| 摘要 |
PROBLEM TO BE SOLVED: To obtain an imaging lens having a short total length even though having a three-lens construction and capable of obtaining satisfactory optical performance. SOLUTION: In the imaging lens wherein a first lens L<SB>1</SB>having positive refraction force, an aperture diaphragm 3, a second lens L<SB>2</SB>having positive refraction force and a third lens L<SB>3</SB>for compensating aberration are disposed sequentially from an object side, a diffraction optical surface is provided on at least one surface of the first lens L<SB>1</SB>or the second lens L<SB>2</SB>and the diffraction optical surface is formed so that the sum total number of cycle zones in a region through which effective rays pass is≤20. COPYRIGHT: (C)2007,JPO&INPIT
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