| 摘要 |
PROBLEM TO BE SOLVED: To provide a diffraction optical element with which desired optical performance is obtained at a low cost, an optical scanner which suppresses mis-focusing due to a temperature change by using such diffraction optical element in an optical system, and an image forming apparatus. SOLUTION: The diffraction optical element is used for the optical system for condensing the luminous flux from a light source onto an image plane, is made of a resin to obtain prescribed power by diffracting the incident luminous flux and has a plurality of slopes to generate the powder and wall section 4, 4', etc., between the slopes. The extensions of the wall section 4, 4', etc., of the diffraction gratings intersect with a straight line parallel to the optical axis at one point in any places, and the slopes are non-parallel to the incident luminous flux to the diffraction gratings. The optical scanner and the image forming apparatus using such diffraction optical element made of the resin are provided. COPYRIGHT: (C)2006,JPO&NCIPI
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