| 摘要 |
<p>A multi-beam exposer unit 1 includes <IMAGE> half mirror 11 for synthesizing <IMAGE> light to M groups of light beams, M sets of optical members (12), having positive power with a large absolute value as compared with a case of a main scanning direction, for further converging the beam in a sub-scanning direction, a synthesizing reflection mirror (13) for reflecting M groups of beams to be substantially overlaid on each other in a first direction, a polygon mirror unit (5) for deflecting M groups of beams, and a dust prevention glass (14) inclined to a direction opposite to a direction where the half mirror is inclined, thereby reducing influence of coma aberration exerted on M groups of beams by the half mirror. <IMAGE></p> |
