Use of free-form surface to simulate local refractive index changes in plastic lenses measured using polariscopic device

In this paper we propose a method to convert the local variations of refractive index into local changes of one surface of the lens, which then can then be described as a free-form surface, easy to introduce in conventional simulation tools. The proposed method tries to provide an equivalent model of the lens with refractive index variations where the index changes have been replaced for local thickness variations on the lens’ surface. The local thickness variations can be fitted at a freeform description that holds all the local index variations through the OPD (Optical patch difference) using a B-Spline description and a simplex algorithm to find the best fitted surface.