Compact high resolution high speed symmetrical scanning optics using multiple deflections

摘要

To remove the limitation imposed on the number of facets in rotating polygon scanners and to improve the scanning capabilities of vibrational rotating mirrors, a fixed mirror is positioned in front of a deflecting facet to implement successive deflections by the same deflecting facet. In the multiple deflection system thus formed, the deflecting facet width is used very efficiently by directing the input beam with tangential symmetry and oblique to the tangential plane, so that the said beam enters from one tangential side of the mirrors and emerges from the opposite side after a specific number of reflections and deflections between the two mirrors, irrespective of the angular position of the deflecting facet. There are also imaging optics to focus an essentially collimated input light beam to a tangential line image, direct the beam toward the multiple deflecting system, recollimate the output deflected beam and focus it to a circular spot on an image plane. By proper configuration of the beam, the major part of the sagittal scan spot displacement is eliminated in a self correcting mode during the multiple deflection process. The imaging optics, at the same time, corrects the remaining part of the displacement, so that relaxed tolerances on the deflecting facet errors are possible.