Abstract: An optical tracking system comprises an array of point source emitters that output respective optical emissions, and a plurality of angle of arrival sensors. Each sensor comprises one or more optical elements and a focal plane array (FPA), with the optical elements arranged to resolve the optical emissions into one or more linear patterns on the FPA. A processing system in communication with the sensors establishes the orientation and position of each of the optical emitters using the linear patterns. A headgear tracking system employs point source emitters on a piece of headgear, with front and rear arrays of angle of arrival sensors located in an aircraft cockpit; a processing system in communication with the sensor arrays establishes an orientation and position for each of the optical emitters on the headgear.

Abstract: An optical tracking system comprises an array of point source emitters that output respective optical emissions, and a plurality of angle of arrival sensors. Each sensor comprises one or more optical elements and a focal plane array (FPA), with the optical elements arranged to resolve the optical emissions into one or more linear patterns on the FPA. A processing system in communication with the sensors establishes the orientation and position of each of the optical emitters using the linear patterns. A headgear tracking system employs point source emitters on a piece of headgear, with front and rear arrays of angle of arrival sensors located in an aircraft cockpit; a processing system in communication with the sensor arrays establishes an orientation and position for each of the optical emitters on the headgear.

Abstract: A segmented, rigid-rod aromatic polyimide mixed with a UV curable acrylate photopolymer material comprises an alignment layer for aligning nematic polymeric liquid crystal compensator films. The material may also provide an out-of-plane retardation. The segmented, rigid-rod aromatic polyimide-based UV curable acrylate alignment layer, when applied in appropriate thickness, functions as a negative uniaxial C-plate compensator and causes alignment of the nematic liquid crystal molecules. The combination of the retardation provided by the alignment layer and the compensator film deposited on it provides a significant improvement in the contrast and color stability of liquid crystal displays (LCDs) at large viewing angles.

Abstract: An anisotropic cross-linked PVA alignment layer for aligning nematic polymeric liquid crystal compensator films, which also provides an out-of-plane retardation. The cross-linked PVA alignment layer, when applied in sufficient thickness functions as both a negative uniaxial C-plate and causes alignment of the nematic liquid crystal molecules. The combination of the retardation provided by the alignment layer and the compensator film deposited on it provides a significant improvement in the contrast and color stability of liquid crystal displays (LCDs) at large viewing angles in which they are used.

Abstract: A spectral imager includes an elongate light propagation medium that receives light at one end, has graded average spectral absorption properties in the elongate direction, and spectral detectors distributed in the elongate direction. The spectral absorption properties of the medium can be graded in both elongate and transverse directions. Both linear and two-dimensional arrays can be formed, enabling simultaneous hyperspectral detection.

Abstract: A normally white liquid crystal display includes polarizer and analyzer layers having perpendicular absorbing axes. A liquid crystal layer is disposed between the polarizer layer and the analyzer layer, with its director exhibiting an azimuthal twist through the layer. First and second electrodes are proximate to first and second major surfaces of the liquid crystal layer. A first negatively birefringent compensator layer, oriented with its optical axis substantially parallel to the average direction of the optical axis within a central, nominally homeotropic region of the liquid crystal layer in its driven state, is disposed between the polarizer layer and the liquid crystal layer. A second negatively birefringent compensator layer, with a birefringence substantially the same as the birefringence of the first compensator layer and oriented with its optical axis substantially parallel to the optical axis of the first compensator layer, is disposed between the analyzer layer and the liquid crystal layer.

Abstract: A method to fabricate a photo-patterned organic compensator for liquid crystal displays, and the resulting compensator structure, are described. One illustrative fabrication method comprise: (1) depositing a thin film of polymerizable liquid crystal material onto one of a display's substrates; (2) orienting the liquid crystal material's director to a specified direction; (3) polymerizing the deposited thin film through an aperture mask; (4) removing the aperture mask; and (5) curing/annealing the thin film layer to yield a planar structure having substantially birefringent and isotropic regions. Complete pixelated compensators may be created by layering two or more such two-region thin films.

Abstract: An optical device for transforming light and an associated liquid crystal display is disclosed. The device includes a layer of cholesteric material of the type which transmits light having a first circular helicity and reflects light having a second circular helicity. A quarter-wave plate positioned on a first side of the layer of cholesteric material converts the transmitted light having the first circular helicity into linearly polarized light. A compensator including a positively birefringent C-plate layer is disposed between the layer of cholesteric material and the quarter-wave plate. The compensator reduces undesirable phase effects in the transmitted light introduced by the layer of cholesteric material. The disclosed LCD employs the optical device to increase backlighting efficiency while improving field of view and chromaticity of the display.

Abstract: An optical O-plate compensation device, in accordance with the invention, uses an inorganic thin film which is grown by physical vapor deposition at oblique incidence. The resulting thin film exhibits a biaxial form birefringence and performs, in a liquid crystal display (LCD), in a similar manner to uniaxial films with its extraordinary axis oriented obliquely at about 45.degree. with respect to the surface of the film. The invention makes possible a significant improvement in the gray scale properties and contrast ratios of liquid crystal displays (LCDs) over a wide range of viewing angles.

Abstract: A twisted/splayed O-plate compensation device, in accordance with the invention, is comprised of an organic liquid crystal polymer thin film and possibly one or more other birefringent layers. The O-plate thin film is a birefringent medium with its optical symmetry axis, on average, oriented obliquely with the surface of the film. Within this constraint, the direction of the material's optical symmetry axis is allowed to vary continuously along the axis normal to the film surface. Such films may be fabricated by applying thin layers of chiral doped nematic or semectic liquid crystal monomer solutions in inert solvents to transparent substrates. The carrier solvents are then evaporated and the monomers polymerized by UV irradiation. Compensation devices may also be comprised of multiple layers of twisted/splayed O-plate material in conjunction with A-plates, C-plates, and simple O-plates. Fabrication techniques for twisted/splayed O-plates are described.

Abstract: A novel normally-white dual-domain twisted nematic liquid crystal display exhibits dramatically improved contrast and gray scale linearity stability over a wide range of viewing angles as compared to conventional dual-domain twisted nematic displays. The display incorporates one or more pixelated compensator layers internal to the liquid crystal cell. A pixelated compensator layer has a pattern wherein the orientation or retardation of the compensator layer varies according to the tilt domain structure of the display's liquid crystal material. Such a pixelated compensator layer allows optimal compensation for each of the differently oriented liquid crystal tilt domains. The pixelated compensator layer(s), and possibly one or more non-pixelated compensator layers, may be deposited on either a display's active matrix substrate or its (passive) color filter substrate, or a combination thereof.

Abstract: A liquid crystal display for viewing at various angles with respect to a normal axis perpendicular to the display includes a polarizer layer having an absorbing axis, an analyzer layer having an absorbing axis substantially perpendicular to the absorbing axis of the polarizer layer, a liquid crystal layer disposed between the polarizer layer and the analyzer layer and having a director exhibiting an azimuthal twist through the layer with respect to the normal axis, a first electrode proximate to a first major surface of the liquid crystal layer, a second electrode proximate to a second major surface of the liquid crystal layer, the first and second electrodes being adapted to apply a voltage across the liquid crystal layer when the electrodes are connected to a source of electrical potential, and a compensator, including a positively birefringent O-plate compensator layer disposed between the polarizer layer and the analyzer layer with its principal symmetry axis oriented at a substantially oblique angle with

Abstract: The multicolor focal plane array of this invention detects and distinguishes between incoming electromagnetic radiation within a first band of wavelengths and incoming electromagnetic radiation within a second band of wavelengths which includes the first wavelength band. The array includes a substrate and a two dimensional array of detectors disposed on the substrate and responsive to electromagnetic radiation within a predetermined range of wavelengths including the first and second wavelength bands. A first thin film filter is disposed on the substrate and interposed between the incoming radiation and a subset of the detectors in the array to prevent radiation outside of the first wavlength band from reaching the detectors. A second thin film filter is disposed on the substrate and interposed between the incoming radiation and all of the detectors in the array to prevent radiation outside of the second wavelength band from reaching the detectors in the subset.

Abstract: A rugate type thin film optical interference filter is disclosed. Rugate filters are gradient-index optical filters in which the index of refraction of the film varies sinusoidally with thickness. Gradient-index filters vary the index of refraction continuously with thickness, instead of discontinuously as in, for example, quarter-wave stacks of alternating discrete layers of high and low refractive index. Rugate filters are generally used as narrow bandwidth blocking, or rejection, filters in which the specific wavelength of light reflected, or blocked, is directly proportional to the period of a simple sine wave that describes the refractive index profile of the film. Multiple-line rejection filters, in which more than one wavelength, or line, is reflected, are made by superimposing individual sine waves in parallel. The present invention provides a more easily made rugate filter by reducing the maximum required peak-to-peak refractive index modulation within the film.

Abstract: Disclosed is an apparatus for removing electromagnetic energy at a wavelength .lambda. from a beam of electromagnetic energy. Included is an electro-optically tunable Fabry-Perot filter, with an electro-optic crystal having parallel incident and exit surfaces, a first transparent electrode on the incident surface, a second transparent electrode on the exit surface, an incident reflecting layer, and an exit reflecting layer. A detector produces an electrical signal in response to the electromagnetic energy transmitted by the filter. A lock-in amplifier receives the electrical signal and outputs to a control amplifier which also receives as an input a source of alternating current. A high voltage amplifier receives the output of the control amplifier and applies its output across the electro-optic crystal.