| 摘要 |
PROBLEM TO BE SOLVED: To provide an imaging lens which maintains a wide field angle and a short optical length held for a lens system of a two-sheet composition. SOLUTION: Disclosed is a super wide-angle lens which is constituted by arranging a first lens L1 whose surfaces are both aspherical, a stop, and a second biconvex lens L2 at least one of the surfaces of which is aspherical in this order. The lens is adaptive to a single-wavelength light source while satisfying conditions of: (1) -89.4<r<SB>1</SB>/f<-11.1; (2) 1.4<r<SB>2</SB>/f<2.2; (3) 1.5<r<SB>3</SB>/f<2.6; (4) -1.3<r<SB>4</SB>/f<-0.9; (5) -3.7<f<SB>1</SB>/f<-2.6; and (6) 2.9<d<SB>2</SB>/f<4.1. Here, (f) is the composite focal length of the whole lens system; f<SB>1</SB>is the focal length of the first lens; r<SB>1</SB>is the paraxial curvature radius of an object-side surface of the first lens; r<SB>2</SB>is the paraxial curvature radius of an image-side surface of the first lens; r<SB>3</SB>is the paraxial curvature radius of an object-side surface of the second lens; r<SB>4</SB>is the paraxial curvature radius of an image-side surface of the second lens; and d<SB>2</SB>is the inter-axis distance between the image-side surface of the first lens and the stop. COPYRIGHT: (C)2007,JPO&INPIT
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