Oh dear, clichés galore coming up. Anyway, to answer SLR Dave, yes i did mean fast 'deflection' of light from the moving mirror surface. Think of a projector with a fixed body, a strong lamp shining out the lens at the front, with a variety of shapes and colours placed in the light beam path. Now put a mirror in front of the projector and move it around. Thats how you get the club lighting effect with 'scanners'. See pic below

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