| 摘要 |
A pickup lens is provided in which various aberrations are satisfactorily corrected, which can be manufactured at low cost, and which has an optical length of 10 mm or less. This pickup lens is configured by arranging, in order from the object side, a first lens (L1)with a meniscus shape with concave surface on the object side and having negative refractive power, an aperture diaphragm (S), a second lens (L2)with convex surfaces on both sides and having positive refractive power, a third lens (L3)with concave surfaces on both sides and having negative refractive power, and a fourth lens (L4)with convex surfaces on both sides and having positive refractive power; and with the following conditions satisfied. <DF NUM="(1)">+5.0 < (r2+r1)/(r2-r1) < +7.0 </DF> <DF NUM="(2)">0.15f < d1 < 0.3f </DF> <??>Here r1 is the radius of curvature of the object-side surface of the first lens in the vicinity of the optical axis (axial radius of curvature), r2 is the radius of curvature of the image-side surface of the first lens in the vicinity of the optical axis (axial radius of curvature), d1 is the thickness of the first lens, and f is the focal length of the entire system. <IMAGE> |
