Numerical and experimental study of lens manufacturing based on electrohydrodynamics for light-emitting diodes

In this study, a new lens fabricating method based on electrohydrodynamics (EHD) was proposed and demonstrated for light-emitting diodes (LEDs). In such a lens fabricating method, the normal stress on the air-liquid interface was induced and adjusted by the electric field applied around liquid lens material. Through controlling this interface stress, the lens could be tailored into desired morphologies. A numerical model for the silicone lens fabricating process has been built. Simulation results show that three kinds of desired lens morphologies such as cone, ellipse and asymmetry can be achieved by plate-plate, ring-plate and nonaxisymmetrical cylinder-plate electrode pairs, respectively. After that, experiments were conducted to verify simulation results. Cone, ellipse and asymmetry lenses were obtained by experiments. The characteristics in detail of each of morphologies were significantly and accurately regulated. The maximum relative height variation reaches 29.6%, 16.7%, and 7.4% for the cone, ellipse and asymmetry lenses, respectively. And fabricated lenses based on EHD have high surface quality with average roughness less than 5nm.