2010•International Optical Design Conference and Optical Fabrication and TestingRequires access
Injecting Light of High-Power LEDs into Thin Light Guides
Hugo J. Cornelissen, Chenhung Ho, Haiyan Ma, M. P. C. M. Krijn, H. A. van Sprang
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Abstract
A new method using a thin-film multilayer filter is described to couple light from high-power LEDs into a thin light guide such as an LCD backlight. Light emitted below the critical angle is reflected back to the LED and recycled. Large-angle emitted light passes the filter and is transported by total internal reflection in the light guide. The light guide can be as thin as 0.3mm for an LED of 1×1mm2, and the best coupling efficiency is estimated to be 82%. With this approach, a backlight system can be greatly simplified but also compact collimators can be realized. In this paper the optical design and testing of the filter is described, and a 1mm thick, 6.5mm diameter collimator is presented. Measurements on prototypes show good agreement with the designed characteristics.