Angular color uniformity enhancement of white light-emitting diodes integrated with freeform lenses.
We demonstrate a freeform lens to enhance the angular color uniformity (ACU) of white light-emitting diodes (LEDs) whose phosphor layers were coated by freely dispersed coating processes. Monte Carlo ray tracing simulation results indicated that the ACU of the modified LED integrated with the freeform lens significantly increased from 0.334 to 0.957, compared with the traditional LED. Enhancement of ACU reached as high as 186.5%. Moreover, the ACU of the modified LED was not only at a high level, but also stable when the shape of the phosphor layer changed. The freeform lens provided an effective way to achieve white LEDs with high ACU at low cost.
Wang
Kai
K
Division of MOEMS, Wuhan National Laboratory for Optoelectronics, Wuhan 430074, China.
Wu
Dan
D
Chen
Fei
F
Liu
Zongyuan
Z
Luo
Xiaobing
X
Liu
Sheng
S