CONCENTRIC GEOMETRIES FOR POLYGON AND GALVANOMETER SCANNING SYSTEMS
Original Publication Date: 1980-Aug-31
Included in the Prior Art Database: 2004-Apr-02
Xerox Disclosure Journal
Figures 1 and 2 show the tangential and sagittal views, respectively, of a high resolution polygon scanning system in which the axis of polygon rotation is concentric with the center of a spherical concave mirror. The incident beam 1 is reflected from a moving facet of polygon 2 which is rotating in the direction shown by arrow 6. The beam is focused on the surface of spherical concave mirror 3 and formed into a parallel deflected beam 7 by the passage through optical elements 4 and 5. Element 4 is typically a cylinder lens having power in the sagittal direction, and 5 is a group of spherical elements. Significant features of this arrangement are that the post-scanner focusing lens permits the system to achieve a flat field, and the design of the focusing lens is relatively simple. An interesting aspect of this geometry is that as the position of the tangential focusing lens is moved away from the spherical mirror, the ratio of deflection angle to polygon rotation angle continuously decreases. This offers advantages in the design of underfilled facet systems.