Light-beam scanning apparatus having two beam waists

摘要

A light beam scanning apparatus including a light source for emitting a light beam and a rotatable polygon mirror having at least one surface for reflecting the light beam to a second surface being scanned. A flat field lens is provided between the polygon mirror and the second surface and an optical system is provided close to the second surface. The optical system has a light converging effect only in the vertical direction perpendicular to the scanning direction, and the light beam forms a first beam waist between the flat field lens and the optical system, and a second beam waist substantially on the second surface.