| dc.description.abstract | Applications for UV LEDs are very different from other wavelengths of LEDs, so some unique requirements for UV LEDs must be considered when some optical designs are needed. Unlike general lighting, industrial applications for UV LEDs usually focus on irradiance. However, it is nearly impossible to have high light extraction efficiency and high irradiance at the same time under the same chip size. Furthermore, the light extraction efficiency of the package design is related to the radiant flux, and the light-emitting angle of the packaged optical element is related to the irradiance.
Generally speaking, UVC LED packaging is a combination of metal concave cup ceramic substrate and flat quartz cover. However, the light extraction efficiency is poor under the general packaging. The most important topic rests in how to design and develop a UV LED packaging that can improve the light extraction efficiency.
In this thesis, methods of improving light extraction efficiency and irradiance of LED will be first discussed, and then the comparison will be made between common UVC LED packages on the market by several optical characteristics, such as radiant flux, irradiance and light angle. In our work, seven types of common packaging structures for UVC LEDs are listed and discussed. By optimizing one of the above packaging structures, various optical measurements and comparisons are analyzed. Finally, the light extraction efficiency of the optimized packaging structure increases about 8.7% and the irradiance increases about 103%. | en_US |