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CSME 2021/04
Volume 42 No.2
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181-186
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Smooth Source-Target Maps for Freeform Lens Design for Uniform Illumination of Right Polygons
Ku-Chin Lina and Min-Hsiung Maa
aDepartment of Mechanical Engineering, Kun Shan University, Taiwan 71070, ROC.
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Abstract:
Source-target maps play the prevailing role in freeform lens design for diverse illumination applications, but very few of previous studies have taken into account the smoothness of the map. A non-smooth map may result in a freeform lens with discontinuous surfaces or surfaces with bulge/sharp edges that will greatly increase the difficulty for lens fabrication and induce large variation in the produced irradiance distribution. In this study, a map is proposed to achieve continuous and smooth freeform surfaces for uniform illumination of right polygons. The proposed map is an integration of a number of primitive maps where a polygon is divided into a number of symmetric quadrilaterals of the same size, and the irradiance energy of source is also divided into the same number of symmetric pie sectors. The transfer of a pie sector of irradiance energy onto a quadrilateral is derived. Procedures to implement the proposed map are given in this study. The adequacy of the proposed map is demonstrated by Monte Carlo ray tracing simulation and experiment as well. The contribution of this study is fundamental and profound in the field of freeform lens design. Advanced studies for uniform illumination of arbitrary polygons are currently taken to expand the applicability of the proposed map.
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Keywords: freeform lens, uniform illumination, edge-ray principle.
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©
2021
CSME , ISSN 0257-9731
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