Y. Shaoyun, X. Sun, L. Xia, and C. Du, "LED Lighting Freeform Lens for achieving Octagon Spot,"
in Renewable Energy and the Environment,
OSA Technical Digest (online)
(Optical Society of America, 2013), paper JM3A.24.
To decreasing the design error caused by the point source model, a method combining freeform and aspherical surface is presented. A LED spotlight lens for realizing octagon spot is designed, manufactured and tested.