Patent ID: 7497578

Claim:
An arrangement for monitoring motion of a scan mirror, comprising: a) a drive, including a permanent magnet having a permanent magnetic field and mounted on the mirror for joint movement therewith, and an energizable drive coil which, when energized by a periodic drive signal, generates an electromagnetic field that interacts with the permanent field of the magnet to jointly move the mirror and the magnet; b) a primary feedback coil in proximity with the magnet for generating a primary feedback signal indicative of joint motion of the mirror and the magnet, the primary feedback coil also being in proximity with the drive coil and being contaminated by crosstalk with the drive signal; c) a secondary feedback coil positioned further away from the magnet as compared to the primary feedback coil, and operative for generating a secondary feedback signal weaker than the primary feedback signal and also indicative of joint motion of the mirror and the magnet, the secondary feedback coil also being in proximity with the drive coil and also being contaminated by the crosstalk with the drive signal; and d) means for processing the feedback signals to remove the crosstalk from the primary feedback signal to thereby produce a crosstalk-reduced feedback signal indicative of the motion of the scan mirror.