A laser lighting display or laser light show involves the use of laser light to entertain an audience. A laser light show may consist only of projected laser beams set to music, or may accompany another form of entertainment, typically musical performances.
Laser light is useful in entertainment because the coherent nature of laser light allows a narrow beam to be produced, which allows the use of optical scanning to draw patterns or images on walls, ceilings or other surfaces including theatrical smoke and fog without refocusing for the differences in distance, as is common with video projection. This inherently more focused beam is also extremely visible, and is often used as an effect. Sometimes the beams are "bounced" to different positions with mirrors to create laser sculptures.
Laser scanners consist of small mirrors which are mounted on galvanometers to which a control voltage is applied. The beam is deflected a certain amount which correlates to the amount of voltage applied to the galvanometer scanner. Two galvanometer scanners can enable X-Y control voltages to aim the beam to any point on a square or rectangular raster. This enables the laser lighting designer to create patterns such as Lissajous figures (such as are often displayed on oscilloscopes); other methods of creating images through the use of galvanometer scanners and X-Y control voltages can generate letters, shapes, and even complicated and intricate images. (The use of X-Y raster scanning to create images is also used in television picture tubes.) A planar or conical moving beam aimed through atmospheric smoke or fog can display a plane or cone of light known as a "laser tunnel" effect.
Classification of light show effects
Laser effects for displays and light shows can be divided into two main categories; beam effects and screen effects.
Beam effects are the effects created by the laser beam itself traveling through the air towards or over the viewers. Beam effects include:
Static beams: These are beams that do not move but are switched on and off (with and without bounce mirrors). Static beams are typically generated from a beam table. Static beams can be the most dangerous type of laser effects and must be separated from the audience to prevent contact with the viewers.
Dynamic(scanned) beam effects: These are beams that move rather than just turning on and off. Dynamic beam effects are generated by X-Y scanning systems and include fans of beams, beam sequences, sheets of light, cones and tunnels of beams and some moving diffraction grating effects.
Screen effects are projected laser effects that require a screen (or other surface) to make them visible. They can be projected onto screens, planetarium domes, walls, buildings, billboards, the sides of mountains and even (under optimum conditions) clouds.
Examples of screen effects include graphics and animations, cycloids, abstracts, lumia, diffraction gratings and other projected optical effects.
Laser display sub-systems
There are six major sub-systems in a laser light show;
- Laser and exciter (laser power supply);
- Laser projector (containing colour control, beam table and scanning sub-systems);
- Control console;
- Laser Graphics system;
- Outboard equipment.
In addition there may be additional equipment such as screens or scrims, power distribution systems, scaffolding and water pumps.