Abstract: Single imager projection systems suffer from low light throughput, compared to three imager systems, because only one color band is illuminated at any one time. As a result, there is a need to increase the operating efficiency of the single imager projection system. The invention is directed to the incorporation of a high extinction ratio pre-polarizer, such as a compensated, multi-layer polarizer, in a single or dual imager projection system. This permits illumination with low f-number illumination light, and thus increases the efficiency of the projection system. The pre-polarizer may be incorporated within a polarization recovery unit to further enhance system efficiency.

Abstract: A projection system includes a projection lens unit, a color combiner, and at least a first and a second image-forming devices for generating single color images. The single color images are combined in the color combiner to produce a colored image light beam. The colored image light beam passes from the color combiner to the projection lens system. A polarization control element is disposed between the color combiner and the first image-forming device. The polarization control element alters the polarization of light at either one of the first and second color, while not altering the polarization of light of the other of the first and second color. In some embodiments, the polarization control element is oriented to substantially prevent light at the second color from passing from the color combiner to the first image-forming device via a polarizing beamsplitter.

Abstract: A projection system includes an image-forming device and a polarizing beamsplitter. Illumination light illuminates the image-forming device via the first polarizing beamsplitter. A retardation element is disposed between the image-forming device and the polarizing beamsplitter. A bias controller applies a bias to pixels of the image-forming device in the dark state so as to substantially maximize contrast in image light reflected from image-forming device. In some arrangements, the volume between the polarizing beamsplitter and the image-forming device is sealed, with the retarding element being disposed within the sealed volume and being attached to either the polarizing beamsplitter or the image-forming device.

Abstract: Some projection systems use a polarization beamsplitter (PBS) for coupling light to and from an image-forming device. The PBS is typically formed with a reflective polarizing layer disposed between glass covers. Stress birefringence in the glass cover lying between the reflective polarizing layer and the image-forming device can reduce the image contrast of the projection system. A quarter-wave retarding element positioned between the glass cover and the image-forming device is used to compensate for the birefringence, at least in part. This permits the PBS to use glass covers formed of a glass material having a higher stress optic coefficient than before, while still maintaining high image contrast.

Abstract: A projection system including an intrinsic polarizer is disclosed. The projection system includes a light source producing illumination light, an imager disposed to receive the illumination light, and a projection lens disposed to receive the illumination light from the imager. The imager includes an intrinsic polarizer. An intrinsic polarizer stack including a U.V. curable adhesive is also disclosed.

Abstract: A projection engine uses a first polarizing beam splitter (PBS) that substantially reflects light incident along a first input direction in a first polarization state and substantially transmits light incident in the first input direction in a second polarization state orthogonal to the first polarization state. The first PBS demonstrates an angularly dependent reflectivity for light in the second polarization state that is asymmetric about the first input direction. At least two imager devices are positioned to receive light reflected and transmitted by the first PBS respectively. The imager devices modulate the incident light with an image. The image light from the imagers is combined and projected.

Abstract: An optical imaging system including an illumination system, a Cartesian PBS, and a prism assembly. The illumination system provides a beam of light, the illumination system having an f/# less than or equal to 2.5. The Cartesian polarizing beam splitter has a first tilt axis, oriented to receive the beam of light. A first polarized beam of light having one polarization direction is folded by the Cartesian polarizing beam splitter and a second polarized beam of light having a second polarization direction is transmitted by the Cartesian polarizing beam splitter. The Cartesian polarizing beam splitter nominally polarizes the beam of light with respect to the Cartesian beam splitter to yield the first polarized beam in the first polarization direction. The color separation and recombination prism is optically aligned to receive the first polarized beam. The prism has a second tilt axis, a plurality of color separating surfaces, and a plurality of exit surfaces.

Abstract: A polarizing beam splitter (PBS) includes a multilayer reflective polarizing film, a pressure sensitive adhesive is disposed on the multilayer reflective polarizing film, a first rigid cover is disposed on the pressure sensitive adhesive. The PBS can be used in a variety of applications.

Abstract: A compound polarization beam splitter (33) for use with a reflective, polarization-modulating, imaging device (10), e.g., a LCoS device, is provided. The compound PBS has: (a) an input prism (20); (b) an output prism (30), and (c) a polarizer (13), which is located between the two prisms (20,30) and which may be a wire grid polarizer (13a) or a multi-layer reflective polarizer (13b). Polarized illumination light (11) enters the input prism (20) through a first surface (21) and undergoes total internal reflection at a second surface (22) before being reflected from the polarizer (13) and polarization-modulated at the imaging device (10). The polarizer's tilt angle (?) is less than 45°, which reduces astigmatism and the required back working distance of the system's projection lens (74).

Abstract: The present invention provides a unique polarizing beam splitter (PBS) that is suitable for use in projection systems and displays. The PBS contains at least one prism having at least one major surface and having a refractive index of at least about 1.6 and a birefringent film disposed on the major surface of the prism. The birefringent film is a multi-layer film having at layers of at least a first material and a second material. After uniaxial stretching, the film exhibits a refractive index difference of less than about 0.15 units in the stretched direction.