Hierarchical-genetic-algorithm-based design of a large scale Fresnel lens for a reading light system with multiple LED sources

Abstract

A conventional Fresnel lens is suitable to be used in the reading light system due to its features of directing and collecting light rays, as well as its properties of being essentially flat, plastic, lightweight, and cost efficient. However, it is not suitable for a reading light system with multiple light sources. To a reading light system with multiple light sources, a Fresnel lens with suitably designed groove angles can be used to improve the performance of that system in both illuminance and uniformity. Nevertheless, suitable groove angles are rather difficult to find if a Fresnel lens consists of a lot of groove angles and each angle covers a wide range of degrees. We develop a hierarchical genetic algorithm (HGA) to search for a set of optimal groove angles to design a Fresnel lens for a reading light system with multiple light sources from an enormous searching space. In addition, the groove angles of the Fresnel lens are directly derived from a conventional Fresnel lens database. The design goal is to maximize the illuminance and simultaneously maintain the uniformity of light rays incident to a specified reading surface. As a result, we can demonstrate that a HGA really works better than a genetic algorithm and the optimally designed Fresnel lens, indeed, offers a better light-guiding performance than a conventional Fresnel lens for a multiple-LED reading light system.

Optimal design of Fresnel lens for a reading light system with multiple light sources using three-layered hierarchical genetic algorithm

“…According to the design concept of the previous work 12 , the segmentation of grooves played an important role in reducing the searching space. However, the grooves in a Fresnel lens database were segmented into fixed-length segments there.…”

“…To deal with the problem given above, one way is to design a particular Fresnel lens to fit a light system with multiple light sources, i.e. searching for a special set of groove angles for a Fresnel lens 6,11,12 . However, it seems to be not an easy task because the searching space may become very large if the number of Fresnel lens's grooves is big and the range of a groove's angles is wide.…”

“…Therefore, how to find out a solution as an optimal set of groove angles from such an enormous searching space is accurately a challenging task. In the previous work 12 , we proposed a two-layered Hierarchical Genetic Algorithm to solve the problem of an enormous searching space. The first layer of a chromosome consisted of a series of control genes.…”

“…10Part of a special chromosome in 3LHGA for N seg =334.2 Implementation of 3LHGAIn actual implementation of 3LHGA, an initial population with N p chromosomes is generated first[8][9][10]12 . The values of control genes of the first layer in every chromosome are set from 1 to N seg in sequence to let parametric genes start with groove angles as the typical Fresnel lens database.…”

Design a linear irregular Fresnel lens to thin an LED-based direct-type backlight module and improve the illuminance and uniformity of LCD panel

“…1 is constructed from a lens, only suitable to a point light source, but not suitable to multiple-LED sources. To solve the limitation of a typical Fresnel lens, we have developed variant irregular Fresnel lenses for small, medium, and large circular lighting systems [1][2][3][4][5]. Since they were all developed based on a typical Fresnel lens, they are circular.…”