摘要 |
In an optical system, the scanning center axis of a scanning lens, the principal ray of a laser beam applied to the scanning lens, and the rotational axis of a polygon mirror are in one plane. By forming a thin film layer on the deflecting facets, the exposure quantity of a photo conductor, which decreases as the incident angle to the deflecting facet increases, is corrected. The thin film layer has the increasing ratio of the reflectance that increases as the incident angle, which principal ray of the laser beam forms with the normal line to the deflecting facet of the polygon mirror, increases.
|