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
SOME OF THE LASER TYPES
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
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.
HOW A LASER WORKS
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.
The mirror can be moved by one of two standard methods:
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.
I reproduce (with permission) parts of the safety guidance leaflet below:
Controlling the radiation safety of display laser installations
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?
Are all laser beams that are accessible by people safe to view?
What action do you need to take?
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 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
co-operate with the installer so that they can complete the laser show safely.
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