Performance comparison of a freeform lens and a CDTIRO when combined with an LED

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Original languageEnglish
JournalIEEE Photonics Journal
Issue number5
Early online date18 Jul 2017
StatePublished - Oct 2017


This paper compares the features and performance of two secondary optics when combined with an LED. The aim and application of the secondary optic are explained in the introduction section. Sections 2 and 3 introduce two optics: a freeform lens and a novel Circular Dielectric Totally Internally Reflecting Optic (CDTIRO), which can provide uniform illumination. The design process, ray tracing simulations and experimental performance of the freeform lens are described in detail in section 2. The ray tracing simulation and experimental performance of the CDTIRO are presented in section 3. Section 4 presents a comparison of the features of both lenses and their performance. Both optics can produce over 95% uniformity within an illuminated area. However, the uniformity produced by the freeform lens reduces abruptly compared with the CDTIRO when some parameters such as size and the position of the light source are changed.


  • secondary optic, freeform lens, CDTIRO, uniform illumination and LED

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