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.
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