and light shows.

Laser hazards

Because of the intensity of the output beam and the ability of lasers to produce very high concentrations of optical power at considerable distances, many lasers are hazardous. They can cause serious injuries to the eyes and can also burn the skin. There may be other hazards, too, either related to the laser equipment itself or arising from the effect produced by its beam. With high-power lasers there is a possibility of fire, since the beam can ignite flammable materials. Harmful fumes can be produced from laser processes involving vaporisation. Visible-beam lasers, even those of very-low power which cannot cause direct harm, may nevertheless startle and dazzle anyone who is suddenly exposed to the beam.

Laser classification

The safety of lasers is based on the proper design of laser equipment and on the adoption of appropriate precautions during use.

A laser product (which is any equipment that incorporates a laser) is allocated into one of several hazard classes, depending on its potential for causing injury. These are defined in the international standard for laser safety IEC 60825-1 (Safety of laser products – Part 1: Equipment classification & requirements). This standard applies throughout much of the world, and is adopted in Europe as EN 60825-1, where it is used to demonstrate compliance with the safety requirements of a number of European Directives.

Lasers that are safe under normal conditions of operation are Class 1. This class can, however, cover equipment that has an enclosed laser of high power whose emission is not accessible under normal conditions of use, but which may become accessible during maintenance or servicing. (Many industrial lasers fall into this category.)

The most hazardous lasers, which can be capable of causing serious injury to the eyes and the skin as well as being a fire risk, are Class 4. Intermediate classes (designated 1M, 2, 2M, 3R and 3B) represent varying degrees of risk to the eyes. The ‘M’ classes can pose an eye risk if the laser source is viewed through magnifying instruments. Class 2 covers only low-power visible-beam lasers for which protection of the eyes from accidental exposure is provided by our natural aversion response to a sudden bright light (closing the eyes and turning away), thereby limiting the period of exposure. Class 3R lasers can be hazardous to the eyes if the beam is viewed directly, while Class 3B represents a serious risk of injury to the eyes, even for a very brief, momentary exposure.

A broadly similar system of laser classification is used in the USA, with classes designated I, IIa, II, IIIa, IIIb and IV, but the detailed classification rules and requirements differ in important respects from those used in the IEC and EN standards. It is important that lasers are classified in accordance with the geographical location in which they are sold and used, and this obviously has an impact on imported laser products.

Safe laser equipment

Laser equipment should be properly labelled to indicate its class and to warn users of its potential hazard. It must also comply with various manufacturing requirements that are specified in the safety standard and which depend on its classification. These include specific details of the engineering design and the need for adequate safety documentation. Additional safety provisions apply to certain kinds of laser products, including medical lasers, optical-fibre communication systems and industrial laser processing machines. Those who manufacture equipment, systems or products that incorporate a laser may need to seek advice on safety compliance.

Laser equipment sold in the USA has to satisfy criteria laid down by the FDA in the Federal Performance Standard for Laser Products, 21 CFR 1040.10 & 1040.11. (The FDA will, however, accept products that meet specified provisions, including classification and labelling, of the IEC standard.) A Laser Product Report detailing how compliance has been achieved must be submitted and an accession number granted for all laser products that are sold in the USA.

Using lasers safely

While the class of a laser gives a general indication of the degree of hazard and of the type of precautions that may be necessary, the effective control of laser hazards often requires a risk assessment to determine the precise nature of these hazards and to identify the conditions under which actual harm may be caused. Guidance is given in the international safety standard PD IEC TR 60825-14 (Safety of laser products – Part 14: A user’s guide).

A risk assessment needs to take into account the specification (including the class) of the laser equipment, the nature of its potential hazards, the purpose for which the equipment is being used, the environment in which it is being operated and the people who are involved. Appropriate engineering safeguards, administrative control procedures and personal protection should then be used to reduce the risk of injury, with the emphasis on engineered protection (such as beam enclosures) and on safe systems of work (often called ‘local rules’). Significant findings of the risk assessment and the means adopted for controlling the risks should be documented.

Only people who have been appropriately trained should work with lasers in the higher classes (particularly classes 3B and 4), and all such work should normally be carried out in controlled areas having restricted acces. A Laser Safety Officer (LSO) should also be appointed. The LSO (usually called the Laser Protection Supervisor in the healthcare and cosmetic sector) is responsible, on behalf of the employer, for the day-to-day management of laser safety. More specialised advice should be sought from an external Laser Protection Adviser (LPA). The use of an accredited LPA is mandatory for users of lasers and intense pulsed light (IPL) sources in the healthcare & cosmetic sector under the National Minimum Standards, which are administered in England and Wales by the Healthcare Commission.

Laser eye protection

Laser eye-protection, although often regarded as an important aid to laser safety, should only be used where it is not possible to adequately control the risk by a combination of engineering controls and safe systems of work. Where it is used, eye-protection must be properly specified for the exposure conditions that could occur, and its use should be governed by a strictly-enforced written policy. In Europe, laser eye protection has to conform to either EN 207 (for full protection) or EN 208 (when using lasers having visible emission where it is necessary to be able to see the beam, such as when carrying out beam alignment). The eye protection must be CE-marked to indicate compliance with European legislation. The specification of the eye protection that is needed depends on the particular characteristics of the laser that is being used. This includes the laser wavelength, the time characteristics of the emission (i.e. whether it is pulsed or continuous), and the maximum power- or energy-concentration (the irradiance or radiant exposure).

Safety training

Anyone working with, or responsible for, potentially hazardous laser equipment should have appropriate training in laser safety. They should be aware of the nature of laser hazards and understand the procedures and safeguards that need to be implemented. Some (including Laser Safety Officers) will need a more detailed understanding of the safety issues.

Employers have a legal responsibility to establish adequate written workplace policies for the management and control of risks arising from the use of laser equipment, and to ensure that their employees are properly informed about the nature of the hazards.

For more information

For more detailed information about laser safety talk to Bioptica. We can help you to assess the hazards of your laser equipment and implement appropriate safety controls and protective measures. We can assist you in complying with applicable safety standards and regulations. We can provide safety training to ensure that your staff understand the nature of laser hazards and know how to work safely.

To find out more about laser safety you can also obtain a copy of our 450-page book: LASER SAFETY (ISBN 0 7503 0859 1). This comprehensive handbook, covering international requirements in laser safety and discussing in detail the nature of laser hazards, the classification procedures for laser equipment and the practical implementation of safety controls, has been written by Roy Henderson and Karl Schulmeister. It is available through any bookstore or direct from the publisher, Taylor & Francis.