PROGRESSIVE REFRACTIVE POWER LENS

摘要

An additional aspherical surface amount is defined by a sum of the optimum amount at a distance portion and the optimum amount at a near portion on a progressive refractive surface. Assuming that the ratio is taken as alpha : beta , the additional aspherical surface amount is added to the progressive refractive surface in such a manner that alpha and beta satisfy a relationship of alpha + beta = 1. With this configuration, in the case where an aspherical shape is added to a progressive power lens for correcting visual acuity for the purpose of improving the optical performance and thinning the lens, the optimum aspherical shape can be given not only to a region along a main meridian line but also to the whole of the progressive refractive surface. <IMAGE>