| 摘要 |
PURPOSE:To make an irregularity in pitch which is caused periodically on a scanning surface inconspicuous by providing a means which deflects finely a light beam in a subscanning direction at random on an optical path extending from a light source to a scanning surface through a rotary polygon mirror. CONSTITUTION:The light beam 2 from the beam light source 1 passes through an acoustooptic deflector 3 and is reflected by the rotary polygon mirror 4 to make a main scan on the scanning surface 6 as shown by an arrow B after passing through a scanning lens 5. If a reflecting surface 4a of the polygon mirror 4 tilts, scanning lines on the scanning surface have a periodically irregu larity in pitch. The light beam is deflected finely in the subscanning direction through the deflector 3 after impinging on the polygon mirror, so the periodical irregularity in pitch on the scanning surface can be made inconspicuous. |
