A typical Fresnel lens is not suitable to a reading light system with multiple light sources since it is designed in such a way that each groove is at a slightly different angle from the next but with the same focal length. Therefore, a Fresnel lens with suitably designed groove angles is needed for this kind of light system. In this paper, a more efficient three-layered Hierarchical Genetic Algorithm (3LHGA) is proposed to find an optimal set of groove angles for a designed Fresnel lens to optimize both the illuminace and uniformity for a reading light system with multiple light sources. The groove angles of a designed Fresnel lens are directly derived from a Fresnel lens database by two layers of control genes in the proposed 3LHGA. The proposed 3LHGA not only makes it possible to evolve a lot of groove angles as parametric genes but also further improve the performance of a Fresnel lens and increase the speed of evolution. From the simulation results we can demonstrate that the designed Fresnel lens indeed offers improvement of light-guiding performance for a multiple-LED reading light system.

Date Published: 21 September 2006
PDF: 13 pages
Proc. SPIE 6355, Advanced LEDs for Solid State Lighting, 63550A (21 September 2006);

Published in SPIE Proceedings Vol. 6355:
Advanced LEDs for Solid State Lighting
Chang-Hee Hong; Tsunemasa Taguchi; Jung Han; Lianghui Chen, Editor(s)