Patent ID: 7740375

Claim:
An illumination device, comprising: an incoherent solid state light source adapted to emit light over at least one light emission surface and having a total light emission surface area S 0 , a solid light guide having an entrance aperture adapted to receive the light from the incoherent solid state light source and a first surface that is configured to reflect the light within the solid light guide by total internal reflection, and a light extraction device adapted to extract the light from the solid light guide and output the light from the incoherent solid state light source, wherein: the light extraction device has a refractive index that substantially matches a refractive index of the solid light guide, and includes: a first surface area S 1 that is in optical contact with the solid light guide and extracts the light by preventing the total internal reflection at the surface area S 1 , and a second surface area S 2 that outputs the light; and the first surface area S 1 is substantially smaller than the surface areas S 0 and S 2 , and the second surface area S 2 is substantially smaller than the surface area S 0 , such that an apparent brightness of the light output at the second surface area S 2 is substantially larger than an apparent brightness of the light source.