Polygon scanner having a fluid film bearing and active correction of cross-scan and in-scan errors

摘要

Polygon scanner optic 54 is rotated by motor 52 having a fluid film bearing, preferably a self-acting gas bearing 88; all contained within a windowed enclosure (U, Fig 3) to prevent air turbulence effects. Repeating cross-scan error components are mapped by system 300 and actively corrected using a piezoelectric actuator 60 to directly displace the laser source 62 or optionally, not shown, using a mirror in the optical path that is tilted by means of an electro-optic device to displace the laser beam. The repeating components of in-scan errors are similarly and independently mapped and corrected by summing with the output of a phase detector 110 in a line scan speed control system 100. A method for calibration of the cross-scan error map established at the factory may be implemented by a self-calibration sub-routine using a stored sinusoidal voltage waveform 312.