渐进多焦点眼镜片的公差分析

渐进多焦点眼镜片能够同时满足视远与视近的需求，其应用日益广泛。介绍渐进多焦点镜片的基本结构、设计与评价方法，在此基础上根据国家标准规定的镜片有效区域实际屈光度与名义值差值小于0.1m-1的要求，对渐进多焦点镜片的面型进行了公差分析。通过对镜片面型方程及球面度方程求解偏微分推导出屈光度与面型相关的公差公式。举例对屈光度增量2.5 m-1（6.5 m-1~9 m-1）的渐进面进行设计评价与公差分析，该设计实例公差分析结果表明:面型最敏感处公差值为0.1 m，为镜片加工的控制精度提供理论依据。

Tolerance analysis of progressive addition lenses

The progressive addition lenses(PAL) have been used widely because of the advantage which can meet the requirements of distant and near vision both at the same time.The basic structure,design and evaluation method of progressive addition lenses were introduced. Based on the national standard that the difference between actual diopter and theoretical value should be less than 0.1 m-1 within the lens effective area, the tolerance analysis of progressive addition lenses was realized.The tolerance formula related to diopter and surface was derived from the surface equation and sphere equation. As an example,a progressive addition lens with 2.5 m-1 addition (6.5 m-1~9 m-1) was designed and evaluated, the tolerance was analyzed. The analysis result shows that tolerance value should be less than 0.1 m at the most sensitive area of lens surface, which provides theoretical basis for the control precision of lens processing.