Patent ID: 7550712

Claim:
An optical scanning system, comprising: light source means; deflecting means; an input optical system for directing a light beam from said light source means to said deflecting means; and an imaging optical system for directing the light beam deflected by said deflecting means onto a surface to be scanned; wherein the light beam incident on a deflecting surface of said deflecting means has a width larger than that of said deflecting surface with respect to a main-scan direction, wherein a light-entrance side F number of said input optical system in the main-scan direction is larger than a light-entrance side F number of said input optical system in a sub-scan direction, wherein said input optical system includes a first optical element having a power both in a main-scan sectional plane and in a sub-scan sectional plane, and a second optical element having a power in the sub-scan sectional plane, wherein said first optical element is made of a plastic material, while said second optical element is made of a glass material, wherein, in an order from said light source means, said second optical element and said first optical element are disposed in sequence, and the power of said second optical element in the sub-scan sectional plane is larger than the power of said first optical element in the sub-scan sectional plane, and wherein at least one surface of said first optical element has a non-arcuate shape in the sub-scan sectional plane so as to reduce spherical aberration to be produced at said second optical element.