Freeform lens predictions by a Neural Network and B-splines: Utilizing the Fraunhofer approximation to train a Neural Network unsupervised

There exist a lot of methods to find the electromagnetic field behind a lens, so called the forward lens problem. In contrast very few methods can do the inverse, namely finding a lens that would produce a given image or light distribution for a known source. Here a solution to the forward problem, the Fraunhofer approximation, is used to find...