A method and apparatus for enhancing the accuracy of scanner systems

摘要

An apparatus for use in improving the accuracy of optical systems such as internal drum photoplotters includes a raster scanner responsive to control signals for advancing relative to a substrate an optical beam across a substrate surface in a first direction forming a scan line and for cooperatively advancing relative to the substrate the optical beam in a second direction substantially perpendicular to the first direction. A signal generator provides a clock signal configured to control the advancement of the optical beam in a first direction. There is a memory for storing error signals indicative of deviations of the curved surface from a preferred value of curvature. The apparatus is characterized by a controller for generating control signals in dependence on the error signals such that the phase of the clock signal is adjusted, thereby removing the curvature error for a segment of the scan line.