Led Secondary Light Distribution Design

The design of LED illumination plays an important role in LED's prevalence and the complete realization of green illumination. But it is difficult to provide a uniform irradiance and achieve high efficiency simultaneously.Traditional imaging optics focuses on imaging quality, but for the optical design of LED, the key points are uniform irradiance and power efficiency, so it is necessary to use non-imaging optics theory to design optical system. And with the illumination soft wares, only simulation and no optimization can be done.Based on the research of the relationship between the aperture angle and the height of ray on the imaging surface, this paper discusses a method to optimize aspheric lens which can be used in the commercially available software ZEMAX. The process of research is as following. First, for Lambertian and non-Lambertian light source, testify the relationship with formulas. And the result illustrates that the uniform irradiance distribution can be achieved by changing the weights of rays with different aperture angles. Second, according to the theory of least squares, a merit function is programmed and integrated into ZEMAX. Last, this method is applied in a practical project: by debug the weights of rays, round and ellipse faculae are achieved with a real LED light source. By simulating the optical system and analyzing the irradiance distribution in the illumination design software of ASAP, the method is verified again.