Robustness of point light source approximation in lens design for light-emitting diode packages

In this study, we examined the robustness of point light source approximation in lens design for light-emitting diode (LED) packages by Monte Carlo ray-tracing simulations. We modeled three representative freeform lenses first, and then simulated the lighting performance while changing the lens-to-chip size ratio (LCR). It is found that with the decrease of LCR, the lighting performances of the three lenses are deteriorated and the illuminance uniformities are decreased. It is concluded that the robustness of point light source approximation in lens design is dependent on the lens and challenged for extended light source, especially for compact lens.