Estratègia 2D per al disseny de reflectors amb facetes de forma lliure

Resumo

This work can be framed in the field of computer-aided optical systems design and it is a part of a larger project in which automated processes are studied and implemented aiming to reduce the time span that stands between the idea and the functional device. One of the problems in optical systems optimization is the need for a predesign good enough to start, so that the automatic system is effective and leads to a quality optical system. To define a general criteria for initial conditions that are valid to start a process of automatic design in the specific field of non-imaging optics, is an objective which contributes to the capacity of the industry respending to market demands . Astrategy is defined to design reflectors as non-imaging optical systems in two stages:the first stage performs the design of a single reflective freeform surface providing a predetermined light distribution.The second stage defines the method that can generate valid initial configurations for the overall design of non- imaging optical systems . In order to design a one surface freeform reflector, a 20 strategy to build 30 solutions is defined which can describe the geometry of the freeform reflector using Bezier surfaces through a simplified calculation process in 20. The process of choosing 20 planes where to apply the strategy is based on expanding the criteria on what is accepted as a solution to transport light between two points. The basis and appropriate approaches have been defined in order to go from an exact solution to a plausible solution. An alternative method is presented, which is approximate and computationallysimpler, but allows plausible solutions in the general case that the source is not placed in the plane defined by the direction normal to the facet. In this case, the projection of the source in this plane provides an acceptable solution if you choose the right working conditions. The error has been delimited when using such a projection instead of finding the exact point that corresponds to one of the ellipse's focus contained in the plane. lt is found that the error is acceptable within the purposes of the present study. Applying the formulation of Snell's law in Bezier curves placed on strategic planes, a method for calculating the control points that defines the solution as a Bezier surface is provided.For that purpose, enhancement functions responding to various purposes, such as concentrate or distribute light around the chosen target points, are used. Finally, a method to generate valid initial configurations to design non imaging optics systems is defined, in the context of a faceted reflector. A method to segment the reflector based on the source luminance distribution is described.This method must take into account, necessarily, the segmentation of the source. Finally a method to segment the target surface is also described. The proposed working method has been validated by comparing the distributions of light predicted by the method with those obtained with commercial software. This verification has been made for concentrators and expander functions, for original facets sizes between 5 and 40mm and relative inclinations of 40 degrees, with point and extended source ofvarious sizes.In all cases, the discrepancies are still under 15% (almost always less than 8%), thus it can be concluded that the proposed method of generating 30 surface from 20 strategy, gives satisfactory results using the proposed surfaces as starting point for a more complete optimization process.