Accessible Emission Limit (AEL)
The radiation level to which human access is possible, which must not be exceeded for a given class of laser. It is generally expressed as the total power or pulse energy output of the laser through a limiting aperture.
Beam divergence
The measure of increasing beam diameter, expressed as a linear angle, with distance of propagation. For beams with non-circular symmetry, beam divergence values in orthogonal planes may be specified.
Class 1 Laser products
Laser products that are normally safe under reasonably foreseeable conditions or use, either because the output of the laser source is sufficiently low, or by virtue of their engineering design e.g. total enclosure of the laser output.
Class 1C laser products
Laser product designed explicitly for contact application to the skin or other 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.
Class 1 (embedded) lasers
Laser products that contain a class 3B or class 4 laser but which, because of engineering features limiting accessible emissions, have been assigned as class 1. However, if these lasers are to be aligned, modified or serviced on site then additional precautions need to be taken as laid out in Appendix 8.
Class 1M laser products
Laser products that exceed the permitted accessible emission limits for class 1 but which are safe for viewing with the unaided eye. The output laser beam is reasonably collimated and has a large diameter, such that harmful exposure can occur under viewing with a telescope or binoculars.
Class 2 laser products
Laser products emitting low levels of visible radiation (i.e. in the wavelength range 400 nm to 700 nm) that are safe by virtue of the natural aversion response to bright light.
Class 2M laser products
Laser products emitting levels of visible radiation (i.e. in the wavelength range 400 nm to 700 nm) that exceed the permitted accessible emission limits for class 2 but which are safe for viewing with the unaided eye by virtue of the natural aversion response to bright light. The output laser beam is reasonably collimated and has a large diameter, such that harmful exposure can occur under viewing with a telescope or binoculars
Class 3B laser products
Medium power laser products for which direct ocular exposure is unsafe, but under certain conditions they may be safely viewed via a diffuse reflector. In general these safe conditions are:
- a minimum viewing distance of 130 mm and
- a maximum viewing time of 10 seconds
These lasers do not normally present a skin hazard.
Class 3R laser products
Laser products for which intra-beam viewing is potentially hazardous but the risk is low. For visible radiation (i.e. in the wavelength range 400 nm to 700 nm) the level of accessible emission can exceed the AEL for Class 2 by up to five times; for other wavelengths the level of accessible emission can exceed the AEL for Class 1 by up to five times.
Class 4 laser products
High-power laser products. In addition to the hazard from intra-beam viewing or specular reflections, they are capable of producing hazardous diffuse reflections, may cause skin injuries and could also present a fire hazard. Their use requires extreme caution
Continuous wave (CW)
The description used for a laser which produces a constant, as opposed to a pulsed laser output.
Designated laser area (DLA)
A room or other enclosed working area designed to contain lasers, such that there is no laser radiation hazard beyond the defined boundary of the area.
Diffuse reflection
The scattering of laser radiation from a rough surface.
Employee at particular risk
Any employee or group of employees whose health is at particular risk from exposure to artificial optical radiation.
Exposure limit value
Statutory limits on the exposure of employees (see 2006/25/EC). They represent the maximum levels to which the eye or skin can be exposed without risk of injury. Almost identical to the maximum permissible exposure values in BS EN 60825-1:2007, but different to those in BS EN 60825 1:2014. As legal limits on exposure the exposure limit values take precedence over the maximum permissible exposures.
Extended nominal ocular hazard distance (ENOHD)
The shortest distance (generally measured from the position of the laser source) at and beyond which a laser beam is safe for aided viewing.
Hazard level
The classification of fibre optic output at locations where interruption of the fibre might reasonably be foreseen, as described in BS EN 60825-2 ‘Safety of laser products: Part 2- Safety of optical fibre communication systems’. Hazard levels use the same nomenclature and warnings as is used for laser classes.
High hazard lasers
Class 3B and 4 laser products.
Human access
Capability for part of the human body to meet hazardous laser radiation.
Inherently safe
Safe by virtue of its inherently low emission of laser radiation. This contrasts with the emission from a Class 1 (embedded) laser product which is safe by engineering design.
Intra-beam viewing
The exposure of the eye to all or part of a laser beam, either directly or after specular reflection.
Irradiance
The radiant power incident on an element of a surface divided by the area of that element (Wcm-2). For normal incidence irradiation, this term is equal to the beam intensity at the surface.
Laser
(As defined in EN 60825-1) a device that can be made to produce or amplify electromagnetic radiation in the wavelength range from 180 nm to 1 mm primarily by the process of stimulated emission. ELV/MPE values do not exist for wavelengths outside this.
Laser hazard zone
The region around the laser and laser beam path within which, under all reasonably foreseeable conditions, a hazardous level of laser radiation may be present.
Laser nominated person (LNP)
A competent person appointed to carry out specified laser work.
Laser product
Any product or assembly of components that constitutes, incorporates or is intended to incorporate a laser or laser system.
Laser protection adviser (LPA)
A competent person, knowledgeable and experienced in laser safety matters, who is called upon to assist the OLRO in the performance of his or her duties. The LPA may be an employee or an external consultant.
Laser responsible officer (LRO)
A competent person appointed to take on specified duties and supervisory responsibilities in respect to a laser area or activity.
Laser system
A laser in combination with an appropriate laser energy source with or without additional incorporated components.
Low hazard lasers
Class 3R laser products Low risk lasers Class 1M, class 2, class 2M, class 1C and class 1 (embedded) laser products (including alignment lasers).
Maximum permissible exposure (MPE)
That level of laser radiation to which, in normal circumstances, persons may be exposed without suffering adverse effects. MPE values for eyes and skin exposures represent the maximum levels to which the eye or skin can be exposed without consequential injury. They vary with the wavelength of the radiation, the pulse duration or exposure time, the tissue at risk and, for visible and near-infrared radiation, the size of retinal image. The values are specified in BS EN 60825-1:2014 and forming the basis from which accessible emission limits for each laser class are defined. Similar to ELVs, but not identical.
Maintenance
Adjustments or procedures specified in the user information provided by the manufacturer/supplier with the laser product, which are performed by the user for the purposes of assuring the intended performance of the product. It may require access within the laser enclosure, but should not exposure the user to hazardous laser beams.
No risk lasers
Inherently class 1 or exempt laser products, and class 1 consumer products containing embedded lasers of higher class (e.g. laser printer, photocopier, compact disc or DVD player or recorder)
Nominal ocular hazard distance (NOHD)
The shortest distance (generally measured from the position of the laser source) at and beyond which a laser beam is safe for unaided viewing as the beam remains below the appropriate corneal ELV or MPE
Overall laser responsible officer (OLRO)
A competent person appointed by the authority of the director or equivalent, to oversee the control of laser radiation hazards and to be responsible for the implementation of this code with respect to a defined area of laser installations and/or equipment.
Personal protective equipment (PPE)
Protection that is worn or carried. This includes laser safety eyewear and protective clothing, such as gloves. Viewing windows and screens are not PPE.
Protective housing
Those portions of a laser product (including a product incorporating an embedded laser) that are designed to prevent human access to laser radiation in excess of the AEL prescribed for the product. (The laser product manufacturer generally installs the protective housing.)
Pulsed laser
(As defined in EN 60825-1) a laser that delivers its radiation output in the form of pulses with duration less than 0.25s, either singly or a train of pulses.
Pulse repetition frequency (PRF)
The number of pulses per second emitted by a pulsed laser.
Radiance
The radiant power per unit area of a radiating surface per unit solid angle of emission (Wsr-1m-2).
Radiant exposure
The radiant energy incident on an element of a surface divided by the area of that element (Jm-2).
Specular reflection
Reflection from a shiny surface, such as a mirror.
Standing orders (SO)
A set of formal written instructions that address all hazards and procedures for a specified location or piece of laser equipment.
