Abstract: The present invention relates to a folded front end unit used in a light engine of a projection display device. The front end unit comprises a light source for generating a beam of light, and a lightpipe for providing spatial uniformity to the beam of light. Polarization-dependent front end units include polarization beam splitters for separating the light into orthogonally polarized sub-beams, and a polarization rotating element, e.g. a waveplate, for rotating the polarization of one of the sub-beams. In accordance with the present invention, a prism is positioned between the light source and the lightpipe for reflecting the light into the lightpipe. The difference in refractive index between the air and the prism decreases the cone angle of the beam of light enough to effectively increase the distance between the light source and the lightpipe to compensate for the added distance required to fold the light.

Abstract: A color management system for use with projection displays includes, for example, a separating polarizing beamsplitter, a compensating prism group, an image assimilator, and a combining polarizing beam splitter. In accordance with an exemplary embodiment, the separating polarizing beamsplitter receives a bi-oriented light input and separates it into two output beams, one comprising a first component and the other comprising a second component. The image assimilator receives an output light beam from the separating polarizing beamsplitter, transmits the light output to one or more corresponding microdisplays, receives one or more modified outputs from the microdisplays, and emits an output comprising those modified outputs to a combining polarizing beamsplitter.

Abstract: A reflector, light source, phase retarder, and linear polarizer configured to increase a single-polarization output beam by converting wrong-polarization light into correct-polarization light. The linear polarizer reflects the wrong-polarization light and transmits the correct-polarization light. The phase retarder converts the wrong-polarization light into correct-polarization light, which is then transmitted by the linear polarizer.

Abstract: A recirculating light polarizer utilizes a reflective polarizer on the exit face of a light integrator, such as a light pipe or light tunnel. Light is provided to the light integrator and light of one polarization is transmitted through the polarizer, the remaining light being reflected back into the integrator. The back-reflected light accumulates polarization shift before it eventually is reflected back to the polarizer. The reflected light is further homogenized on its trip back to the polarizer. This process is typically repeated several times to enhance the light output from the light pipe assembly, with some light being lost in each cycle due to various loss mechanisms. A polarization state modifier, such as a retarder plate or phase-shifting coatings, may be included in the recirculating light path to enhance polarization shift.

Abstract: A color management system for use with projection displays includes a beamsplitter positioned to receive a light beam, a microdisplay positioned to receive the light beam from the beamsplitter and emit a modified light beam to the beamsplitter, and a plurality of prisms positioned to receive the modified light beam from the beamsplitter and emit a light output that compensates for an optical aberration induced by the beamsplitter.

Abstract: A reflector, light source, phase retarder, and linear polarizer configured to increase a single-polarization output beam by converting wrong-polarization light into correct-polarization light. The linear polarizer reflects the wrong-polarization light and transmits the correct-polarization light. The phase retarder converts the wrong-polarization light into correct-polarization light, which is then transmitted by the linear polarizer.

Abstract: A color management system for use with projection displays includes an image assimilator and an analyzer. The image assimilator comprises a panel that produces a light beam comprising spatial information. The image assimilator also comprises a field lens positioned to receive the light beam and configured to emit a converging light beam whose cross-sectional area decreases with distance from the field lens. In an exemplary embodiment, a plurality of image assimilators and associated analyzers are included, each having a field lens for emitting a converging light beam. The analyzers are configured for producing filtered light outputs with improved contrast relative to the converging light beams. In addition, the converging nature of the field lens emitted light beams enables the size of the analyzers and other downstream components to be minimized. Accordingly, this embodiment produces images having dramatically improved levels of contrast with reduced size relative to prior art systems.

Abstract: A color management system for use with projection displays includes, for example, two or more analyzers positioned to receive light beams emitted from corresponding image assimilators, which each comprise a transmissive panel and a polarizing beamsplitter. Each analyzer is positioned to receive a light beam directly from an associated image assimilator before the light has passed through another optical element such as a light combiner. The analyzers are configured for producing filtered light outputs with improved contrast relative to the incoming light beams. These closely-coupled analyzers are able to remove substantially all of the noise before it has become indistinguishable, on the basis of polarization, from the light that comprises the desirable image. In an exemplary embodiment, an optical isolator is positioned to receive both a light output from a color management system and a reflection of the light output. The optical isolator is configured for isolating the light output from the reflection.

Abstract: A reflector, light source, phase retarder, and linear polarizer configured to increase a single-polarization output beam by converting wrong-polarization light into correct-polarization light. The linear polarizer reflects the wrong-polarization light and transmits the correct-polarization light. The phase retarder converts the wrong-polarization light into correct-polarization light, which is then transmitted by the linear polarizer.

Abstract: A color management system for use with projection displays includes, for example, two or more analyzers positioned to receive light beams as they are emitted from the panels of a color management system. The analyzers are positioned to receive the light beams directly from the image assimilators before the light has passed through another optical element such as a light combiner. The analyzers are configured for producing filtered light outputs with improved contrast relative to the incoming light beams. By positioning the analyzers to receive the light beams directly from the image assimilators, i.e., prior to passage through other optical elements, the analyzers are able to remove substantially all of the noise before it has become indistinguishable, on the basis of polarization, from the light that comprises the desirable image. Accordingly, this embodiment produces images having dramatically improved levels of contrast relative to prior art systems.

Abstract: A color management system for use with projection displays includes, for example, a separating polarizing beamsplitter, a compensating prism group, an image assimilator, and a combining polarizing beam splitter. In accordance with an exemplary embodiment, the separating polarizing beamsplitter receives a bi-oriented light input and separates it into two output beams, one comprising a first component and the other comprising a second component. The image assimilator receives an output light beam from the separating polarizing beamsplitter, transmits the light output to one or more corresponding microdisplays, receives one or more modified outputs from the microdisplays, and emits an output comprising those modified outputs to a combining polarizing beamsplitter.