| 摘要 |
<P>PROBLEM TO BE SOLVED: To acquire an image information detecting device capable of detecting a pattern image with high accuracy by taking a condition of spherical aberration of an illumination optical system into account, thereby increasing a quantity of illumination light in the central portion of an illumination area and its vicinity and hence improving the S/N ratio of a detection signal. <P>SOLUTION: The image information detecting device includes: an illumination optical system for illuminating a surface of an image carrier that is conveyed using a luminous flux emitted from light source means; a light receiving optical system for receiving light via an image formed on the image carrier; and arithmetic means for obtaining image information of an image formed on the image carrier from a signal obtained by the light receiving optical system. In the device, an optical surface of the illuminating optical system is constituted by a spherical surface, or a spherical surface and flat surface. Where "Δ" is defined as a relative distance, in a direction vertical to the surface of the image carrier, between an ideal imaging plane, which is parallel to the image carrier, and a paraxial imaging surface that is a plane parallel to the surface of the image carrier, the surface of the image carrier is positioned within the limits of plus/minus 0.5*Δ relative to the position of the ideal imaging plane. <P>COPYRIGHT: (C)2012,JPO&INPIT |
