| 摘要 |
PROBLEM TO BE SOLVED: To obtain a superior optical performance by minimizing an eccentric aberration, against a specific group whose error sensitivity of the eccentric aberration is relatively large in the ordinary design, and thereby reducing error sensitivity of the eccentric aberration of a specific group. SOLUTION: Tertiary aberration coefficients corresponding to coma- aberration, astigmatism and Petzval's sum are taken as II, III and P; a group, which is relatively large in the error sensitivity of nonuniform blurred aberration against parallel eccentricity and which is constituted of lens faces from i-th to j-th from the object side, is set as a specific group; and a group on the image side from it is considered to be an image side group. In this case, the absolute value is minimized for the value which is expressed by the equation of the specific group, namely, (α'j-αi).[3.(III)R+(P)R]-αi.[3.(III)D+(P) D]--(α"#j-α#i).[3.(II)R]+α#i.[3.(II)D]. Provided that () D and () R are each sum of the tertiary aberration coefficients of the specific group and the image side group, and that the initial value of the calculation of these coefficients isα1=0, h1=1,α#1=-1, and h#1=-t.
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