The luminance of a system that includes a light emitting diode (LED), such as a projection system, may be increased by using an LED chip that has a light emitting surface that emits light directly into any medium with a refractive index of less than or equal to approximately 1.25. For example, the LED...http://www.google.es/patents/US20050179041?utm_source=gb-gplus-sharePatente US20050179041 - Illumination system with LEDs
