Patent ID: 8534834
Filing Date: 2013-09-17
Classification: G01M,G02C

Abstract:
1. A method of designing a progressive addition lens, comprising: setting an amount of inward movement of line-of-sight OI and an amount of design inward movement DH to satisfy an expression OI<DH; wherein: setting the amount of inward movement of line-of-sight OI, as a target, and a pupil diameter E; substituting the amount of inward movement of line-of-sight OI as an initial value of the amount of design inward movement DH; obtaining an average power distribution and an astigmatism distribution of the lens designed by the substituting the amount of inward movement of line-of-sight OI step; obtaining a new smoothed average power distribution and a new smoothed astigmatism distribution by performing smoothing processing on the average power distribution and the astigmatism distribution obtained in the previous step within the area of the pupil diameter E; grasping the amount of inward movement VH of a peak position VN of the smoothed average power or the smoothed astigmatism, which are smoothed along the profile curve in horizontal direction H passing through the point ON in the principal line of vision; obtaining an amount of error of inward movement, which is a difference (VH−OI) between the amount of inward movement VH of the peak position obtained in the previous step and the amount of inward movement of line-of-sight OI; repeatedly performing calculation by changing the value of the amount of design inward movement DH until the absolute value of the amount of error of inward movement (VH−OI) obtained in the previous step is within a predetermined threshold, considering that the amount of inward movement VH of the peak position has substantially converged at the amount of inward movement of line-of-sight OI if the absolute value of the amount of error of inward movement (VH−OI) is within the predetermined threshold, and completing processing; and subsequently forming the progressive addition lens.