| 摘要 |
A compact two-group zoom lens that corrects aberrations in the visible and the near-infrared regions and that provides a comparatively high aperture ratio includes, in order from the object side, a first lens group of negative refractive power and a second lens group of positive refractive power. Both lens groups include three lens components and four lens elements. The first lens group includes, in order from the object side, lens elements having negative, negative, negative, and positive refractive powers, respectively. The second lens group includes, in order from the object side, lens elements having positive, positive, negative, and positive refractive powers, respectively. Aspheric surfaces are disclosed. Certain conditions relating to the focal lengths of the two lens groups, and the index of refraction and Abbe number of one lens element are satisfied to control aberrations in both the visible and the near-infrared regions.
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