Bulg. J. Phys. vol.27 no.1 (2000), pp. 007-012

State of the Art Optimization of Spectacle Lenses (PAL)

W. Haimerl, P. Baumbach
Research and Development Ophthalmic Lenses, Optische Werke G. Rodenstock, Munich, Germany
Abstract. The crystalline lens in the human eye loses its ability to accommodate to different distances with growing age (presbyopia). Progressive addition lenses (PALs) help in compensating this lost ability. They have a continuously increasing optical power from their upper to their lower part. Latest production technologies make it possible to grind and polish even highly complex aspherical surfaces without iterations. For the first time this allows lens manufacturers to integrate individual parameters of the spectacle wearer into the optimization instead of using average values. Designing PAL 's optics is a complex optimization process with several thousand variables describing the progressive surface. The merit function contains locally weighted optical properties and is calculated by ray- and wave tracing in a computer simulation of the so-called position of wear. The best set of variables is found in a least squares sparse matrix optimization started immediately after ordering of the spectacles. This new online optimization and production technology leads to a significantly better optical performance of progressive addition lenses.

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