Patent ID: 6195189
Filing Date: 2001-02-27
Classification: G02B

Abstract:
A light beam scanning system comprising:a beam shaper means which shapes a light beam emitted from a light source, wherein the beam shaper means comprises a diverging optical system which converts the light beam into divergent light;a deflector means which deflects the light beam to scan a surface in a main scanning direction; anda scanning/imaging optical system which causes the light beam deflected by the deflector to form an image on the surface and scan the surface;wherein the light beam entering the scanning/imaging optical system is the divergent light converted by the diverging optical system;wherein the scanning/imaging optical system consists of, in an order from the light source side, a first lens element and a second lens element, wherein the scanning/imaging optical system has first to fourth surfaces as numbered from the light source side and satisfies the following formulae (1) to (3):-1.42<f.sub.all /f.sub.GF <0 (1)r.sub.1GR <0, r.sub.2GR <0, r.sub.4GR <0 (2)f.sub.GR1 >0, f.sub.GR2 >0 (3)wherein f.sub.all represents the composite focal length of the beam shaper means and the scanning/imaging optical system, f.sub.GF represents the focal length of the beam shaper means, r.sub.1GR represents the radius of curvature of the first surface of the scanning/imaging optical system, r.sub.2GR represents the radius of curvature of the second surface of the scanning/imaging optical system, r.sub.4GR represents the radius of curvature of the fourth surface of the scanning/imaging optical system, f.sub.GR1 represents the focal length of the first lens element and f.sub.GR2 represents the focal length of the second lens element.