| 摘要 |
PROBLEM TO BE SOLVED: To obtain an optical scanner in which an excellent image is always obtained by reducing the sensitivity of the curve of a scanning line on a face to be scanned due to an arrangement error of a scanning optical system and to obtain an image forming apparatus using the optical scanner. SOLUTION: The optical scanner is provided with: a deflection means which deflects a luminous flux emitted from a light source means; and a scanning optical system having a plurality of scanning lenses which guide the luminous flux to a face to be scanned, the shape of a first scanning lens La in a main scanning cross section is of a meniscus having a positive refractive power and the first scanning lens satisfies the condition of d1<fm<0.06, where fm stands for the focal length of the scanning optical system in the main scanning cross section and d1 stands for the thickness of the center of the scanning lens La, the surface of a second scanning lens Lb on the light incident side in the main scanning cross section has aspherical shape or circular arched shape having no inflection points and the second scanning lens satisfies the condition of 2.5<¾R3/fm¾, where R3 stands for the radius of curvature of the face on the light incident side on the optical axis in the main scanning cross section. COPYRIGHT: (C)2004,JPO&NCIPI
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