Strategy to obtain initial configurations for free form reflectors design

Abstract

A strategy to obtain sets of initial configuration to design freeform reflector surfaces is presented. This strategy brings the initial configuration of the reflector surface using a collection of elemental facets defined by Bezier surfaces and able to face the optimization process of the illumination system. The purpose of this communication is to provide initial configurations to obtain a set of parameters defining the freeform facets described by Bezier curves. Those parameters can be modified by a global optimization process of the lighting system. This task can be accomplished using a set of simple geometric elements that are the basis for calculating a first approximation to the facet surface. The proposed strategy provides a simple geometric design method to perform valid initial configurations for lighting systems with reflective surfaces that can be further optimized. The method to calculate the geometry of every single facet is based on ray tracing and uses a merit function to find the parameters defining the Bezier curve that best meets specifications in each elementary facet. Applying this method to 2D tangential and sagital axes, a network of control points are obtained for describing a Bezier surface compatible with any standard optical optimization tool and suitable for viewing with CAD tools.