Abstract: A variable retarder is inserted in one or more light channels of a kernel. The variable retarder is a nematic liquid crystal layer that is energized by an electric field and, for example, the voltage or frequency of the electric field dictates an amount of retardation effected by the variable retarder. The variable retarder either increases or decreases an optical path in which it is inserted relative to a reference. The amount of increase or decrease is utilized to place light paths in the kernel within acceptable tolerances. The acceptable tolerances are, for example, a tolerance of difference-light paths expected by a projection lens of device using the kernel for light modulation. In one embodiment, the variable retarder includes a polymer that can be used to fix a retardation value of the variable waveplate.

Abstract: A transmissive LCD is placed in optical series with pixels of an image. The transmissive LCD is set to full transmissivity when bright pixels of the image pass through the transmissive LCD. Transmissivity is decreased where pixels darker than a darkening threshold pass through the transmissive LCD. A darkening curve representative of an amount of darkening performed by the transmissive LCD provides an amount of darkening to be performed on each pixel. Preferably, the darkening curve gradually darkens pixels more as the pixels themselves are darker. The darkening curve may be implemented as a formula or a look-up table in software or drive electronics that energize the transmissive LCD. Both the darkening threshold and the darkening curve may be user selectable.

Abstract: A variable retarder is inserted in a polarized light beam. The retardance of the variable retarder is increased when the light beam increases in brightness and is decreased when the light beam decreases in brightness. The amount of increase and/or decrease in retardance is calculated to stabilize the brightness of the light beam. The variable retarder may be used in conjunction with an auto-iris and share a same brightness detector.

Abstract: Ultra Violet (UV) light produced by a light source is converted to visible light and utilized in a visible light output of the light source. The light source is, for example, a light source in an illuminator of a projection device. UV light that is typically filtered out of the illuminator is converted by a UV absorbing visible light radiating phosphor. The UV light is directed to the phosphor by, for example, reflecting the UV light out of a light path, concentrating the UV light via a concave reflector, and directing the UV light to the phosphor. The re-radiated visible light is then injected back into the light path of the light source. In one embodiment, the re-radiated visible light is injected into a “shadow” of the light path.

Abstract: A hollow sphere with a scattering (e.g., white diffusive) interior surface directs light input from at least one input light source to an exit. The exit has a reflective polarizer that passes light of a selected polarization to an output. Light of other polarization(s) is reflected back into the sphere where it becomes unpolarized because of reflections and may eventually be returned to the exit at the selected polarization. The illuminator is well suited as a light source for light management systems of various configurations.

Abstract: Images to be displayed are produced for left-eye viewing and right-eye viewing in synchronization with a polarization device that alternately changes polarization of the viewed images. In one embodiment, a control mechanism synchronizes modulation performed by microdisplays in a reflective Liquid Crystal On Silicon (LCOS) kernel with an electronically controlled shutter that alternately converts light output from the LCOS kernel between S and P polarizations. Prior to reaching the shutter (or other polarization switching device) a wavelength specific retarder is utilized so that the polarizations of various light channels are homogenous. The kernel installed in, for example, a 3-D enabled monitor, 3-D gaming device, or a 3-D enabled High Definition (HD) LCOS Rear projection television (RPTV).

Abstract: Frames are used to hold and/or position components in precise positions in a prism assembly. The frames may be constructed using any of side caps, air gaps, recesses, and hold either a single or multiple planar components. The frames are, for example, immersed in liquid filled channels between adjacent faces of beamsplitters in the prism assembly. The planar components themselves may include waveplates, optical flats, spacer glasses, retarders, Color Selects, substrates, or any other components of the optical device. The planar components may themselves include multiple layers (e.g., polarizers, dichroics, etc). In one embodiment, a polarizer and an air gap are provided. The invention increases precision, lowers cost, and improves quality (e.g., contrast ratio) of any number of devices, but is particularly applicable to Liquid Crystal on Silicon (LCOS) and other microdisplay based projection systems such as High Definition (HD) Rear Projection Televisions (RPTVs).

Abstract: An absorptive layer is added to an image display system. The absorptive layer is selected to compensate for tint in a black state of a displayed image. In a Liquid Crystal On Silicon (LCOS) based light engine, blue wavelengths may cause a predominate tint in black portions of an image (or an entirely black image is tinted blue), and the absorptive layer is calculated to absorb an amount of blue equivalent to the tint. The absorptive layer is, for example, an unbalanced magenta dichroic, or a yellow filter. The yellow filter may be placed at any point in the light chain, including input/output of a kernel, input/output of a projection lens, or portions of a light engine or display screen. An unbalanced magenta may be constructed by adding a yellow filter to an existing magenta dichroic in the kernel design.

Abstract: Kernels are designed in different configurations based on design properties of an enclosure or other requirements. A prism assembly having various types of filters, waveplates, beam splitters (e.g., path length matched beam splitters) and/or other optical components are provided to selectively direct light beams to each of red, green, and blue microdisplays that manipulate the light and then combine the manipulated lights into an output image. The prism assembly includes an input face, an output face, and other faces on which the microdisplays are attached in a number of different configurations. Requirements and exact placement of optical components varies depending on which microdisplay is attached to which face. The components of the prism assembly may be arranged in path length matched positions.

Abstract: A variable retarder and linear polarizer are placed in series in a polarized light path. A transmission axis of the linear polarizer is parallel to an axis of a polarization of the polarized light. An amount of retardation dialed into the variable retarder causes an amount of the light to have a component with an amount of off axis polarization. The off-axis components do not pass the linear polarizer, causing a reduction in the brightness of the polarized light. The combined variable retarder and linear polarizer operate as a light shutter that may be utilized, for example, to increase contrast ratio and bit depth regardless of light level in a video projection system (e.g., LCoS light engines).

Abstract: A Liquid Crystal on Silicon (LCOS kernel for a light engine is configured in a kernel having light paths in three dimensions (3D kernel). The 3D kernel allows for designs that do not require Wavelength Dependent Waveplates (WDWs) (or Wavelength Specific Retarders) for managing light polarizations within the 3D kernel. In one embodiment, the 3D kernel includes a Polarizing Beam Splitter (PBS) that is positioned to direct lightpaths within the 3D kernel in the 3rd dimension (e.g., light path planes perpendicular to planes of input light provided to the 3D kernel). The 3rd dimension is, for example, an output light path perpendicular to an input light plane. The 3D kernel allows for designs that incorporate reflective LCOS microdisplays and management of light paths without WDWs. The kernel is suitable for use in High Definition (HD) LCOS Rear Projection Televisions (RPTVs) and other projector applications.

Abstract: A hollow sphere with a scattering (e.g., white diffusive) interior surface directs light input from at least one input light source to an exit. In one embodiment, an internal hot mirror and phosphor are positioned to intercept the input light on which visible light is reflected and ultraviolet light is directed to the phosphor for conversion to visible light. The exit has a reflective polarizer that passes light of a selected polarization to an output. Light of other polarization(s) is reflected back into the sphere where it becomes unpolarized because of reflections and may eventually be returned to the exit at the selected polarization.

Abstract: A transmissive LCD is placed in optical series with pixels of an image. The transmissive LCD is set to full transmissivity when bright pixels of the image pass through the transmissive LCD. Transmissivity is decreased where pixels darker than a darkening threshold pass through the transmissive LCD. A darkening curve representative of an amount of darkening performed by the transmissive LCD provides an amount of darkening to be performed on each pixel. Preferably, the darkening curve gradually darkens pixels more as the pixels themselves are darker. The darkening curve may be implemented as a formula or a look-up table in software or drive electronics that energize the transmissive LCD. Both the darkening threshold and the darkening curve may be user selectable.

Abstract: Optical components are louvered with a light absorptive material that absorbs stray light rays. The louvers are constructed, for example, using a “black” thin film coating between sheets of glass. The louvered components are placed in an optical path at one or more orientations. In one embodiment, a vertically oriented louvered component and a horizontally oriented louvered component are individually located in a light path to reduce and/or eliminate stray light having either horizontal and/or vertical vector components. Compensated higher order waveplates are constructed from birefringent material by placing two higher order waveplates (a n? waveplate and a (n+?)? waveplate.) in proximity to each other such that their principle retardation axes are perpendicular. In one embodiment, the higher order waveplates include louvers for stray light suppression.

Abstract: A lens array is placed over a cover glass of a pixel based LCoS display device. The lens array is situated so that an individual lens in the array corresponds to an individual pixel in the display device. Each lens collects light and/or reflections from a high contrast portion of its corresponding pixel and forwards it to a viewing area. The lens array reduces effects of low contrast portions of the pixels (particularly, for example, perimeters of adjacent pixels having relatively large differences in electrical field strengths).

Abstract: Pathlength matched optical devices (such as beam splitters) are produced by viewing optical paths through the optical devices and adjusting relative positions of optical components of the optical devices until the viewed optical paths are equivalent. The optical paths begin at markings at different locations on the optical device. The optical pathlengths are equivalent when both markings are in focus in a limited field of view camera or lens. In a beam splitting cube constructed of two prisms, markings located at precisely similar locations on different prisms are pathlength matched when coincident as viewed at a reference face of the cube. The prisms are abutted at their diagonals and are adjusted by sliding the prisms along the diagonals to the pathlength matched position. Optical adhesive between the prisms is cured after fixing the prisms at the pathlength matched position.

Abstract: A pathlength matched prism assembly is constructed from Polarizing Beam Splitter optical components having varying degrees of precision by arranging them in pathlength matched positions and fixing them to a baseplate or frame. Gaps between the optical components are sealed by the frame or adhesive sealant. Planar optical elements are inserted between the optical components and space between the components and elements is filled with an optical coupling fluid having an index of refraction that closely matches the index of refraction of both components and elements. An expansion compensation device is attached to the prism assembly to compensate of expansion and contraction of the optical coupling fluid. The prism assembly is best suited for use in HDTV and High Definition video projectors.

Abstract: A beam splitter is constructed using one or more cholesteric layers. Each cholesteric layer reflects light of a given wavelength and polarization. The beam splitter is placed in a prism assembly. The cholesteric layers of the beam splitter are chosen such that portions of light entering the beam splitter are individually directed to a specific light path or to a processing face of the prism assembly. A microdisplay is mounted on each processing faces forms a kernel, and each microdisplay processes the light portions (light beams) directed toward them. Light beams reflected from the microdisplays have image content added to them from the microdisplays. The kernel is utilized in a light management system, such as that used in a video projection (e.g., projection television).

Abstract: A compensated higher order waveplate is constructed of substrates. In one embodiment, a first substrate is a n? waveplate and the second substrate is a (n+?)? waveplate. The substrates are oriented so that their principle axes of retardation are orthogonal. n? is a base retardation of a waveplate and ?? is an incremental retardation. The incremental retardation produces a desired amount of retardation of a lightwave passing through the compensated higher order waveplate. Retarder material used to produce the base retardation is approximately ½ a desired thickness of the waveplate. Multiple waveplates are combined to produce any of wavelength band specific retarders and multiple non contiguous wavelength band specific retarders.

Abstract: Kernels are designed in different configurations based on design properties of an enclosure or other requirements. A prism assembly having various types of filters, waveplates, beam splitters (e.g., path length matched beam splitters) and/or other optical components are provided to selectively direct light beams to each of red, green, and blue microdisplays that manipulate the light and then combine the manipulated lights into an output image. The prism assembly includes an input face, an output face, and other faces on which the microdisplays are attached in a number of different configurations. Requirements and exact placement of optical components varies depending on which microdisplay is attached to which face. The components of the prism assembly may be arranged in path length matched positions.