Computer Aided Spectacle Lens Design

Abstract

The ability of the human eye to accommodate (i.e. to see both near and far objects sharply) decreases with age. In order to correct this defect so called progressive-addition lenses (PAL) have been developed. The desired properties of the PAL are expressed by curvature properties of the front surface of the lens. Thus optimal lenses are characterized by curvature constraints to the geometry. Construction of the geometry is performed using a penalty method. A suitable error functional, penalizing the deviation from the optical specifications has to be established. It is shown how to efficiently minimize this error functional iteratively. The combination of geometry reconstruction and optimization provides a useful tool for the main design loop of PALs. The system has been developed and implemented in close cooperation with the optical industry.