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Optical Engineering

Freeform surface design for a light-emitting diode-based collimating lens
Author(s): Jin-Jia Chen; Chin-Tang Lin
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Paper Abstract

A freeform collimating lens is designed to project light rays emitted from an LED light source to a far target plane. Generally, the projection distance is assumed to be more than 100 m, and the light beam to have negligible divergence. The lens consists of a total internal reflection (TIR) side surface, a spherical surface in the rear, a vertical plane surface in the outer part of the front, and a freeform refractive surface in the central part of the front. Light rays emitted from the LED source with large spread angles hit the TIR surface and are redirected parallel to the light axis, and those having small spread angles will be collimated by the freeform refractive surface, which is designed with a simple approximation method, and then travel parallel to the light axis. Computer simulation results show that an optical efficiency of 81.5% is achieved under a view angle of ±5 deg and for a 1 mm×1 mm LED source.

Paper Details

Date Published: 1 September 2010
PDF: 8 pages
Opt. Eng. 49(9) 093001 doi: 10.1117/1.3488046
Published in: Optical Engineering Volume 49, Issue 9
Show Author Affiliations
Jin-Jia Chen, National Changhua Univ. of Education (Taiwan)
Chin-Tang Lin, National Changhua Univ. of Education (Taiwan)


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