| 摘要 |
PROBLEM TO BE SOLVED: To obtain a telephoto lens system in which an object to be examined located at a limited range is highly precisely examined and image processed, and stable resolution performance having less focal movement is obtained when the wavelengths of the light source are for the wavelengths of the visible light beams and the wavelengths of the mixed light beams of visible light beams and near infrared light beams. SOLUTION: The telephoto lens system consists of four groups, i.e., a first lens group having positive power, a second lens group having positive or negative power, a third lens group having negative power and a fourth lens group having positive power in order from the object side. The total system has six lenses or less and the second lens group is made of combined lenses consisting of a positive lens having a convex face toward the object side with a large curvature and a negative lens in order from the object side. The telephoto lens system satisfies a conditional equation (1) 0.8<f2p/¾f2n¾<1.4, where f2p is the focal distance of the positive lens in the second lens group, and f2n is the focal distance of the negative lens in the second lens group. COPYRIGHT: (C)2006,JPO&NCIPI
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