I was just wondering how an optical mouse worked. Why is it so much more precise then my wheel mouse, and why does it seem to go so much smoother?
It images the mousing surface multiple times a second, tracking the changes. Thus the mouse movement is inferred and translated into cursor movement on screen.
The reason they are more accurate than ball mice is because the balls can jiggle and get stuck a bit on the rollers (especially if the ball is dirty) and so forth. The lack of moving parts makes measuring the distance moused more precise.