| 摘要 |
PURPOSE:To correct the plane tilt error of a rotary polygon mirror with simple device constitution and to improve the drawing quality and read accuracy by using a scanning lens which has a scanning characteristic f.sintheta and making a light beam incident on the angled planes of the rotary polygon mirror from right below the optical axis of the scanning lens. CONSTITUTION:A sintheta lens 10 is used as the scanning lens which guides a light beam reflected by the polygon mirror 9 to the exposed of a photosensitive material 12. The light beam from a laser light source 2 is made incident on the respective mirror surfaces of the polygon mirror 9 from almost right below the optical axis of the f.sintheta lens 10, i.e. right below the optical axis of the f.sintheta lens 10 in the plane containing the optical axis of the F.sintheta lens 10 and the axis of rotation of the polygon mirror 9 which crosses it at right angles, and the angle of incident of the light beam on the polygon mirror 9 is finely adjusted. Consequently, the plane tilt error of the respective mirror planes of the polygon mirror 9 is corrected with the simple constitution. |
