Provided are a multi-beam scanning optical system capable of implementing high-quality printing in relatively simple structure and at high speed, and an image forming apparatus using it. The multi-beam scanning optical system has an incidence optical unit for guiding a plurality of beams emitted from...http://www.google.com.au/patents/US6476955?utm_source=gb-gplus-sharePatent US6476955 - Multi-beam scanning optical system and image forming apparatus using it
