Songyuan Cen

Free-form micro-lens for LED general illumination

To redistribute any patterns of LED radiation distributions onto a target surfaces to achieve a prescribed distribution, the free-form micro-lens is designed by using the “edge-ray principle”. Some modules were done, and the simulation results show that the design of free-form micro-lens is applicable in LED illumination with competitive advantages.

Effect of phosphor geometry on luminous flux of phosphor-converted LED

This paper systematically analyzes first the effect of phosphor geometry on luminous flux of phosphor-converted LED. Five phosphor geometries are investigated based on Mie-theory calculations. Results show that phosphor geometry has impact on luminous flux, and pcLED with a phosphor layer of spherically top surface achieve an improvement of 12%.

The mesopic effect of different color temperature LED light sources on road lighting

A equation, E<inf>mes</inf> = B·E<inf>p</inf>, to deduce from the Ep(photopic illumination) to E<inf>mes</inf>(mesopic equivalent illumination) is proposed, where B is instant for modified coefficient. The equation is used to calculate the mesopic equivalent illumination of the different color temperature LED light sources under mesopic light levels.