Patent ID: 7252399

Claim:
A front end unit for a light engine system comprising: a light source defined by a focal ratio for producing a high-flux converging beam of light along a first axis in free space and having a first cone angle; a lightpipe for inputting the converging beam of light and for outputting a relatively more spatially uniform beam of light along a second axis; a prism for folding the converging beam of light from the light source into the lightpipe; a polarization beam splitter between the light source and the prism for reflecting light of a first polarization into the lightpipe and for passing light of a second polarization to the prism; and a polarization rotator for rotating the polarization of the light with the second polarization to the first polarization before entering the lightpipe; wherein the prism has a larger index of refraction than the free space, whereby the converging beam of light passing from the free space through the prism has a second cone angle less than the first cone angle, effectively increasing the focal ratio of the light source, and wherein the second cone angle effectively provides extra distance between the light source and the lightpipe to enable the beam of light to be folded into the lightpipe.