Study on the variational-difference-based design and slow tool servo turning of progressive addition lenses

Abstract

Nowadays, progressive addition lenses are widely applied to correct people's vision disorders, but the design and machining of progressive addition lenses are still difficult. Generally, a progressive addition lens has a freeform front surface and a spherical back surface. In this article, the design of the front surface was simplified as a minimization problem of a functional, and the solution was obtained directly using a variational-difference method. After solving this problem, the description of the surface was discussed, and an evaluation method was proposed to analyze the fitting accuracy of Zernike polynomial method and B-spline interpolation method with different degrees. As a result, the progressive addition lens surface was constructed by the method with smaller fitting error. Moreover, a new generation algorithm of entrance parameters for tool path generation was put forward, which can reduce the interpolation error. The experimental results indicate that the design method was feasible and the machined surface quality was satisfactory using the proposed algorithm.

Study on Design and Diamond Turning of Optical Freeform Surface for Progressive Addition Lenses

“…ere are two main design methods, one is to model in CAD software and simplify the lens design as a functional minimization problem [15,16], and the other is a mathematical method that can directly express the surface with a series of formulas [17][18][19][20][21]. e first design method is relatively simple, but the processing of subsequent data is more complicated, and it is usually necessary to use the spline interpolation to obtain the machining coordinates.…”