An inverse method to compute freeform optical surfaces for generalized zero-étendue sources

We present an inverse method to compute freeform reflector and lens surfaces for generalized zero-étendue sources. The initial position and direction of a light ray is parameterized by two source planes and the final position and direction of a light ray is parameterized by two target planes. We use energy conservation to determine optical mappings, and we use the optical path length to derive equations for the optical surfaces. In two numerical examples, we illustrate the algorithm’s capabilities to tackle complex light distributions.