Spectacle lenses are an important application of freeform manufacturing, with complex designs such as progressive lenses requiring nontraditional and specialized surface shapes. Such lenses also pose special challenges for optical design, as the eye’s gaze constantly changes relative to the lens. At the same time, many applications require sacrificing one region, such as the transition in a smooth bifocal, while achieving high quality in other regions. Common representations of freeform lens surfaces using polynomials or splines are poorly suited for such requirements. We describe an approach to optimize freeform spectacle lenses using a nonparametric representation of the surfaces at high resolution.
Requirements for smoothness are quantified in terms of high-order aberrations. This allows us to describe spatial variations in the design while also incorporating a constraint for optical smoothness and manufacturability. We show how this can be formulated as a regularized optimization problem incorporating raytracing, which can be solved efficiently. The approach can be used to design various kinds of lenses including progressive, bifocal, and lenticular designs. The designs have been successfully manufactured on multiple different brands of freeform generators. Manufactured lenses are found to perform as designed, including without polishing when supported by the material and generator.
Link: Optimization-of-freeform-spectacle-lenses-based-on-high-order-aberrations (pdf)