Scanning projection optical device

A scanning projection optical device, which projects an object by scanning with a predetermined scanning width, comprising:

• an illuminator for illuminating the object upon an arc-shaped region,
• a catadioptric system for forming on an image plane an image of the object illuminated on the am-shaped region by the illuminator,
• a photosensitive member located in the image plane, and
• a driving device for relatively moving the object and the photosensitive member relative to both the illuminator and the catadioptric system in the direction perpendicular to the direction of the illumination,
• wherein said catadioptric system is an optical system telecentric in both object-and image-field sections, and has a first, positive power lens-system, a second, substantially non-power lens-system, and a concave mirror;
• said first, positive power lens-system and said concave mirror cooperatively satisfy a Petzval condition to correct field curvature;
• and
• without impairing the Petzval condition satisfied by the first lens-system and the concave mirror, said second lens-system corrects aberration of the arc-shaped region centering around the optical axis.