70 Part 2 · Entertainment Discipline Overview Laser systems provide spectacular effects for a wide variety of productions, from big-budget corporate spectaculars to concerts. The basic concept behind a laser light show is very simple: Using one or more colored, very narrow beams of light (provided by one or more lasers), a pattern or graphical picture is drawn very rapidly--so fast, in fact, that it's hard for the eye to see the laser dot as it draws the picture or atmospheric effect. These effects typically have been provided as a service by laser companies, and, traditionally, these supply companies custom- build or modify their own systems. L ASER S YSTEM C ONTROL E QUIPMENT Laser systems generally break down into series of standard components. First, of course, there are the laser light sources, which produce powerful, collimated beams. Modern lasers for light shows can be either a set of gas or solid state lasers producing individual colors or a "white" laser, which produces multiple colors simultaneously. Next in the optical chain is typically a color-splitting and blanking device, which acts as a sort of remote-controlled electric prism. This device (which, as of this writ- ing, is often replaced by the use of solid- state diode pumped lasers) is called a polychromatic acousto-optic modulator (PCAOM) (in the photo, the PCAOM is at the upper right, and connected using a BNC connector), and allows only a certain color to pass at any given instant, with all the remaining light sent out as a "waste" beam. These devices work at blindingly fast speeds, allowing the subsequent com- ponents of the laser system to deal only Courtesy Pangolin Laser Systems with a particular color at any given frac- tion of a second. The last part of a typical laser projector "scans" the beam, typically using two "scanners," 1 one for the X axis and one for the Y. So far, we've only talked about hardware, but also a crucial part of a laser system is, of course, the software, which takes a graphic image from the mind of the designer and turns it into raw 1. Historically, these high-speed, closed loop optical servos were inaccurately referred to as ""galvanometers."