A light beam scanning apparatus used for image recording or read-out comprises a light deflector for deflecting a light beam, an image forming lens for forming an image of the light beam on a predetermined straight line, and a long sub-scanning mirror provided moveably in the optical axis direction of...http://www.google.com/patents/US4733307?utm_source=gb-gplus-sharePatent US4733307 - Light beam recording apparatus, light beam read-out apparatus and light beam scanning apparatus
