A mechanical galvanometer tilt control system includes two beam detection sensors that detect vertical displacement caused by the horizontal rotation of a galvanometer and the vertical rotation of a photoconductive drum. The galvanometer may be in communication with a mirror holder that holds a mirror....http://www.google.com.hk/patents/US7943896?utm_source=gb-gplus-share專利 US7943896 - Mechanical galvanometer tilt correction control
