Multispot polygon ros with maximized line separation depth of focus

摘要

An apparatus for improving the depth of focus in a raster output scanner (ROS), and more particularly to a system for maximizing the line separation depth of focus of a multispot ROS while maintaining the system common depth of focus. The apparatus comprises: a source of at least two light beams (A,B; Fig. 1); a scanning polygon mirror having at least one facet (92); pre-scanning optics including a collimator (84), an aperture (86) and a cross-scan cylinder lens (88); and post-scanning optics including a dual element (94a,94b) f-theta scan lens (94) and a wobble correcting element. In a preferred design for a ROS-based system, the system common depth of focus (system common DOF) is maximized, where the system common DOF is characterized as the depth-of-focus over which all performance parameters are met. The optical system design achieves a desirable system common DOF while maintaining a line separation of 127 mu m (1/200 inch).