CONCENTRIC CIRCULAR LENS HAVING MINIMUM ANGLE BETWEEN ADJACENT ANNULAR SEGMENTS

摘要

PROBLEM TO BE SOLVED: To provide a multifocus concentric circular lens minimized in an angle formed by annular segments adjacent to each other. ;SOLUTION: In a spherical lens provided with plural annular segments having different curvatures, the annular segments being adjacent to each other and their shifting region are machined by using a programmable numerically controlled(NC) machine tool. Either the front surface or the rear surface of a multifocus type concentric circular lens is sectioned into plural spherically annular segments having different radii of curvature and refractive powers. The radius of curvature r1 of a first spherically annular segment 32 is displaced in the longitudinal direction of optical axis 36 to the radius of curvature r2 of an adjacent second spherically annular segment 34. The first and second spherically annular segments 32, 34 are crossed at the joined part in which the difference of the angles between tangential lines drawn at the joined part becomes minimum so as to improve feeling of lens fitness and physiological acceptability.;COPYRIGHT: (C)1997,JPO