| 摘要 |
<p>In a light beam scanning system, a beam shaper shapes light beam emitted from a light source. The shaped light beam is deflected by a deflector to scan a surface in a main scanning direction. A scanning/imaging optical system causes the light beam deflected by the deflector to form an image on the surface and scan the same. The beam shaper includes a diverging optical system which converts the light beam into divergent light. The scanning/imaging optical system consists of first and second lens elements arranged in this order from the light source side and having first to fourth surfaces as numbered from the light source side and satisfies formulae, <MATH> <MATH> <MATH> <MATH> wherein fall, fGF, r1GR, r2GR, r4GR, fGR1 and fGR2 respectively represent the composite focal length of the beam shaper and the scanning/imaging optical system, the focal length of the beam shaper, the radius of curvature of the first surface of the scanning/imaging optical system, the radius of curvature of the second surface of the scanning/imaging optical system, the radius of curvature of the fourth surface of the scanning/imaging optical system, the focal length of the first lens element and the focal length of the second lens element. <IMAGE> <IMAGE></p> |
