| 摘要 |
A light emitting device includes a base; a light emitting diode (LED) supported by the base; a layer spaced apart from the LED and including a light emitting material of refraction index n1. An enclosure formed by the layer and the base encloses the LED. A medium inside the enclosure between the LED and the layer has a refraction index n0<n1; and an optic in contact with the layer and having a refraction index n2>=n1. The layer is positioned between the optic and the LED. The optic has, at a surface of contact with the layer, a radius r measured along a ray originating from the LED, and, at an output surface of the optic, another radius R measured along the same ray, such that R>=r·(n1/nm), where nm is a refraction index of a medium adjacent the output surface of the optic.
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