Cluster laser stage lighting I'm not entirely sure if this is on-topic here, since it's about stage lighting rather than audio or video directly, but I'll give it a shot.

I've been looking at various types of laser stage lighting, and I'm trying to work out how they work internally. I figure the scanning lasers (single fast-moving beam) work by firing a single laser onto a rotating mirror, or a mirror controlled by servos for more precise movements.

However, I can't figure out how the cluster lasers work. I'd guess there's some kind of prism in there, or some trickery with a set of mirrors and lenses that somehow "split" the beam, but I can't quite figure it out. My first thought was a fixed prism, but that wouldn't explain how these devices can spread, focus and rotate the beams.

How do these laser effects usually work?
The way most stage laser effects work is by using a holographic plate or diffraction grating which splits the single beam up into multiple beams. 

[image removed due to a DMCA request from copyright holder]

These then pass to further holographic elements to provide shapes and lines, and these can then be manipulated further with lenses or mirrors.