Laser Safety

Introduction

There are many potential hazards posed by working with lasers. The rules for the safe operation of lasers within the University are governed by British Standard 60825-1. This document supersedes the earlier booklet produced by the Committee of Vice Chancellors and Principals (CVCP) published in 1992, called 'Safety in Universities: Notes of Guidance". BS 60825-1 now forms the basis of the Code of Practice for those working with laser systems in the University of Leicester.

This web site outlines some of the key safety features for the safe operation of lasers. It is not intended to be a substitute for the more detailed BS-60825-1, copies of which are held by the University Laser Safety Officer (ULSO), who is currently Professor A. M. Ellis (mailto: andrew.ellis@le.ac.uk) from the Chemistry Department. The ULSO has several duties. One is to maintain a record of all laser systems of class 2 or higher (see later) within the university. Consequently, anyone who purchases a laser of class 2 or higher, including laser pointers, should inform the ULSO. Users of high intensity lasers, class 3B and 4, require prior authorisation by the ULSO, and must submit themselves for an eye test. Finally, the ULSO is available to provide advice on all aspects of laser safety, including the inspection of specific laser facilities. The role of the ULSO is to offer constructive, rather than obstructive, advice so you are strongly encouraged to contact him if you have any queries.

Hazards Associated with Lasers

The most obvious hazard is potential damage to eyesight. Lasers tend to be extremely bright sources of visible or invisible electromagnetic radiation. If suitable precautions are not taken, then permanent damage to the eyes is a distinct possibility. Skin damage is also another potential problem. The direct irradiation of skin by a highly intense laser can result in severe burns. However, even scattered radiation, especially in the ultraviolet, may need protecting against.

It is as well to remember that there are many other hazards indirectly associated with laser use. Many lasers employ lethal high voltage power supplies, and so care must be taken to ensure that they conform with all electrical safety guidelines. Details of other indirect hazards can be found in the BS 60825-1 booklet, but they include fire hazards and the possibility of toxic by-products being formed from certain uses of lasers.


Rules for Work with Laser Equipment

All work with lasers and associated equipment must comply with BS80625-1

There is no UK legislation specific to laser safety but their use is covered within the Health and Safety at Work Act. This Act places duties on employers as well as those who design, manufacture, install and use equipment including lasers to ensure that the health and safety of persons at work and other persons who may be affected are adequately protected.

Laser Classification

In order to define the potential hazard to eyes from lasers a classification system has been developed and refined which is summarised below. It is based on the concept of a maximum Accessible Emission Limit (AEL). Regardless of the intensity, if the laser light is totally enclosed within some container then the AEL is nominally zero. On the other hand, if the beam is not fully enclosed throughout its journey then the AEL will determine which class it belongs to. All commercial lasers should have a sticker on which specifies which class they belong to.

The introduction of BS 80625-1 has led to a new laser classification scheme. It is similar in many respects to the old scheme but has additional classes at the low intensity end of the scale. The new classification is shown in the table below.

CLASSPROTECTIVE MEASURESThese should be implemented unless a risk assessment justifying the adoption of alternative protective measures has been undertaken
1 Avoid prolonged eye exposure to the beam, if emission is accessible. In the case of embedded laser products containing a laser of higher class, follow instructions given on warning signs and supplied by the manufacturer. Special requirements apply to on-site servicing of embedded laser products.
1M Avoid prolonged eye exposure to the beam. Do not direct the beam at other people or into areas where other people unconnected with the laser work may be present.Ensure the beam is always terminated at a suitable non-specular (ie. non mirror-like) surface. Do not use any kind of magnifying viewing instrument (such as binoculars, telescopes, microscopes, optical sights or magnifying lenses) within the area in which the laser is being used. (Note. The product label may indicate the type of viewing aid which could be hazardous.)
2 Do not stare into the beam. Do not direct the beam at other people or into areas where other people unconnected with the laser work may be present.
2M Do not stare into the beam. Do not direct the beam at other people or into areas where other people unconnected with the laser work may be present. Ensure the beam is always terminated at a suitable non-specular (i.e. non mirror-like) surface. Do not use any kind of magnifying viewing instrument (such as binoculars,telescopes, microscopes, optical sights or magnifying lenses) within the areain which the laser is being used. (Note. The product label may indicate thetype of viewing aid which could be hazardous.)
3R Use only in an enclosed area.
Avoid direct eye exposure to the beam.
Ensure the beam is always terminated at a suitable non-specular (i.e. non mirror-like) surface. Do not direct the beam at other people or into areas where other people unconnected with the laser work may be present.
3B & 4 Class 3B and Class 4 laser products should not be used without first undertaking a risk assessment to determine the protective measures necessary to ensure safe operation.
Where reasonably practicable, use engineering means, as specified in IEC 60825-1, to reduce the class of the laser to below Class 3B. (This will normally mean completely enclosing the laser radiation to ensure Class 1 operation.)

All new lasers, particularly those manufactured in the EU, should come with labels on them stating which of the above classes they belong to. Lasers bought outside of the EU, along with older existing lasers, may still retain the older classification scheme shown in the table below.

CLASSDESCRIPTIONCOMMENTS
1 SAFE Either (1) output is so low it is inherently safe or (2) the laser is part of a totally enclosed system.
2 LOW POWER-visible CW and pulsed lasers In the case of CW lasers eye protection is normally afforded by the natural aversion responses including the blink reflex. Hazard can be controlled by relatively simple procedures.
3A LOW-MEDIUM POWER Extension of Class 2, where protection is still afforded by the natural aversion responses, but direct intrabeam viewing with optical aids may be hazardous. This must be controlled.
3B MEDIUM POWER Hazard from direct beam viewing and from specular reflections ( i.e. .off shiny surfaces). Eye damage can occur in less than 0.25 second. More detailed control measures are necessary.
4 HIGH POWER Not only a hazard from direct viewing and from specular reflections but also possible from diffuse reflections (off rough surfaces). May also ignite flammable materials. Extreme caution required.

Administrative Controls

These refer to those aspects of laser safety practice that are administrative in origin. They include proper registering of lasers and laser systems (see STARTING WORK WITH LASERS – WHAT DO I NEED TO DO?), any relevant training, knowledge of the laser safety code, the posting of adequate warning notices, and the provision of designated laser areas (see also ENGINEERING CONTROLS) and carrying out a risk assessment for the laser work planned.

In particular, a clearly written “Scheme of work” MUST be provided for operating specific laser systems.  This could be written by the laboratory supervisor or a research worker using the laser system.  Depending on the circumstances , it may be suitable to write this as a simple series of instructions, such as:

“Initial alignment must be carried out at the lowest practical operating power”

“Before switching on the laser and attempting alignment, a beam stop must be placed at location X”

For a more comprehensive example of a scheme of work, click the following link (scheme of work).

Preferably, the series of instructions in the scheme of work will be relatively concise, perhaps fitting even on a single side of A4 paper.  It is suggested that these are placed in or attached to the operation manual for the laser.  It is also a good idea to have a copy of these rules in a clearly visible location near the laser system for easy access, e.g. a laminated copy on a nearby wall.

For more specific information consult the BS 60825-1 booklet (contact your DLSO or the ULSO).

Engineering Controls

Engineering controls are an essential part of laser safety. They include features such as beam dumps, beam shields, and door interlocks. Engineering controls provide protection against inadvertent exposure to the laser beam. The beam dump serves to terminate the beam path at some appropriate point. The beam dump must be designed such that it is capable of absorbing the full intensity of the laser beam, i.e. there should be no significant backscattering and the dump must be fireproof. Similarly, it is desirable to ensure that as much as the beam path as possible is either fully or at least partly enclosed. Securely clamped plastic or metal tubes are a good means of transporting laser beams over significant distances without exposing the user to the risk of intrabeam viewing. If some access to the beam is required, then shields surrounding the beam path may be an acceptable substitute. Regions where a person can walk through part of the beam path, or even worse where he/she can accidentally bend down and look along the beam path, must be avoided at all costs.

Wherever possible, the optical path for the laser should be horizontal and well below eye level.

All work with class 3B and 4 lasers should be carried out in a Designated Laser Area (DLA). This is a clearly defined area that is set aside for laser use and where the hazards can be effectively controlled. In general this will be a specific room; a curtained off part of a laboratory will not normally suffice as a DLA. The DLAs must be clearly identified by a suitable warning notice. A visual signal outside the area, such as a red light, is also recommended.

For work involving open beam paths it is essential that all lasers be interlocked to protect against unauthorised access to the DLA. In other words, a switch must be fitted to the door such that, if an unauthorised person enters the DLA, the laser will be shutdown.  Alternatively, you can use secure key pad entry to a designated laser area.  Providing the access code is restricted to authorised users, this approach is an acceptable alternative to a fully interlocked door system.   Some items such as warning labels, beam dumps, and door interlocks, can be bought from commercial suppliers. Further details on Engineering Controls are available from the ULSO.

Safety Glasses

Safety glasses can be purchased which provide protection against accidental exposure to a particular laser beam. This is especially valuable when the user must make adjustments to one or more beams, for example to direct it into some external piece of equipment. However, you should recognise that, if the beam is a visible one and you require full protection against accidental exposure, then the safety glasses will make it impossible to see this beam. This clearly makes alignment very difficult!

In general, safety glasses should be regarded as a last resort, i.e. administrative and engineering controls should render them unnecessary in most cases. However, there are circumstances where they are valuable or even essential. When working with intense invisible lasers where the engineering controls do not afford full protection then wearing of appropriate safety glasses is not only a sensible precaution but is strongly recommended. Another example is when two laser beams are present, say an intense one and a less intense visible beam. Glasses that afford protection against exposure to the intense beam but allow the user to observe (on an alignment card) the less intense beam are a sensible precaution. Externally pumped tunable lasers, such as dye lasers and optical parametric oscillators, fall into this category. For these devices it is sensible to wear safety glasses that protect against accidental exposure to the intense pump beam (say from a Nd:YAG or excimer laser), particularly when adjustments are being made that affect the optical path of the pump beam. When carrying out alignment and/or adjustments of any laser it is recommended that you alwasys begin this process by working at the lowest practical laser intensity. However, even then the intensity may be dangerously high, so it may be appropriate to still wear safety glassess. Contact the ULSO if you have any queries.

There are several suppliers of laser safety glasses and goggles. The glasses/goggles need to be fitted with plastic or glass filters which block the desired wavelength(s) while retaining high transmission over as much of the visible region as possible. Furthermore, the supplier will need to know the output power (or for pulsed lasers the pulse energy and duration) in order to provide filters with an adequate optical density. The ULSO has information on suppliers of safety glasses and goggles.

Please be aware that laser safety glasses and safety goggles are next to useless if not correctly labelled.  It is good practice to make sure that the wavelength range protected and the optical density in this range is clearly specified so that there can be no confusion about the suitability of the glasses/goggles for a particular application. This information can either be made clear on the glasses/goggles (e.g. on the rim) or on the case in which the glasses/goggles are located. Please ensure that users get into the habit of putting the glasses/goggles back where they belong when not in use.

Damaged glasses/goggles should be discarded immediately.

Starting Work with Lasers - What do I need to do?

The laser(s)

All lasers, or indeed secondhand or borrowed ones, of class 3 or higher must be registered with the University Laser Safety Officer (mailto: andrew.ellis@le.ac.uk). This includes laser pointers if they are class 3 devices. It is also recommended that you register all class 2 lasers with the ULSO. A form for this registration is available by clicking on the relevant link below.

Laser registration form

Laser risk assessment form

Laser user registration form

You are strongly advised to contact the ULSO if your work requires you to employ class 3 or 4 lasers. If this is the first time that you have worked with such devices this is especially important. If necessary, the ULSO will visit your laboratory to discuss the implementation of the required safety precautions.

New laser users

The University requires all users of class 3B and 4 lasers to be officially registered. At the very minimum this requires:

  1. An eye test, which can be arranged by contacting the ULSO. There is no central budget to pay for these tests, so it is up to the user to specify who the invoice should be sent to. Typically this would be the department in which the user works.
  2. Familiarity with the BS 60825 guidelines for safe operation of lasers (booklet available from the ULSO).
  3. Signed statement of laser user responsibilities deposited with the ULSO (form available from the ULSO) or click on the following link. Laser user registration form.
  4. Risk Assessment - A risk assessent form must be completed for each of a class 3B or class 4 laser. The form should be signed by the laboratory supervisor and kept in a readily accessible location near the place of work. A copy should be sent to the ULSO. A copy of the form is available by clicking the following link. Laser risk assessment form.

Training

Because of the small number of new students and staff registering as operators of class 3B and 4 lasers, the University does not currently offer a formal, generic training course for new users each year.  One-on-one advice can be provided by the University Laser safety Officer (ULSO) where appropriate.  However, it is envisaged that the most effective training will be provided at the departmental or research-group level, and it is the responsibility of the Research Supervisor to arrange for this training.  The University is required by the HSE to maintain a central record of any such training (to be held by the ULSO), i.e. who has been trained to use a particular laser system and a brief description of what that training involved.  This recording process could be setup by the Research Supervisor as a proforma for repeat use, perhaps with a series of tick boxes for specific training tasks.  Notice also that the Laser User Registration form available from this web site has now been modified to include mention of training by the Research Supervisor (or other responsible person as appropriate).

Laser Pointers

Laser pointers are not exempt from the above requirements. Although their potential for eye damage is very small, there has been some concern in the technical press about class 3 laser pointers. More specifically, some lasers classified as IIIA (note the Roman numerals) under the American system may be class 3B lasers under the British system. If in any doubt these laser pointers should be withdrawn from further use. Further information is available from the National Radiological Protection Board (NRPB) at the following website (http://www.nrpb.org.uk/Is1-98.htm)

The University recommendation is that all new laser pointers should be class 2 devices.

Use of Lasers in Undergraduate Teaching & Research

Where possible, it is preferable to restrict undergraduate use of lasers to class 2 and 3R devices. An important part of student training is to ensure that undergraduates who use lasers are aware of the safety hazards and are trained to work with lasers in a safe and responsible manner.

 

If it is necessary for undergraduates to work with class 3B or 4 lasers that are not totally enclosed with adequate interlock protection, then they must first become registered laser users (see STARTING WORK WITH LASERS – WHAT DO I NEED TO DO?). The cost and time involved in the registration procedure means that, in practice, such work is likely to be restricted to undergraduate research projects.

 

Departmental Laser Safety Officers

Most departments do not have specific laser safety officers because they make little or no use of high intensity lasers. However, circumstances change and, especially if Class 3B or 4 lasers are used in teaching or research, then it is essential that the HOD appoints a Departmental Laser Safety Officer (DLSO). The list below identifies the current DLSOs.

  • Molecular Cell Biology – Dr Dmitry Cherny
  • Chemistry – Prof Andrew M. Ellis (also University Laser Safety Officer)
  • Engineering – Mr Paul Williams
  • Physics – Prof Richard Willingale
  • Neuroscience, Psychology and Behaviour - Prof Nicholas Hartell

 

Registered Lasers

The following lasers have been registered with the ULSO. If you are aware of any changes then please notify the ULSO as soon as possible.  Only Class 3 and Class 4 lasers are listed here.

Chemistry

Class 4

2 x Laser Vision OPO/OPA pumped by Continuum Surelite Nd:YAG laser

5 x Sirah Cobra Stretch dye lasers, each pumped by Continuum Surelite Nd:YAG laser

1 x Spectra Physics PDL-3 dye laser pumped by Spectron Nd:YAG laser

3 x Continuum Surelite Nd:YAG laser

1 x Lambda Physik Compex 100 excimer laser

3 x Continuum Minilite Nd:YAG laser

1 x Litron (LPU 1000) Nd:YAG laser

1 x IPG Ytterbium fibre laser

1 x 4W Shanghai Dream Laser 532 nm diode laser (SDL-F32-3000T)

Class 3B

2 x iFLEX Mustang diode laser

3 x iFLEX 2000 diode laser

1 x Uniphase (1125) helium-neon laser

1 x JDS Fibre laser

1 x Vortran Stradus 488-150  (located in MSB)

1 x Vortran Stradus 637-180  (located in MSB)

1 x Vortran Stradus 405-100  (located in MSB)

Engineering

Class 4

1 x Spectra Physics Stabilite 2017 argon ion laser

1 x Sirah Cobra Stretch dye laser pumped by Continuum Powerlite PR8000 Nd:YAG laser

2 x Litron Nano L Nd:YAG laser

1 x Pegasus PIV Nd:YAG laser

Molecular Cell Biology

Class 4

1 x Continuum Minilite Nd:YAG laser

1 x Continuum Optical Parametric Oscillator pumped by Continuum Surelite Nd:YAG laser - permanently moved to Chemistry

Class 3B

1 x Melles Griot (05LHR927) helium-neon laser

1 x Uniphase (Micro Green) Nd:YAG laser

1 x Melles Griot (35LAP431) argon ion laser

1 x Suwtech Nd:YAG laser (50 mW cw)

1 x Oz Opticts Sp3+ diode-pumped solid state laser

1 x Vortran Stradus  diode laser

Class 3R laser pointers

Metrologic

Infiniter (QPON 650)

AVS 60815

Aurora

Undefined

Undefined

Undefined

Neuroscience, Psychology and Behaviour

Class 4

1 x Coherent Enterprise 622 argon ion laser

1 x Mai Tai eHP Ti:sapphire laser

2 x Coherent Chameleon Ultra II Ti:sapphire laser

Class 3B

1 x Power Technology argon ion laser

1 x Power Technology 404 nm diode laser

1 x Shanghai Dream Lasers diode-pumped solid state laser (473 nm)

1 x Vortran Stradus 403 nm (serial number VL12159W01)

1 x Vortran Stradus 490 nm (serial number VL12159W01)

1 x Vortran Stradus 561 nm (serial number VL01161A03)

1 x Toptica iBeam Smart 488 (serial number 12355)

Physics

Class 4

1 x Continuum Minilite Q-switched Nd:YAG laser

Class 3B

1 x Melles-Griot helium-neon laser

1 x Hughes Aircraft Company 3224H-PC-51 helium-neon

1 x Hughes 3224H-PC-51 helium-neon

1 x LACOS Lasertechnik LGK 7653 laser

1 x Osram PL450B diode laser (serial number L0140550)

1 x Thorlabs L405P20 diode laser

1 x Osram PLT5 488 diode laser

Class 3A

1 x JDS Uniphase 1101P helium-neon laser

Class 3R

1 x Thorlabs CPS7805 CW diode laser

1 x Qphotonics diode laser

1 x Thorlabs CPS450 CW diode laser

1 x Thorlabs CPS520 CW diode laser

1 x Thorlabs CPS520 CW diode laser

 

Registered Laser Users

Chemistry

  • Mrs A. Al Hindawi
  • Mr A. Almohammedi
  • Ms M. Al-baqami
  • Mr Christopher Besland
  • Miss Leanne Blount
  • Mr L. Collard
  • Prof. A. M. Ellis
  • Dr C. J. Evans
  • Miss Katie Fegan
  • Mrs M. Kakaee
  • Mr Ali Nasrallah
  • Mr Marios Panagi
  • Miss Hamida Parkar
  • Mr Faizal Patel
  • Mr A. Sadoon
  • Dr S. Yang

Engineering

  • Mr P. Williams

Molecular Cell Biology

  • A. Alfi
  • Dr D. Cherny
  • Prof. I.C. Eperon

Neuroscience, Psychology and Behaviour

  • Dr T. Gerdjikov
  • Prof  N. Hartell
  • Dr V. Straub

Physics

  • Dr L. Vogel

Further Information

British Standard BS EN 60825: 1992. Radiation Safety of Laser Products, Equipment Classification, Requirements and Users Guide. British Standards Institution, Linford Wood, Milton Keynes.
Guidance on the Safe Use of Lasers in Education and Research, Association of University Radiation Protection Officers, 2006.
Guidance Note PM.19. Use of Lasers for Display Purposes. Health and Safety Executive, Baynards House, 1 Chepstow Place, Westbourne Grove, London.
These web pages are maintained by Prof A.M. Ellis, Department of Chemistry.
To make alterations or amendments please email andrew.ellis@le.ac.uk

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