| 摘要 |
PURPOSE:To improve the optical capacity of an aspherical lens when it is used as a photographic optical system, by constituting a single double convex lens so that it satisfies specific conditions. CONSTITUTION:The spherical lens is the single biconvex lens which is constituted to satisfy conditions of formulas (where r1 and r2 are the radius of curvature of the first surface and the radius of paraxial curvature of the second surface respectively and (x) is equal to X/r2 and (y) is equal to Y/r2 and X is the displacement in the direction vertical to the optical axis and Y is the displacement from the apex of the second surface in the direction of the optical axis) and has the examiner-side surface formed to an aspherical surface. It is necessary that a ratio of radius of curvature of the first surface to the second surface satisfies the condition of the formula (1) for the purpose of compensating various aberrations equally, and the condition of the formula (2) is required in the condition of the formula (1) for the purpose of compensating various aberrations well.
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