| 摘要 |
PROBLEM TO BE SOLVED: To provide a compact optical scanner equipped with an fθlens having short entire length L and having high optical performance even when a focal distance (f) is increased to prolong scanning line length W. SOLUTION: The optical scanner is equipped with a collimator lens 2, a cylindrical lens 3, a light deflector 5, the fθlens 6 and an anamorphic lens 10. The lens 6 is constituted of three groups being five lenses, that is, a 1st doublet 7 obtained by sticking a 1st lens 7A and a 2nd lens 7B, a 2nd doublet 8 obtained by sticking a 3rd lens 8A and the 2nd lens 7B and a 5th lens 9 having positive power. The lens 6 is constituted to satisfy relational expressions; L/f<0.100 and 0.04≤r1/r4≤0.31. Provided that L: the entire length of the lens 6, f: the focal distance of the lens 6, r1: the radius of curvature of the refractive surface of the lens 7A on a light incident side and r4: the radius of curvature of the refractive surface of the lens 8A on the light incident side. COPYRIGHT: (C)2004,JPO
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