| 摘要 |
PURPOSE:To prevent an anamorphic lens made of plastic material from varying in performance with abmient temperature by equipping the 1st image-formation optical system with a cylindrical lens which is made of plastic material and has a negative refracting power. CONSTITUTION:Luminous flux L emitted from a light source device 1 is reflected by the reflecting surface 3a of a deflector 3 after passing through a linear image optical system 2, and the reflected luminous flux L is deflected according to the turning of the deflector to form an image of a medium 5 to be scanned through the anamorphic lens 4 having a toric surface. The anamorphic lens 4 is made of the plastic material and shifts in its image formation position in a plane of deflection according to temperature, but the variation is canceled by the 1st cylindrical lens 2a which is made of the plastic material and has the negative refracting power, thereby maintaining the image formation position near the medium 5 to be scanned. |
