Vol. 16, No. 3, Oct-December 2005 

Show Basics: Glossary of Laser Display Terms
By David Lytle, Editor, The Laserist

Laser Displays Terminology: The Essentials

Audience Scanning: This is the top of the pyramid when it comes to laser effects-pointing the beam directly at the audience and letting the effects wash over them. Who doesn't like being enveloped by a cone of laser light? International safety standards have been developed to determine the proper power levels for safe audience scanning (avoiding eye injuries is the concern), and the effect is extremely popular in Europe. In the more litigious United States, audience scanning is not seen at all, even though it could be done if a company were willing to jump through the legal and bureaucratic hoops.

Beam Effects: As opposed to laser graphics projected on to a screen, beam effects use the beam itself as an sculptural element in space. Scanned bean effects include tunnels, cones and fans of light that float in the air. Static beams are typically bounced off mirrors to create spider webs of light and can also be cycled through chase sequences.

CDRH (Center for Devices and Radiological Health): A division of the U.S. Food and Drug Administration that regulates laser display products and displays.

Graphics: As opposed to beam effects that are seen in the open-air, laser graphics are projected on to surfaces. Graphics can be representational (text, logos) or abstract.

Galvo, galvanometer: The galvo is the motor that moves the mirror that scans the laser beam to create laser graphics and beam effects. Galvos usually come in a set of two, with one scanning the beam horizontally (X-axis) and the other vertically (Y-axis).

Head: The laser tube (enclosed in a case), as opposed to the laser power supply, which is often packaged separately. Head also can refer to a set of X-Y scanners, as in a scan head. A single projector will often use fiber optic cables to feed light to multiple scan heads positioned on a stage.

ILDA: The International Laser Display Association represents laser light artists and businesses. It develops technical standards (such as the ILDA Standard Projector format for promoting compatibility in laser projector systems), represents the industry on safety and regulatory issues, and holds an annual awards competition for artistic and technical achievements.

Laserist: Someone who performs or designs a laser show. Also the title of ILDA's quarterly magazine (The Laserist) and this Web site.

Lumia: An abstract laser graphic effect produced by shining the laser through a distorting medium, such as rippled glass. These cloud-like, wispy images can be hypnotic to watch.

Mirror Table: Typically consists of a number of small mirrors on precision mounts that are used to create a static array of beam effects that can by cycled through a chase sequence. Actuator arms are used to direct the beam to individual mirrors.

PCAOM (polychromatic acousto-optic modulator): An extremely fast, electronically controlled crystal used to mix the colors in a white-light laser beam. The PCAOM can simultaneously mix a number of colors in a single beam to produce the desired final color.

Scanner: This usually refers to a galvo, but can be any device that moves the laser beam back and forth.

Variance: All U.S. shows that use moderate- or high-power lasers must have a variance granted by the CDRH that allows the show to take place. CDRH's regulations cover laser equipment and laser effects, and variances must usually be obtained for each venue where a show is performed.

White-light laser: A laser that produces a single beam containing a number of different colors. If the white-light beam were to pass through a prism, it would be separated into several beams with a distinct colors. Ideally, the white-light laser would have the proper balance of red, green and blue needed to a make full-color display. In contrast, some lasers produce only one or two colors, and need to be combined with additional lasers to create a full-color system.

YAG: A solid-state laser that uses yttrium aluminum garnet as the lasing medium. In practice, the term is widely used to refer to any solid-state laser that produces a bright-green beam, even if the lasing medium is not YAG. Most of these lasers use a flashlamp or laser diode to excite, or "pump" the lasing medium.