Design of a phosphor-converted LED based lighting system considering both the lighting and color uniformity

In this work, a scheme of combining an aspheric reflector and a primary packaging freeform lens in phosphor-converted lighting-emitting diode (pc-LED) based lighting system design was developed. In contrast to most of previous works in which the color and illumination uniformity of the pc-LED lighting systems were improved one by one, the developed scheme can improve both indicators simultaneously. To demonstrate the feasibility of the developed design scheme, an initially designed pc-LED optical model, with an average correlated color temperature (CCT) of about 5000 K, was constructed as the light source of the illumination system. The key ingredient to the color uniformity of the illumination system was investigated at first, and then several instances with the cut-off angle ranging from 40 to 60 degrees were further discussed. Detailed analysis shows: for each case, the CCT variation decreases from over 4000 K to smaller than 300 K and the illumination uniformity increases from a very low level to better than 80% on the target region.