The power required to produce an effective beam display is directly related to the size of the venue, the ability to fog the venue, the ambient light level, and the viewing angle. If the last three factors can be optimized, you can get by with a lower powered, less expensive laser. If you are unsure about any of these factors, however, get the largest laser that your budget will allow. The simplest effect is the straight beam, in which a static beam emanates from the projector. The beam can target single or multiple mirrors to create a sequence of patterns.
Straight beams can also target remote devices that add interest to the show.
One of these devices is called a reflective diffraction grating. It reflects a beam like a mirror while also breaking up the single beam into multiple shafts of light. The grating also acts like a prism and spreads apart the colors of the output beams. One of the more popular effects is the Machida grating, which projects a 180-degree fan of beams from just one point. Other, more complex remote devices that straight beams can target are motorized effects.