[frabert]

You could use three lasers (rgb) and merge their beams using a set of dichroic mirrors, then use the resulting beam as if it was your red laser. The control logic then switches the three lasers instead of only one.

[squarefoot]

This, and then projecting the RGB beam from the rotating mirror fixed on the ceiling to a circular screen surrounding the user for full 360 degrees experience.

[MarkSummer]

...or what frabert said much more succinctly :)

[Vrpe]

Both are good :)