Polarization recovery system based on light pipes

With the availability of small arc size high intensity discharge lamps a new polarization recovery system using polarization recycling in a light pipe is made possible. Combining light integration/homogenization with polarization recovery in an integrator rod leads to cost reduction and smaller light engines. The polarization recovery light pipe utilizes a reflective polarizer that works at normal incidence at its exit face and a high-reflective mirror with a transparent circular aperture at the entrance face. The reflected linearly polarized light is recycled by rotating its polarization by 90degrees during one round-trip in the integrator rod. Different possibilities for achieving this polarization rotation, including retarders and phase control coatings are investigated. As much as 70% of the rejected polarized light can be recaptured with this system.