Resonant galvanometer scanner system employing precision linear pixel

Abstract

A high resolution scanning system, employing non-linearly driven galvanometer deflection optics, compensates for both the non-linear rate of travel of the information pixel beam and for pixel position offset introduced by an optical subsystem (a flat field lens) that equalize pixel size and quality across the recording medium. The system employs a single high speed reference clock the output pulses of which are counted and used to address a compensation data-containing PROM (programmable read only memory). The contents of successive addresses of the PROM contain pixel location codes identifying the position on the recording medium where a pixel of interest is to be recorded. These codes are derived in accordance with the periodic non-linear rate of travel of the scanning optics across the recording medium and the measured parameters of a flat field lens disposed in the path of the scanning beam. For a sinusoidal scan, the successive PROM addresses contain pixel location defining codes that are effectively compensate for the non-linearity of the sinusoidal scan rate of the galvanometer deflection drive and the image position offset introduced by the flat field lens optical subsystem. Because of this complementary action, the spacing between pixels can be made constant along a recorded line of pixel data.