Patent ID: 6980342

Claim:
An optical beam scanning device comprising: a pre-deflection optical system for adjusting a light beam emitted from light source means so as to be focused as a line image longitudinally extending in a direction corresponding to a main scanning direction; optical scanning means having a plurality of reflection surfaces, the light beam being reflected by each of the plurality of reflection surfaces so as to scan an object to be scanned; and an imaging optical system having one or a plurality of lenses for focusing the light beam scanned by the optical scanning means on the object to be scanned, wherein the imaging optical system comprises a lens satisfying Lc/Le≧2.2, where a light passage distance through the inside of the lens when the light beam scans the center of an image region is denoted as Lc and a light passage distance through the inside of the lens when scanning the end of the image region is denoted as Le.