The Responsible
Use of Lasers in Entertainment Venues
The following information provides a simple
introduction to the issues surrounding the installation and use
of lasers in the entertainment industry. It should be used to assist
in the risk assessment process when designing a laser display for
public viewing. Only those hazards associated with the laser beam
itself will be considered: no guidance is given on related issues
such as training, manual handling, working at heights or electrical
safety. This information is not intended to replace the existing
guidance (see further advice section).
|
Classes of laser
Lasers are usually referred to by their
class, the class of a laser is dependant on its power output
and associated hazards. The current classifications set out
in the British Standard can be simplified as follows:
| Class 1 |
Low powered, safe
for viewing under all conditions |
| Class
1M |
Low powered,
safe for viewing with the naked eye |
| Class 2 |
Low powered, normal
blink reflex should be sufficient to prevent eye damage |
| Class 2M |
Low powered, normal
blink reflex should be sufficient to prevent eye damage
when viewed with the naked eye |
| Class 3R |
Potentially harmful
to sight |
| Class 3B |
Potentially harmful
to sight (reflections may also be hazardous) |
| Class 4 |
Always hazardous to
eyes and for higher powers could cause skin-burns or pose
a fire risk if the laser beam is projected onto flammable
materials |
What risks are associated with lasers?
A laser beam is a very narrow, intense
light source that can be focussed by the eye in such a way
that the retina is exposed to a power density up to 100,000
times greater than that of the laser emitter. If this occurs,
sections of the retina can be heated by the laser energy.
This heating effect can permanently damage the retina of the
eye causing impairment of vision and in severe cases total
blindness.
|
|
Setting up the Instrument
Lasers often comprise three main parts:
a laser; a control unit (often a DMX controller or computer)
and an effects head or table. When setting up a laser it is
important to consider the following issues:
- The control unit for a laser should be positioned so that
the operator can at all times observe the display in progress.
This will allow any potential problems to be identified
quickly and the appropriate action taken.
- In the event of an emergency it should always be possible
to switch off the laser quickly. The ideal way to achieve
this is by routing the power cable through a switchbox unit.
Alternative solutions include a single switch or computer
key that will allow the power to the unit to be switched
off with a single press. The emergency cut-off (or power
supply switch) should be easily accessible and all laser
operators should be familiar with the shutdown procedure.
- It is good practise to man the control unit for a laser
display at all times when the display is in use. The operator
should be provided with adequate training to ensure they
are aware of the possible hazards associated with lasers.
- The control unit should be equipped with a security device
to prevent unauthorised people (in particular members of
the public) from interfering with the laser display. This
can be achieved using a key switch or (if a computer is
being used) a password that must be input to prevent any
settings from being changed, alternatively, isolate power
to laser equipment when not present and check for tampering
on return.
- Once in position, it is vital that the laser emitter remains
in the same place. Even a small shift in the emitter's position
could dramatically change the angle of the laser beam. The
best way to prevent this is to ensure the laser is fixed
firmly in position preferably in an area where it is unlikely
to be disturbed.
- Interlocking devices are designed to switch off the laser
in the event of mechanical component failure. When a laser
display relies on individual mechanical components, such
devices should always be present to help reduce risks from
such failure.
- Many laser displays make use of reflective surfaces such
as mirrors to produce beam sculptures and other visual effects.
Once again, a small change in the position of a reflector
can cause a huge shift in the direction of the laser beam.
As with the emitter itself, any reflectors used as part
of a display must be rigidly mounted such that they cannot
be moved accidentally or by unauthorised personnel.
|
|
Choosing a Display Area
The display area
A laser display should always take
place within a specific area. For lasers of class 2 and above,
the laser emitter should be positioned so that no member of
the audience can be exposed to hazardous laser emissions.
This can be achieved using the following guidelines:
- The laser beam or effect should
be at a height of at least three metres above floor level
in any area where a member of the public could gain access
(this includes any areas of raised seating).
Or
- The laser beam or effect should be separated by a
distance of at least two and a half metres (horizontally)
from any area where a member of the public could gain access.
A physical barrier should be used to prevent access in this
case
Special attention should be paid to
venues with balconies, camera or lighting positions or windows
leading into occupied areas as lasers projecting into these
areas may put venue personnel at risk. Special care should
be taken when planning an outdoor display. It is also important
to take into account any reflective surfaces already present
in a venue such as metal fittings, trusses, mirrors or windows
as these may have an effect on where a laser beam is directed.
Scanning the audience (class 2,
3 or 4)
Under controlled conditions it is permissible
to scan near the audience with the effects generated using
lasers. When audience scanning is desirable it is doubly important
that the laser installation is supervised by a trained operator.
The maximum power output of any class 2, 3 or 4 laser used
for audience scanning should always be approved by a professional
laser inspector before the effect is used in public. Single
laser beams should never be projected into occupied areas.
Audience scanning with the primary beam from the effects head
would rarely, if ever be acceptable.
Masking
When a laser show includes scanning
near an audience, an opaque mask (usually made of metal) can
be fitted to the edges of the laser aperture to ensure that
in the event of a component failure inside the laser, the
laser emissions cannot be project into areas other than the
display area.
|
|
Assessing the Risk
The risk assessment
The most important part of any laser
installation is the risk assessment. In many cases the use
of lasers is subject to approval from the local authority
and a well written risk assessment is often the key to this.
The aim of the risk assessment should be to assess the proposed
installation critically, looking at all the potential hazards
no matter how unlikely they may seem. This provides assurance
that even if something unexpected were to happen during a
show nobody will be exposed to potentially hazardous laser
emissions. It should always be remembered that members of
the public can be relied upon to be unpredictable (particularly
in crowded entertainment venues). This is especially true
if members of the audience might be under the influence of
alcohol or drugs (prescribed or otherwise) because not only
will their behaviour be less easy to predict, their natural
blink reflex may be impaired.
Risk assessments should always be fully
documented so they can be inspected by the operator, venue
staff and licensing authority. The following information should
be included in the risk assessment:
- The type of laser and its
power output in watts (or milliwatts)
- Details of safety devices and procedures
- The number and type of effects being used
- The display area (preferably include a diagram)
- The name and contact details of the person responsible
for the display
Specific effects
A separate risk assessment should be
performed for each type of effect used during the show although
it is not necessary to do a separate assessment for a large
number of similar effects (such as different graphics or text)
as long as the display area, power output and type of laser
emission does not vary.
For further advice and guidance consult
the following sources:
- HS(G)95 The Radiation Safety of Lasers Used for Display
Purposes
- BS EN 60825-1: 1994 incorporating Amendment Numbers 1,
2 and 3, September 2002
- Health and Safety at Work etc Act, 1974
|
Information provided on this page is the
copyright of Spectrum (UK) Lasers Limited and must not be used in
part or whole without the express written permission of Spectrum
(UK) Lasers Limited.
|
