Lasers in the theatre

Illuminati Creative Technology, Colchester UK

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WHAT IS A LASER AND HOW CAN I USE ONE IN THE THEATRE OR IN THE VISUAL ARTS? It is a bright torch, with a nice tight beam ok? Thats all it is. I dont recommend you to read your script by it in the dark, but apart from that you can create a wide variety of effects by waving the beam about and switching it on and off. Colours? Well mostly you are stuck with the native colour of the type of laser you are using, mostly green or red, but there are types which give a white light which can be spit into colours. Effects fall into two basic types: beam effects and image projection effects. For beam effects, although you will generally see a beam in most indoor and outdoor situations, fog or haze is a must if you want the full spectacle. For image effects, dont use the haze or the image will be a bit confused and fuzzy.

Some tricks with lasers:

1) use the GAPCI technique (It stands for "Get A Professional Company In" ) Why? They mostly know what they are doing and can indemnify you against million-pound law suits where you blind an audience menber)

2) er, thats it.

Having said that, here are a few things you can ask a laser company to do

Scan a mirror ball with a laser. This gives a most beautiful and safe effect. However, you must be absolutely certain that the mirror ball does not stop revolving or that the beam stops scanning over the entire laser-facing area of the mirror ball or it becomes dangerous as the beam can be reflected out of control. There are safety interlocked mirror balls of various sizes available, but not all laser companies use them, preferring the dead man's handle approach.
Great alien skyscape effects can be made with rapidly scanned white, green or blue laser backlights creating as far as possible a complete ceiling sheet of laser light in conjunction with still or lazily moving fog. Haze is good too, but I prefer the larger clumps produced with glycol fog.
A bladerunner style can be produced in a similar way with blue or red lasers and haze. The laser beams can be split into multiple beams with optical beamsplitters and used to create grids and outlines
If you want to use a laser to project words or numbers, this is possible, but the smaller the image size the better the image and the less flicker you will get.
You should able to make a star Wars phaser gun effect using a small laser pointer or a 10mw laser diode fitted with a microswitch triggerwhich can be used with reasonable safety in a hazed room.


Air-cooled lasers up to 200mw

Green or red

Air and water cooled lasers up to 2 watts

Green/blue or full colour

Medium frame water cooled lasers up to 4 watts

Green/blue or full colours

Large frame water-cooled lasers 15 watts plus

Green/blue, red (5-7watts) or full colour

For more information click here  

Tech Stuff:

What is a laser and how does it differ from other light sources?

A laser emits Coherent light. this is a form of light, the constituent wave trains of which are emitted by a single source and move in unison. The LASER is the main source of such light.The output from a laser can be collimated into a tight beam which is very intense and highly controllable.

In ordinary thermal light sources various portions of the heated filament emit light in random small bursts that lack the synchronization needed for coherent light. The light is out of phase with itself and has a great deal of scatter

A laser is useful because it produces light that is not only of essentially a single frequency but also coherent, with the light waves all moving along together in unison.

Light moves in the form of a wave, with crests and troughs.  Like all other kinds of electromagnetic radiation, it can be characterized both by its frequency, or number of wave crests passing a given point per second, and by its wavelength, or distance between wave crests. Different wavelengths of light are seen as different colors.

The smallest unit of light is the PHOTON, which may be thought of as a particle as well as a wave.  In beams of light from ordinary natural or artificial sources, these individual photon waves are not moving along together because they are not being emitted at precisely the same instant but instead in random short bursts.  This is true even when the light is of a single frequency.  Such beams are called incoherent. 


In its simplest form a laser is simply a tube with a mirror at each end called a Brewster Window. For a ruby laser, a crystal of ruby is formed into the cylinder. A fully reflecting mirror is placed on one end and a partially reflecting mirror on the other. A high-intensity lamp is spiraled around the ruby cylinder to provide a flash of white light that triggers the laser action. The mirrors reflect some of this light back and forth inside the ruby crystal, stimulating other excited chromium atoms to produce more red light, until the light pulse builds up to high power and escapes through the partially reflecting mirror. The pulse of light lasts for only about 300 millionths of a second-but very intense. Early lasers could produce peak powers of some ten thousand watts. Modern lasers can produce pulses that are billions of times more powerful.

In the last analysis a laser is merely a giant but quite bright torch. Any effect that it is capable of producing is merely the effect produced by waving it about, and flashing it on and off.
It is obviously not particularly practical to wave the whole laser, nor is it particularly convenient to switch it on and off at high speed. In practice we wave a smaller and very much lighter mirror in the path of the beam together with a chopper or shutter.

The mirror can be moved by one of two standard methods:
1) By attaching it to  the needle of a sensitive galvanometer or volt meter and varying the voltage applied: or
2) by attaching it to a pair of Stepper Motors  which respond to a digital signal from a computer.

The beam is emitted from the laser and typically passes through one or  more beamsplitters and effects heads. Each effects head can be operated independently: One may be producing flat-sheet scanning effects while another is making tunnel effects etc.

Very low power laser equipment, such as those used in CD players, laser pointers, etc., have virtually no safety implications. However,  all Class 2B or above laser equipment used in the entertainment industry has to conform with stringent safety regulations published by the H +SE.

I reproduce (with permission) parts of the safety guidance leaflet below:

Controlling the radiation safety of display laser installations
Most lasers that are used in entertainment, theatre and public exhibition work emit beams that are bright enough to cause a significant eye injury risk. High power lasers with radiant powers that exceed around 0.5 watts may also cause skin burns.

This leaflet provides employers and employees who use lasers in these activities and companies that manufacture or supply such equipment with general information on the laser radiation safety problems they need to consider. For a more detailed guide on the safety of display laser installations see HSE guidance publication HS(G)95 The radiation safety of lasers used for display purposes.

What are the key safety problems?
The most important issues are those of laser beam viewing safety assessment and restriction of access to beams that are identified as hazardous. These are the main questions to be answered:

Are all laser beams that are accessible by people safe to view?
You need to think about this both in relation to normal equipment operation and fault conditions. In particular, the following situations need to be considered:deliberate audience scanning;alignment and setting up; and beam projection at roadways, occupied buildings and into aviation airspace.

Can hazardous beams be kept inaccessible in all conditions of equipment operation?
You need to think about:engineered features such as beam enclosure, masking and stops;
administrative controls such as barriers, signs, key control of equipment and staff training.

Has the need for eye protection been considered?
People who may be exposed to hazardous beams (especially during alignment and setting up procedures) need to be provided with suitable protective eyewear.

What action do you need to take?
If you are a manufacturer, designer, importer, supplier or installer of display laser equipment or of components for such equipment, you have a duty under the Health and Safety at Work etc Act 1974 to consider the safety of your products when they are used by a person at work.

In particular, you must:

so far as reasonably practicable, ensure that your products are designed and constructed so that hazardous beams are inaccessible to people (especially audiences). This applies both during normal operation and following any reasonably foreseeable fault in the product's operation; and
if access to a hazardous emission is necessary during installation and setting up of your products, provide the purchasing employer with safety information, eg on the training, safe systems of work and any personal protective equipment that will be needed.
The current British Standard on the safety of laser products gives useful information on safe equipment design

If you are an employer who uses display laser equipment either at your own premises or under contract to a venue operator, you must:

.assess the health and safety risks caused by your work; including risks to employees and the public (especially audiences), and ensure that these risks are controlled so far as is reasonably practicable; and
.ensure that the work equipment you provide is suitable "in any respect which will affect the health and safety of any person"1. The current British Standard on the safety of laser products gives useful information on safe equipment design and lists the personal laser radiation exposure limits .

If you are a venue owner who lets contracts for laser shows to be provided at your premises, you have a duty to:

co-operate with the installer so that they can complete the laser show safely.
It is good practice for venue owners to make sure that the installer has adequately assessed the safety of the laser show at their premises and has addressed the issues dealt with in this leaflet.

Further Information
Work Equipment. Provision and Use of Work Equipment Regulations 1992. Guidance on regulations L22 HSE Books 1992 ISBN 0 7176 04144.
Management of Health and Safety at Work. Management of Health and Safety at Work Regulations 1992 Approved code of practice L21 HSE Books 1992 ISBN 0 7176 0412 8
Personal Protective Equipment at Work Regulations 1992. Guidance on regulations L25 HSE Books 1992 ISBN 0 7176 0415 2
Health and Safety at Work etc Act 1974 HMSO 1974 ISBN 0 1054 3774 3
5 Steps to risk assessment 1994 HSE Books IND(G)163L
Safety of laser products. Part 1. Equipment classification, requirements and user's guide British Standard BS EN 60825-1:1994 ISBN 0 580 23532 7 Contact BSI for latest revision
The radiation safety of display laser installations HS(G)95 HSE Books 1996 ISBN 0 7176 0691
Lasers, Festival and Entertainment Lighting Code The Institution of Lighting Engineers 1995
Safety of laser products. Part 3. Guidance for laser displays and shows. IEC 825 - 3 1995
HSE priced and free publications are available by mail order from:

HSE Books, PO Box 1999, Sudbury, Suffolk CO 10 6FS. Tel: 01787 881165 Fax: 01787 313995

HSE priced publications are also available from good booksellers.

For other enquiries ring HSE's InfoLine Tel: 0845 345 0055 , or write to HSE's Information Centre. Broad Lane, Sheffield S3 7HQ.

This guidance is issued by the Health and Safety Executive. Following the guidance is not complusory and you are free to take other action. But if you do follow the guidance you will normally be doing enough to comply with the law. Health and safety inspectors seek to secure compliance with the law and may refer to this guidance as illustrating good practice.

This publication may be freely reproduced, except for advertising, endorsement or commercial purposes. The information is current at 9/96. Please acknowledge the source as HSE.

IND(G)224L 10/96 C50