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

• Main Authors: Min Kang, Jun Yang, Xingsheng Wang, Xu Chen
• Format: Article
• Language: English
• Published: SAGE Publishing 2018-12-01
• Series: Advances in Mechanical Engineering
• Online Access: https://doi.org/10.1177/1687814018815374

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.