| 摘要 |
PROBLEM TO BE SOLVED: To provide a small-sized scanning optical system which is constituted by combining a deflecting mirror and a reflection optical system so that an incident beam and the center beam of scanning beams may be approximately rectilinear or parallel. SOLUTION: The scanning optical system is comprised of an incidence-side reflection optical system 10 on which a light beam from a light source 1 is made incident, a deflecting mirror 3 which reflects and deflects the light beam emitted from the incidence-side reflection optical system 10, and an exit-side reflection optical system 20 on which the light beam reflected by the deflecting mirror 3 is made incident, and a revolving shaft 4 of the deflecting mirror 3 is made approximately parallel with principal rays 2 on the axis, which are made incident on the incidence-side reflection optical system 10 from the light source, when principal rays 2 on the axis are defined as rays which are emitted from the light source 1 and pass the center of the deflecting mirror 3 constituting a stop of the optical system. |
