| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical scanner in which the thickness and an uneven thickness of a lens can be efficiently reduced while maintaining the optical performance, and which is low cost and has good performance. SOLUTION: As regards the Fresnel face of the lens, the curved surface shape (a curvature) is changed at every refractive segment as indicated in Figure (b) and tangent planes ((1) and (2) in Figure (b)) are made not parallel in the vicinity of common back cut surfaces (A and B in Figure (b)) at respective adjacent refractive segments. In a second embodiment shown in Figure (c), while the back cut surface positions are fixed, the curved surface of each refractive segment is shifted for a prescribed amount at every refractive segment in a lattice array direction and the light beam emitting angle of each refractive segment is adjusted so that occurrence of disruption of a spot diagram on the image surface is prevented. COPYRIGHT: (C)2006,JPO&NCIPI
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