Laser Safety

Laser Safety

Laser Safety

Laser Safety

Regulations regarding the sale, ownership and use of lasers vary around the world.
This site is UK based and the guidance below is based on the Public Health England (PHE) advice available in January 2016. This advice is highlighted in blue. The PHE link at the end of this section goes to their advice pages for further information.

The International Laser Display Association (ILDA) is the trade body for laser light shows and is supporting a non-commercial site concerned with the safety issues relating to laser pointers, we encourage owners and potential owners to take a look at: www.laserpointersafety.org

 

Laser Radiation

Lasers are devices which produce radiation with unique properties. It is these properties that distinguish laser radiation from the radiation produced by more familiar sources such as the sun or the common household electric light bulb.

When the radiation emitted by a source can be detected by the eye and produces a sensation of vision, it is referred to as light. An electric light bulb produces radiation comprising many different wavelengths, perceived as white light, and emits fairly equally in all directions.

The radiation produced is said to be highly divergent, ie the light spreads out rapidly as the observer moves away from the bulb. It is this property which allows the illumination of large areas using a single light bulb. In contrast a laser will produce radiation over a very narrow wavelength band, so narrow that the laser is referred to as a monochromatic or single wavelength source.

If the laser emits in the visible region then the radiation is perceived as a single colour. The wavelength of light is usually measured in nanometres, or one-thousand-millionth of a metre and is abbreviated to “nm”.

The laser also produces a very narrow beam which diverges, or spreads out, very little with increasing distance from the source. This low divergence property means that the laser output is highly directional, forming a pencil-like beam that will still appear as a small spot when shone against a surface, even at large distances (ie 100 metres plus).

A consequence of this is that high power devices can present a hazard over considerable distances. When considering the safety implications of the laser beam an important parameter is the amount of power in the beam divided by the cross-sectional area of the beam. This is called the irradiance and is usually quoted in watts per square metre or W m -2.

Laser Classification

The classification schemes for lasers indicates the potential risk of adverse health effects. Depending upon the conditions of use, exposure time or environment, these risks may or may not actually lead to adverse health effects. With the help of classification, users may select appropriate control measures to minimise these risks.

The classification of lasers is based on the concept of accessible emission limit (AEL); an AEL is defined for each laser class, except Class 4. The AEL takes into account not only the output of the laser product but also human access to the laser emission. Lasers are grouped into eight classes: the higher the class, the greater the potential to cause harm. The risk could be greatly reduced by additional user protective measures, including engineering controls such as enclosures.

The following laser classification scheme is taken from BS EN 60825-1

Class 1 lasers are products where the radiant power of the laser beam accessible (the accessible emission) is always below or equal to the Maximum Permissible Exposure value. Therefore, for Class 1 lasers the output power is below the level at which it is believed eye damage will occur. Exposure to the beam of a Class 1 laser will not result in eye injury. Class 1 lasers may therefore be considered safe. However, Class 1 laser products may contain laser systems of a higher Class but there are adequate engineering control measures to ensure that access to the beam is not reasonably likely during normal use. Examples of such products include laser printers and compact disc players.

Class 1M lasers are products which produce either a highly divergent beam or a large diameter beam. Therefore, only a small part of the whole laser beam can enter the eye. However, these laser products can be harmful to the eye if the beam is viewed using magnifying optical instruments. Some of the lasers used for fibre-optic communication systems are Class 1M laser products.

Class 2 lasers are limited to a maximum output power of 1 milliwatt (abbreviated to mW, one thousandth of a watt) and the beam must have a wavelength between 400 and 700 nm. A person receiving an eye exposure from a Class 2 laser beam, either accidentally or as a result of someone else's deliberate action (misuse) will be protected from injury by their own natural aversion response. This is a natural involuntary response that causes the individual to blink and avert their head thereby terminating the eye exposure. Repeated, deliberate exposure to the laser beam may not be safe. Some laser pointers and barcode scanners are Class 2 laser products.

Class 2M lasers are products which produce either a highly divergent beam or a large diameter beam within the wavelength range 400 to 700 nm. Therefore, only a small part of the whole laser beam can enter the eye and this is limited to 1 mW, similar to a Class 2 laser product. However, these products can be harmful to the eye if the beam is viewed using magnifying optical instruments or for long periods of time. Some lasers used for civil engineering applications, such as level and orientation instruments are Class 2M laser products.

Class 3R lasers are higher powered devices than Class 1 and Class 2 and may have a maximum output power of 5 mW or five times the Accessible Emission Limit (AEL) for a Class 1 product. The laser beams from these products exceed the maximum permissible exposure for accidental viewing and can potentially cause eye injuries, but the actual risk of injury following a short, accidental exposure, is still low.

Class 3B lasers may have an output power of up to 500 mW (half a watt). Class 3B lasers may have sufficient power to cause an eye injury, both from the direct beam and from reflections. The higher the output power of the device the greater the risk of injury. Class 3B lasers are therefore considered hazardous to the eye. However, the extent and severity of any eye injury arising from an exposure to the laser beam of a Class 3B laser will depend upon several factors including the radiant power entering the eye and the duration of the exposure. Examples of Class 3B products include lasers used for physiotherapy treatments and many research lasers.

Class 4 lasers have an output power greater than 500 mW (half a watt). There is no upper restriction on output power. Class 4 lasers are capable of causing injury to both the eye and skin and will also present a fire hazard if sufficiently high output powers are used. A class 4 laser product or application will need specific safety precautions for safe use. Lasers used for many laser displays, laser surgery and cutting metals may be Class 4 products. Many Class 4 laser products are safe during normal use, but may not have all of the protection measures required for a Class 1 product. An example would be an enclosure with an open roof; it is possible that someone could get a ladder and climb over the enclosure to get access to the laser beam.

 

Why Do Some Lasers Have The Class In Roman Numerals?

In the United States of America it is a legal requirement for laser products to comply with the requirements of a Federal Product Performance Standard. Lasers classified in accordance with this Standard are assigned to Classes I, IIA, II, IIIA, IIIB or IV. There are subtle differences between this Standard and the British Standard. This has caused a great deal of confusion with laser products labeled to the American Standard.

 

Classification of Laser Diodes and Laser Modules

Laser diodes and laser modules are supplied as OEM components (or unfinished products). The laser class will depend on the eventual application e.g. the power supply used, the housing, safety features etc. A laser warning sticker with the appropriate laser class should be added to the final product. In our descriptions we describe the original OEM class of the component which does not consider the final application.

These devices have been designed as complete laser components for OEM use and although their output powers have been set in accordance with BS(EN)60825 they are not certified lasers as defined in the specification for a final product. When incorporated into a piece of equipment, it may be necessary for additional safety features to be added before the equipment fully complies with the standard. Final classification will be dependent on the way the laser is used within the product, including access to the laser component and beam. Any final product that incorporates a laser must be certified in its own right, irrespective of whether the incorporated laser is certified or not by the manufacturer.

When incorporated into a final product as part of the process of CE marking, all laser and LED products sold in Europe must be certified to EN 60825-1. Manufacturers can self certify their equipment to EN 60825-1, however, many manufacturers prefer to have independent verification of their compliance with the classification requirements.

 

Regulations

There is no specific legislation covering the private use of lasers in the UK.

In the workplace the European Directive 2006/25/EC - Artificial Optical Radiation came into force in 2006. It was implemented in the UK as the Control of Arificial Optical Radiation at Work Regulations 2010. In addition, general safety legislation will apply, such as the Health and Safety at Work Act 1974, the Management of Health and Safety at Work Regulations 1999, the Provision and Use of Work Equipment Regulations 1998 and the Personal Protective Equipment at Work Regulations 1992. A suitable and sufficient assessment of the risks from the use of the lasers should be made by the employer.

Link for further information: http://news.hse.gov.uk/2010/04/30/the-control-of-artificial-optical-radiation-at-work-regulations-2010/

 

Laser Safety Standards

Laser safety standards are internationally agreed documents published by the International Electrotechnical Commission (IEC) – the international standards and conformity assessment body for all elds of electrotechnology. The standard is then usually adopted in Europe as a Euronorm and the UK edition is published by the British Standards Institution (BSI).

Applicable standard

      Outline of document

BS EN 60825‐1                  General laser safety

BS EN 60825‐2                  Optical fibre communications

PD IEC/TR 60825‐3           Laser displays

BS EN 60825‐4                  Laser guards

BS IEC 60825‐5                 Manufacturer’s checklist

BS EN 60825‐12                Free space optical communications

PD IEC/TR 60825‐13         Measurements for classification

PD IEC/TR 60825‐14         User’s guide

BS EN 207 and 208           Eyewear

JSP 390 Part 1 and 2       Military laser safety

 

Do I Need Laser Safety Goggles?

From a legal point of view, the answer depends on where in the world you are working and what legislation is in force.
In the absence of legislation our safety procedure is that for any situation where you could reasonably be expected to be exposed to lasers of Class 3B or higher appropriate goggles should be worn.

Eyewear is rated for optical density (OD), which is the base-10 logarithm of the attenuation factor by which the optical filter reduces beam power. For example, eyewear with OD 3 will reduce the beam power in the specified wavelength range by a factor of 1,000.

Eyewear must be selected for the specific type of laser, to block or attenuate in the appropriate wavelength range. For example, eyewear absorbing 532 nm typically has an orange appearance, transmitting wavelengths larger than 550 nm. Such eyewear would be useless as protection against a laser emitting at 800 nm. Furthermore, some lasers emit more than one wavelength of light, and this may be a particular problem with some less expensive frequency-doubled lasers, such as 532 nm "green laser pointers" which are commonly pumped by 808 nm infrared laser diodes, and also generate an intermediate 1064 nm laser beam which is used to produce the final 532 nm output. If the IR radiation is allowed into the beam, which happens in some green laser pointers, it will in general not be blocked by regular red or orange colored protective eyewear designed for pure green or already IR-filtered beam. We recommend our multiple wavelength goggles for green lasers since they protect against invisible IR emissions as well as the green laser light. For red lasers an alternative goggle is available.

Display Lasers

Laser light effects can, if used incorrectly, be very dangerous. All devices should be used in accordance with the HSE guidance publication HS(G)95 “The radiation safety of lasers used for display purposes” this is available free online in PDF format from    http://www.hse.gov.uk/pubns/priced/hsg95.pdf or from book stores under ISBN 978 0 7176 0691 7

The HSE publication referenced above contains useful information on calculating maximum exposure limits for laser display systems and procedures for assessing safe use.

 

Lithium Batteries

Lithium Polymer and Li-ion batteries are volatile. Failure to read and follow the below instructions may result in fire, personal injury and damage to property if charged or used improperly.

By purchasing Lithium Polymer and Li-ion batteries, the buyer assumes all risks associated with lithium batteries. If you do not agree with these conditions, please return the batteries immediately before use for refund.

Note: Batteries should not be mixed in equipment that takes more than one battery: Do not mix batteries with different specifications. Do not mix fully charged and partially charged batteries.

WEEE Compliance

You may return any unwanted batteries or electrical components supplied by us (or the item they are bought to replace) to us for disposal.
Most supermarkets and shops that sell batteries will have collection bins for used batteries, and some town halls, libraries or schools may also set up collection points. End-users may find stores in their local area more accessible.