I have a Samsung laser printer with a perpetual paper pick up problem so decided to take it to bits to investigate. It is a pleasingly simple module, pictures now follow.
The other side
At the bottom left we have the spinning mirror, at the top is the weird looking lens that corrects for the variation in distance from the mirror to the drum in the printer, probably does some focussing too, not sure.
This is a brushless motor controller by Rohm especially designed for polygon scanners. The control is very simple from what I have managed to work out, there is a clock to set the speed, a start/stop input and an output to say then the PLL has a lock (i.e. the speed is constant). Then power which is 24v (up to 36 but I suspect 24).
The optics consist of a collimator, a metal aperture and then a focussing lens with a long focal length. The mirror is very thin so perhaps the aperture stops stray reflections from other parts of the motor.