A raster scanning system is disclosed which utilizes a focus error correction system and a pre-polygon cross-scan cylindrical lens for correcting focus error both in the fast-scan plane and in the cross-scan plane without affecting the scan characteristics of the post polygon optics. The focus error...http://www.google.com/patents/US5257125?utm_source=gb-gplus-sharePatent US5257125 - Afocal optical system for focus error correction in laser scanning systems
