Laser Safety

Table of contents

1.   Introduction

2.   Responsibilities

    (a) Head of department

    (b) Research supervisors

    (c) Laser users

    (d) Department laser supervisor (DLS)

    (e) University Laser Safety Officer (ULSO)

3.   Laser registration

4.   Hazards

    (a) Beam hazards

    (b) Non-beam hazards

5.   Risk assessment

6.   Controls

    (a) Engineering control

    (b) Administrative control

    (c) Personal protective equipment (PPE)

7.   Laser pointers

8.   Ophthalmic examinations

1. Introduction

There are currently no statutory regulations specific to laser safety but their use is covered by the general requirements of the Health and Safety at Work etc Act 1974. In addition the Management of Health and Safety at Work Regulations 1999 require that a risk assessment of the work activity is undertaken, that significant findings are recorded, and that appropriate control measures are implemented.

The standard of assessment and control is outlined within various British Standards, most notably:

(a)  PD IEC TR 60825-14:2004  Safety of laser products part 14: A users guide

(b)  BS EN 60825-4:2006  Safety of laser products part 4: Laser guards

(c)  PD IEC/TR 60825-8:2006  Safety of laser products part 8: Guidelines for the safe use of laser beams on humans

(d)  BS EN 207:1999  Personal eye-protection filters and eye-protectors against laser radiation (eye protection)

(e)  BS EN 208:1999  Personal eye-protection eye protection for adjustment work on lasers and laser systems (laser adjustment eye-protectors)

Failure to manage lasers safely can lead to serious irreversible consequences with the damage occurring in a very short period of time. Of particular concern is the potential injury that can be caused to the eyes by the focusing of the radiation onto the retina. Due to the seriousness of the injury and in acknowledgement of previous incidents within the University, this policy details the specific requirements in order to ensure legislative requirements are met.

The policy relates to all lasers, EXCEPT inherently safe Class 1 products (e.g. laser printers, CD players etc) or laser pointers below Class 3. It includes Class 1 by design equipment that has embedded Class 3 or 4 lasers, if the higher-class laser beam is exposed during service and maintenance. The extent to which individuals need to be authorised and trained depends upon their exposure to the beam or other significant risks.

2. Responsibilities

(a)  Head of department

(i)  Heads of Department are responsible for ensuring that all lasers within their department are operated in accordance with this policy.

(ii)  Heads of Department, where appropriate, are responsible for identifying a suitable person to act as Departmental Laser Supervisor. The appointment should be confirmed in writing and documented within the departments Statement of Health and Safety Organisation.

(b)  Research supervisors

(i)  Research supervisors are responsible for ensuring their lasers are operated in accordance with this policy.

(ii)  Research supervisors are responsible for registering all lasers with the Departmental Laser Supervisor.

(iii)  Research supervisors are responsible for ensuring lasers are correctly classified.

(iv)  Research supervisors are responsible for undertaking a suitable risk assessment and implementing appropriate controls before the system is operated.

(v)  Research supervisors are responsible for authorising any new laser user.

(vi)  Research supervisors are responsible for ensuring laser users are trained in accordance with this policy.

(vii)  Research supervisors are responsible for maintaining a training record for each laser user, which identifies the processes they are deemed competent to undertake.

(viii)  Research supervisors are responsible for monitoring the use of lasers to ensure they are operated in accordance with the local rules.

(ix)  Research supervisors are responsible for reviewing the risk assessment, local rules and operating arrangements on an annual basis.

(c)  Laser users

(i)  Laser users must make themselves aware of the requirements of the local rules and seek clarification if these are not fully understood.

(ii)  Laser users must comply with the requirements of the local rules or immediately highlight problems to their supervisors when these cannot be met.

(iii)  Laser users must attend training as identified by their supervisor.

(iv)  Laser users must not undertake procedures that they have not been suitably trained or authorised to undertake, or undertake without appropriate supervision.

(v)  Laser users must use and maintain any personal protective equipment that has been identified during a risk assessment.

(d)  Departmental laser supervisor (DLS)

(i)  A DLS must be appointed, by the head of department, whenever Class 3 or above lasers are operated, including any embedded laser in a lower class product that might be exposed during routine servicing or maintenance.

(ii)  The DLS is responsible for maintaining a record of all relevant lasers in the department.

(iii)  The DLS is responsible for providing advice to research supervisors on the process of laser risk assessment and the appropriate level of control.

(iv)  The DLS is responsible for ensuring all lasers are appropriately labelled.

(v)  The DLS is responsible for providing guidance or, if appropriate, direct training on the use of lasers.

(vi)  The DLS is responsible for providing advice on the correct selection of personal protective equipment.

(vii)  The DLS is responsible for carrying out an annual inspection of all lasers and must report the findings through the Departmental Safety Advisory Committee to the head of department, with a copy to the University Safety Office.

(viii)  The DLS should seek assistance from the University Safety Office and the University Laser Safety Officer for clarification on laser safety.

(e)  University Laser Safety Officer (ULSO)

(i)  The ULSO is appointed by the Director of the University Safety Office.

(ii)  The ULSO is responsible for providing advice to departments on the implementation of this policy in relation to relevant legislation and British Standards.

(iii)  The ULSO is responsible for maintaining a University inventory of relevant lasers.

(iv)  The ULSO is responsible for providing advice to departments on appropriate risk assessments and the required level of control.

(v)  The ULSO is responsible for coordinating University wide training on lasers.

3. Laser registration

A laser inventory must be maintained by the DLS for all lasers, except inherently safe Class 1 lasers (e.g. laser printers, CD players etc) and laser pointers below Class 3. The inventory must include Class 1 by design products that have embedded Class 3 or 4 lasers whose beams might be exposed during routine service and maintenance.

Supervisors must ensure that all relevant lasers under their control are registered with the DLS. In particular, they must notify the DLS before use of any new laser. This includes those that are obtained from other departments and also any laser that is temporarily on loan or to be used by contractors to undergo specific activities (e.g. cleaning or display).

All lasers must conform to BS EN 60825-1 [or other relevant standards] and an overview of the details must be given to the DLS. The Laser Registration Form (LS-1)in Appendix 1 can be used for this purpose.

The DLS must forward an updated version of the inventory to the University Safety Office on an annual basis. The Laser inventory proformain Appendix 5 can be used.

4. Hazards

(a)  Beam hazards

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 dependant upon the wavelength and output power. Further details are highlighted in Appendix 7.

Exposure to laser beams must therefore be within prescribed safe limits for both eye and skin exposure. These limits are set within PD IEC TR 60825-14:2004 and are referred to as the Maximum Permissible Exposure (MPE). Lasers are classified according to their potential to exceed the MPE and range from Class 1 (normally safe) to Class 4 (pose a serious risk of injury from direct or even diffuse reflections, along with the potential to cause fire). Full details of the classification system and the associated risk are given within Appendix 8.

All lasers introduced into the University after 2002 must be classified according to the system outlined in Appendix 8. Before 2002, a different system of classification was used. It is sufficient to refer to the previous classification system when completing risk assessments, but individuals using lasers classified under the pre-2002 system must be suitably trained in the different classifications.

Lasers and laser products supplied by manufacturers from within the EU will be classified according to the system in Appendix 8. Departments who make lasers or obtain lasers from non-EU suppliers must ensure that they are properly classified and meet all relevant European Standards. This is a complex matter and although the use of commercially available software can be used as an aide to classification (software is available via the University Safety Office), departments may need to obtain external assistance in order to ensure that the full requirements of BS EN 60825-1 and other standards are met.

(b)  Non-beam hazards

The operation of lasers encompasses a whole range of non-beam hazards that often pose a greater risk than the beam itself. The types of hazards normally encountered are highlighted in Appendix 6 - Guidance to Laser Risk Assessment. Many of these hazards are covered in detail within other University Policy Statements (eg Electricity S4/10, Compressed gases S7/00, Liquid nitrogen S4/03, Manual handling S7/99, Noise S1/06). However, they are often directly linked with the operation of the laser beam itself, so they should always be included in any overall assessment of the laser system.

5. Risk assessment

In line with the Management of Health & Safety at Work regulations, the risks associated with laser systems must be suitably and sufficiently assessed. The purpose of the assessment is to systematically identify all hazards associated with the laser system and assess the risk arising from both normal and/or non-routine use.

As a minimum, a written risk assessment is required for:

(a)  Any class 3R, 3B or 4 laser.

(b)  Any manipulation of a lower class laser that might increase the risk under certain operating conditions (e.g. use of magnifying instruments).

(c)  Any lower class laser whose non-beam hazards pose a significant risk, even though the risk from the beam itself is negligible.

(d)  Embedded Class 1 by design products encompassing Class 3 or 4 lasers if the beams might be exposed during routine service and maintenance. If a contractor is carrying out this service, then the contractor should be asked to supply their own risk assessment and method statement, but this should be reviewed in line with the departments own arrangements (see University Policy Statement S6/08 for further details).

The risk assessment must identify appropriate engineering controls, administrative controls and, if risks still then exist, personal protective equipment. It must be completed prior to the installation or first use of the laser and must include consideration of both beam and non-beam hazards. In order to achieve a standard approach to laser risk assessment, the Laser Registration Form (LS-1) in Appendix 1 and Laser Risk Assessment Form (LS-2) in Appendix 2 can be used, following the detailed guidance given in Appendix 6.

6. Controls

The British Standard of control for the normal operation of lasers is given in Appendix 9. These minimum requirements must be met.

Where an assessment identifies a specific risk with the laser system, then a hierarchy of control must be followed. For non-beam hazards these are outlined within individual University Policy Statements. For beam hazards, the preferred starting point for all lasers is fully enclosed with fixed guarding.

If a risk assessment identifies that it is not practical to fully enclose the laser at all times, then it must be justified within the assessment and a suitable combination of engineering, administrative and personal protective controls identified. In any event, the use of personal protective equipment must always be the last option and if it is necessary, there must be clear administrative controls to ensure it is correctly applied.

It is important to identify controls that are not overly complicated. A balance needs to be met between ensuring the safety of individuals and avoiding making procedures so complicated that they are difficult to apply. Equally, it is important to avoid introducing confusing arrangements, such as the use of personal protective equipment where the risk from a beam is either unlikely or of inadequate power (e.g. use of Class 1 or 2 lasers).

Further details of the hierarchy of control are given below:

(a)  Engineering control

The following outlines general levels of engineering controls. As stated the preferred starting point for all lasers is fully enclosed with fixed guarding, but the assessment should identify what level or combination of controls is relevant.

(i)  Fully enclosed with fixed guarding

  • This would result in a Class 1 by design product.  
  • Guarding should be in line with BS EN 60825-4  
  • Guarding should ideally be localised to the beam(s) itself, such as the use of optical fibres, fixed flight tubes or enclosures directly secured around the beam.  
  • Guarding may encompass the whole laser system, such as the use of polycarbonate or acrylic screens of suitable optical protection for the laser in use.  
  • Guarding must be robust, secure, and fit for purpose. The material used should be appropriate to the laser classification. For lower class lasers, where the guarding is simply to avoid intrabeam (i.e. direct) viewing, then certain plastics or MDF could be appropriate. For Class 3B or 4 lasers, where there is an added risk from reflectance or scatter, then appropriate metal guarding should be used to ensure containment of the beam.  
  • Guarding should be secured into position with screws that limit ease of removal, such as the use of tamper-resistant screw heads or at the very least, less common screw heads such as Torx or Tri-wing.

(ii)  Fully enclosed with removable interlocked guarding

  • This would result in a Class 1 by design product.  
  • Where guarding may need to be opened, for instance to permit alignment, then interlocks must be fitted which connect either to a laser shutter or power supply. Override systems may be used to enable alignment to take place, but these must be used in conjunction with clear administrative controls and where necessary, personal protective equipment.  
  • Interlocks must be designed so as to fail to safe. Proprietary interlock systems are recommended, but in-house developed interlocks may be used provided they comply with the general requirements of BS EN 60825-4.  
  • Interlocks must require some form of positive action for resetting, such that they will not automatically trigger the beam when closed.

(iii)  Enclosed with removable guarding

  • Localised guarding, of suitable material, secured into position to restrict access to an open beam. The guards though can be removed where necessary to expose the beam. For instance, where side shields are used, top covers can be applied to not only reduce exposure to the beam, but also help protect the optics.  
  • Such guarding must be used in conjunction with appropriate administrative controls and, where necessary, personal protective equipment.  
  • Guarding should, where possible, be compartmentalised to limit the amount of beam that needs to be exposed at any one time.  
  • If flight tubes are used, they should be of suitable robust construction and appropriately secured. Two or more fixed clamps must be used to secure the tubes and gravity-held shutters should be used as connectors so the beam path is closed when the tubes are removed.

(iv)  Horizontal beam lines with side shields on tables

  • If localised enclosures/guarding is not possible, then as a minimum all laser tables must be fitted with appropriate side shields.

(v)  Laser controlled areas

  • Wherever there is potential exposure to a laser beam that could result in a reasonably foreseeable risk of harm, then that area must be designated a Laser Controlled Area.  
  • Laser controlled areas might encompass any of the above types of engineering controls.  
  • Laser controlled areas may be the enclosure itself or the room in which a laser is sited. In any event, the boundaries of such an area must be clearly defined and physically identified.  
  • Wherever access is required into a Laser Controlled Area, it must be accompanied by appropriate administrative controls and where necessary, personal protective equipment.  
  • Where the Laser Controlled Area is a room, then the following is required:
  • The entry door(s) must have an appropriate security device (e.g. swipe card system or number lock) to restrict access to authorised persons only. 
  • An interlock device should be in place on the entry door(s), unless the risk assessment indicates otherwise, so that the beam is stopped when the door is opened. The interlock should be connected either to the power supply of the laser or to a shutter on the output aperture of the laser.  The use of an override system on the interlock must be carefully considered and must be accompanied by appropriate administrative controls.  
  • Entry door interlock systems should be accompanied with emergency buttons, which when operated disable the door locks and simultaneously cut the power to the lasers.  
  • There must be a visual warning at the entrance to a controlled area, normally linked into the laser operation.  
  • The laser and associated components should be securely fixed.  
  • There must be a high level of general illumination in the room.  
  • Walls, ceilings, and fittings should be painted with a light coloured matt paint to enhance illumination and minimise specular reflections. The use of reflecting surfaces, such as glass-fronted cupboards, should be avoided  
  • Adequate ventilation of the lasing material and target should be provided.  
  • Fire fighting equipment for the room must be provided.

(vi)  Other engineering controls

  • Beams must, wherever possible, be held in the horizontal plane either significantly below or significantly above the operators eye line. If a beam path must change level, then initial consideration must be given to increasing the height of the equipment, before the introduction of any periscope. If a periscope is absolutely required, then the Departmental Laser Supervisor must be satisfied that the optics are sufficiently rigid to prevent movement and a fixed beam stop placed at the top of the periscope to prevent someone looking directly into the beam. The periscope system from the Department of Physics is the recommended design.  
  • All Class 3B and Class 4 lasers must be fitted with a shutter. However, where the risk assessment identifies that the existing shutter is not suitable, then additional shutters should be introduced. For instance some lasers are fitted with manually operated shutters, which cannot be linked into an interlock system. In this case, it might be necessary to fit additional electrically operated shutters, but again these must comply with BS EN 60825-1.  
  • All Class 3B and Class 4 lasers must be fitted with key control systems to prevent unauthorised persons operating the laser. When a laser is not in use, the keys must be removed and kept in a secure area, such as a locked key press or drawer. Laser shutters should only be used for control of lasers over short periods of time. When lasers are not required for long or extended periods, they should be switched off.  
  • Laser beams of Class 3R and above (and when magnifying instruments are used with Class 1M and 2M) should be terminated at the end of their useful paths using a suitable beam stop. If this is not practicable, then additional administrative control and if necessary, suitable personal protective equipment must be worn by all those present in the area.

(b)  Administrative control

(i)  Local rules

  • Where engineering controls are not adequate to fully control the associated risks with a laser beam, then there will be a requirement for specified procedures to ensure individuals minimise the risk. The risk assessment should identify the additional precautions that are required and these must be recorded as Local Rules for the laser system.  
  • In general, local rules will be required for Class 3R and above lasers or any other location identified as a Laser Controlled Area. Both the Supervisor and Departmental Laser Supervisor must approve the local rules and a copy must be displayed at the entrance(s) to a Laser Controlled Area.  
  • In addition to the Laser Registration Form (LS-1) in Appendix 1 and Laser Risk Assessment Form (LS-2) in Appendix 2, the Laser Local Rules (LS-3) in Appendix 3 can be used for this purpose, following the guidance for completing these rules given in Appendix 10.

 (ii)  Authorised users

  • Only suitably trained individuals are permitted to work with open laser beams.  
  • The supervisor must identify the appropriate level of training required and outline these requirements within Section 1 of the local rules.  
  • Where a level of risk differs depending on the various laser operations (e.g. during alignment), then additional training requirements must also be outlined within Section 1 of the local rules.  
  • Laser Users must be authorised by their Supervisor before operating a laser and an individual training record must be maintained. The Laser User Authorisation/Training Record (LS-4) in Appendix 4 can be used for this purpose.  
  • The training record must give an indication of the competency of an individual, as assessed by the supervisor. This includes individuals who have received training in other departments or establishments.  
  • Consideration must also be given to the competency of visitors and contractors before permitting access to lasers.

 (iii)  Signage and warning signs

  • In line with University Policy Statement S9/07, appropriate safety signs must be displayed whenever there is a risk to health and safety that cannot be avoided or controlled by other means.  
  • The signs must be in accordance with University Policy Statement S9/07 and so any non-compliant signs (e.g. from non-EU suppliers) must be replaced. Appropriate warning signs are available from the University Safety Office.  
  • The entry point(s) to a Laser Controlled Area must be marked with:   
  • Hazard warning symbol, bearing the laser starburst pictogram.     
  • Prohibition sign indicating restriction to authorised personnel only.     
  • Indication of the highest class of laser in the area.     
  • Local rules.     
  • Other suitable signs, as identified within the risk assessment.
  • If illuminated warning signs are used these should clearly state when it is safe, or not safe, to enter.  
  • On the laser itself, there must be sufficient and appropriate warning labels, indicating the class of laser and the relevant supplementary information as described in Appendix 11. Labels are available from the University Safety Office.

 (iv)  Emergency contingency plans

Following any incident involving potential exposures above the Maximum Permissible Exposure, an individual must receive urgent medical attention from an ophthalmologist at the John Radcliffe Eye Hospital, who should undertake a full ophthalmic examination within 24 hours of being notified.

A copy of the Laser Registration Form must be sent with the individual, so that the laser details are available to the ophthalmologist in order to make the appropriate examination.

The University Safety Office must also be informed. Any eye injury caused by a laser is reportable to the Health and Safety Executive under the Reporting of Injuries, Diseases, and Dangerous Occurrences Regulations 1995. Oncethe area has been made safe, the state of the room must remain undisturbed, in case a follow-up inspection is required.

 (c)  Personal protective equipment (PPE)

Personal protective equipment in the context of laser safety normally implies the use of laser protective eyewear. As with any PPE though, there are serious limitations when relying on laser protective eyewear alone. Notably, it requires careful selection against all possible wavelengths and as such, this could result in the need for more than one type of protective eyewear to cover all potential operating conditions. It also requires very careful training and supervision to ensure the eyewear is actually worn, particularly as laser eyewear, by its nature, will reduce normal viewing as well. In some cases, this will actually increase the risk, as people might be unable to see the beam or indeed any other non-beam hazard. Most importantly, when laser eye protection is required, it generally implies there is both an eye and a skin hazard. The risk to the skin must not be discounted, although the options for protection are significantly less.

Finally, if we assume that more than one person at any one time is likely to require suitable eye protection, the actual cost of implementing personal eye protection may be greater than the cost of implementing appropriate guarding and administrative controls, albeit with a lower level of confidence in its control.

To reiterate, personal protective eyewear must only be used where engineering and administrative controls cannot adequately control the risk.

 (i)  Laser eye protection

Laser eye protection can be in the form of either spectacles (with frames that rest on the ears) or goggles (secured by a band around the head). The latter are more suitable for those who already wear spectacles, although it is possible to incorporate the wearers own spectacle correction in the safety eyewear. Laser protective eyewear should be a comfortable fit to the face and should provide adequate protection from laser radiation that might be incident around the edges of the frames.

Laser eye protection utilises optical filters to reduce to safe levels the laser exposure that might otherwise impinge on the surface of the eye. Supervisors must ensure that any eye protection is suitable for protecting against all the particular wavelengths in use. It should at the same time provide an adequate level of ‘Visible Light Transmission to ensure that normal visual tasks are not unduly affected. They should also be capable of withstanding the maximum foreseeable laser exposure long enough for the wearers to take action to remove themselves from further risk.

British Standard BS EN 207 defines the requirements for laser eye protection to reduce any accidental eye exposure to below the level of the Maximum Permissible Exposure (MPE). However, it is sometimes desirable, with visible beams, to be able to see the beam for alignment purposes. British Standard BS EN 208 covers requirements for laser eye protection designed to reduce the exposure to the equivalent of a Class 2 laser, where protection is afforded by the natural aversion response.

Where laser eye protection is deemed necessary, then the following must be applied:

  • There must be a documented in-house assessment of the required specification of eyewear for each type of laser, taking into account the varying wavelengths used and the degree of optical clarity required.The assessment must state both the optical density and ‘scale factor1 attenuation for all relevant wavelengths. It is not appropriate to rely on laser equipment suppliers to undertake this assessment or specify eyewear. Eyewear must be selected against the relevant standard, BS EN 207 for general use and BS EN 208 for alignment procedures  
  • There must be evidence, either on the frames or in accompanying documents, that the eyewear used is CE marked and conforms to the required standard. Eyewear that does not meet these requirements must be replaced.  
  • The protective eyewear should be labelled indicating which laser(s) and wavelengths they are suitable for.  
  • Where multiple lasers are used in a single area, then each set of protective eyewear must be unambiguously marked to ensure correct selection for the relevant laser.  
  • When not in use, protective eyewear must be stored correctly to prevent damage. It must not be left on benches but stored in protective cases or suitable racking.  
  • Individuals must be trained in the selection, fitting, storage, and inspection of protective eyewear.

(ii)  Skin protection

Where there is a serious co-existent risk of skin injury from laser exposure, then protective eyewear should not be used but alternative means of providing protection (by total enclosure of the laser radiation or filter windows) should be adopted instead. If this is still not possible, then suitable gloves, goggles, face shields etc. should be selected and used.

7. Laser pointers

The use of Class 1 or 2 laser pointers is not covered by this policy as their use, even during presentations, is unlikely to pose a significant risk. Users should exercise caution though, so as to avoid pointing the beam at any individual.

Some laser pointers are now available with quoted output powers of up to, and even over, 50 mW, thus placing them in the higher class of lasers. These pose a signficant risk of injury, particularly as the liklihood 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 say, a red laser. A correctly classified low powered green laser pointer should still pose a low risk, but individuals may experience some form of after image when it is displayed on a projection screen, particularly when viewed from close-by. If the green laser pointer is incorrectly classified, particularly one that emits a pulse of energy, then the risk may be significant.

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 University Safety Office.

8. Ophthalmic examinations

The University does not require laser users to undergo routine ophthalmic examination, but departments must ensure that laser users who believe themselves to suffer from significant pathological conditions of the eye consult the University Occupational Health Service prior to commencing laser use. The user declaration in ‘Laser User Authorisation/Training Record (LS-4)’ in Appendix 4 can be used to highlight the importance of this issue to the laser user.