| 摘要 |
An image reading apparatus with an image reading lens configured to reduce a field curvature and a magnification error in the sub-scan direction, includes a photoelectric conversion element having picture elements arrayed in the main-scan direction, and an image reading lens for imaging imagewise information on a surface of an original, upon a light receiving surface of the photoelectric conversion element, the image reading lens including at least one anamorphic lens having anamorphic surfaces formed at a light entrance surface and a light exit surface thereof, respectively, wherein, when a sectional shape of the anamorphic surface in a main-scan section which contains an optical axis of the image reading lens and the main-scan direction, is taken as a meridional, a curvature of a sagittal of the anamorphic surface defined within a plane being perpendicular to the main-scan section and containing a normal to the anamorphic surface at an arbitrary position in the meridional direction, changes continuously along the meridional direction from the optical axis.
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