Patent ID: 7452086

Claim:
A light pipe-based projection engine comprising: a polarizing beam splitter receiving substantially un-polarized light at an input surface, the polarizing beam splitter transmitting first light energy of a useful polarization in an output direction and reflecting second light energy of a non-useful polarization in an recovery direction; a wave plate disposed in said recovery direction to receive and modify the polarization of a substantial portion of the second light energy to said useful polarization; a recovery reflector disposed reflectably to said recovery direction, said recovery reflector reflecting said second light energy in said output direction; a modulator disposed in said output direction to modulate substantially said first light energy and said second light energy; an initial light pipe disposed in said output direction to receive said first light energy from said polarization beam splitter and said second light energy from said recovery reflector and transmit said first and second light energies to said modulator; a lens disposed proximate to said output direction to focus substantially said first and second light energies received from said modulator; an output light pipe having an input surface disposed proximate to said output direction and an output surface, said output light pipe receiving said first and second light energies at said input surface from said lens and transmitting substantially said first and second light energies at said output surface; and a projection lens disposed in said output direction to collect and focus said first and second light energies from said output light pipe.