Elimination of flux loss by optimizing the groove angle in modified Fresnel lens to increase illuminance uniformity, color uniformity and flux efficiency in LED illumination

Byungwook Kim, Minseok Choi, Hokwan Kim, Jiseok Lim, Shinill Kang

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

A Fresnel lens is an optical component that can be used to create systems more compact, cost-effective, and lightweight than those using conventional continuous surface optics. However, Fresnel lenses can usually cause a loss of flux efficiency and non-uniform distribution of illuminance due to secondary refraction by surface discontinuities, especially along the groove facet. We therefore proposed to modify a groove angle in the Fresnel lens and analyzed interrelation between the groove angle and multiple optical performances, such as flux efficiency and the uniformity of illuminance and color. The groove angle was optimized to maximize the uniformity and efficiency in the target viewing angle considering various weights of merit functions. Specifically, in our study, when the uniformity of illuminance had a httle more weight than the flux efficiency (ratio of 0.6:0.4), final optimum groove angles of 24.7°, 29.4°, and 31.3° were obtained at target viewing angles of 20°, 30°, and 40°, respectively. We also fabricated a modified Fresnel lens with a groove angle of 29.4° using UV- imprinting. The real optical performance of the fabricated Fresnel lens was then compared to that of a spherical lens.

Original languageEnglish
Pages (from-to)17916-17927
Number of pages12
JournalOptics Express
Volume17
Issue number20
DOIs
Publication statusPublished - 2009 Sep 28

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics

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