| 摘要 |
PURPOSE:To simplify the adjustment of an optical axis and to miniaturize an optical system by arranging light emission means which radiate plural light beams close to one another on the same plane in parallel with a scanning line so that they radiate the respective light beams nearly on the same point on the reflecting surface of a polygon mirror. CONSTITUTION:The light beams projected from semiconductor lasers LD1, LD2 and LD3 corresponding to red, green and blue pass through corresponding collimator lenses 211-213, pass through a cylindrical lens 220 and are focused on a certain point on the polygon mirror 230. The light beams are reflected with respective reflection angles in regard to angles of incidence on the reflecting surface of the polygon mirror 230 and pass through an ftheta lens 240, then they are reflected by the cylindrical mirror 250 to expose on a photosensitive material S. Thus, the polygon mirror can be made as small as necessary and a device can be miniaturized. Moreover, the adjustment of the optical axis can be easily executed since the constitution is simple. |
