| 摘要 |
PROBLEM TO BE SOLVED: To provide a cemented lens capable of suppressing focus shift between visible-ray shooting and near-infrared shooting.SOLUTION: A cemented lens with positive power comprises an object-side lens having negative power and an image-side lens having positive power cemented together by a resin adhesive layer, where each of the object-side lens and the image-side lens has aspherical surfaces, an image-side lens surface of the object-side lens and an object-side lens surface of the image-side lens having different aspherical shapes. The cemented lens satisfies conditional expressions (1) and (2): 20 μm≤D ...(1), Sg1H<Sg2H ...(2), where D represents a thickness of the resin adhesive layer on an optical axis, Sg1H represents a sag amount of the image-side lens surface of the object-side lens at a height H within an effective diameter of the image-side lens surface of the object-side lens in a direction perpendicular to the optical axis, and Sg2H represents a sag amount of the object-side lens surface of the image-side lens at the height H. Using two aspherical surfaces as an interface of the junction dramatically increases design flexibility and enables aberration correction over a wide wavelength range.SELECTED DRAWING: Figure 1 |
