Abstract: The present invention is directed to liquid crystal diffraction gratings with electrically controlled periodicity. An electrical field is applied to liquid crystal device wherein the liquid crystals align to form a diffraction grating. The period of the diffraction grating is varied by changing the applied electrical field. The diffraction grating therefore has a period that can be varied by an electrical field.

Abstract: A system for the detection of ligands comprising at least one receptor and an amplification mechanism coupled to the receptor wherein an amplified signal is produced as a result of receptor binding a ligand. Examples of suitable amplification mechanisms include antibody-embedded liquid crystalline materials; use of alpha-2-macroglobulin to encage an enzyme, whereby the enzyme is separated from its substrate by an receptor; and a receptor engineered to inhibit the active of site of an enzyme only in the absence of a ligand. Also provided are methods for the automatic detection of ligands.

Abstract: A flat-panel liquid crystal display. The display includes a flat sheet of bistable chiral nematic liquid crystal material activated by a drive circuit that individually controls the display state of multiple picture elements. The driver circuitry activates the liquid crystal domains with various drive schemes which have any number of different phases to attain various addressing sequence times. At the end of each drive scheme, the texture of the liquid crystal material is allowed to provide either focal conic or twisted planar end states across the two-dimensional array of picture elements. Each drive scheme employs at least a preparation phase and a selection phase to predispose the liquid crystal material to one of the end states.

Abstract: A liquid crystalline light modulating pixel includes first and second cell wall structures and nematic liquid crystal disposed therebetween. The first and second cell wall structures cooperate with the liquid crystal to form four liquid crystal domains within the pixel. The liquid crystal in each of the domains exhibits a twisted nematic liquid crystal structure and the orientation of the liquid crystal director of the liquid crystal adjacent one of the cell wall structures in at least two domains is different.

Abstract: A liquid crystal display device including a polyimide alignment layer, having a bistable liquid crystal material and a polymer stabilizer in an amount effective to stabilize the liquid crystal, preferably about 2 weight percent, associated with the liquid crystal material, the liquid crystal having a low pretilt angle, to eliminate stripe tendency and to increase hysteresis. The device has a low driving voltage, low power consumption and fast switching.

Abstract: A new liquid crystalline light modulating cell and material are characterized by liquid crystalline light modulating material of liquid crystal and polymer, the liquid crystal being a chiral nematic liquid crystal having positive dielectric anisotropy and including chiral material in an amount effective to form focal conic and twisted planar textures, the polymer being distributed in phase separated domains in the liquid crystal cell in an amount that permits the liquid crystal to change textures upon the application of a field and ruggedizes the structure. In still another embodiment, the material exhibits stability at zero field in a colored, light reflecting state, a light scattering state and multiple stable reflecting state therebetween, as well as being optically clear in the presence of a field. In yet another embodiment, the application of mechanical force to the cell changes the material from an optically clear state to a light reflecting state.

Abstract: Polymer/cholesteric liquid crystal dispersions are provided in which the liquid crystal phase separated from the polymer matrix to form droplets. The cholesteric liquid crystals were positive dielectric anisotropic. At a zero field condition, the liquid crystal in the droplets was bistable, that is, the liquid crystal can be in either the reflecting planar state or the scattering focal conic state. When the liquid crystal 101 was in the planar texture, the helical axis of the liquid crystal was more or less perpendicular to the cell surface; colored light 105 was Bragg reflected. When the liquid crystal 101 was in the focal conic texture, the helical axis was more or less parallel to the cell surface, incident light was scattering 106 in the forward direction.

Abstract: A ferroelectric liquid crystal cell with a monochevron structure includes a pair of opposed substrates each having an alignment layer. The alignment layer includes a conventional polymer and a ferroelectric copolymer. A ferroelectric liquid crystal material is disposed between the pair of opposed substrates and interacts with the alignment layers which force the ferroelectric liquid crystal into a monochevron structure because of the interaction between the ferroelectric liquid crystal material polarization and polarization of the alignment layers.

Abstract: A light modulating cell comprises a pair of substrates, alignment layers disposed on at least one of the substrates and a solution of polymerizable prepolymer and low molecular weight organic material disposed between the pair of substrates. The solution is phase separated and forms a layer of polymeric material and a layer of organic material between the two substrates. An external force may then be applied across the substrates to alter the optical appearance of the layer of organic material from one state to another. A photo-sensitive layer may also be provided in the cell.

Abstract: A non-contacting method of forming an alignment layer on a substrate used in liquid crystal displays which includes the steps of cleaning a substrate surface, disposing a solution having a prepolymer, such as polyamic acid or a resin and a curing agent, and solvent on the substrate surface, evaporating the solvent, and positioning an ultraviolet light source proximally near the substrate surface. A linear polarizer is positioned between the ultraviolet light source and the substrate surface. Ultraviolet light is projected through the polarizer onto the substrate surface to simultaneously molecularly align the polymer segments as the prepolymer is polymerized to form an alignment layer on the substrate. Adjusting the direction of polarization and the angle of incidence of the ultraviolet light source allows for generation of an alignment layer with a corresponding pre-tilt angle.

Abstract: A method for forming walls (8) between substrates (11, 12) in a liquid crystal cell (10) includes the step of forming a cell with a liquid crystal-monomer mixture (50). The cell (10) is then exposed to ultraviolet light (70) causing the monomer to be selectively polymerized to form walls (8) between substrates (11, 12) of the cell. The monomer is selectively polymerized by applying an electric field across the cell through a patterned conductive coating (31, 32) on each substrate (11, 12) to separate the dispersed monomer to the low field, interpixel regions (72). The cell (10) is then exposed to ultraviolet light (70) to polymerize the separated monomer to form the walls (8) in the low field regions (72).

Abstract: A liquid crystal shutter and a drive waveform for controlling the same is presented by this invention. The liquid crystal shutter includes two distinct layers of liquid crystal material where one layer has a right hand twist sense and the other layer has a left hand twist sense. An electric field is selectively applied to the layers of liquid crystal material which have dual frequency properties. Accordingly, when a low frequency is applied to the liquid crystal materials they exhibit a positive dielectric anisotropy and a homeotropic texture which is substantially transparent. When a high frequency electric field is applied to the liquid crystal materials they exhibit a negative dielectric anisotropy and a planar texture which is substantially reflective. The liquid crystal material may be selected to selectively reflect predetermined spectrums of light.

Abstract: A new liquid crystalline light modulating cell and material are characterized by liquid crystalline light modulating material of liquid crystal and polymer, the liquid crystal being a chiral nematic liquid crystal having positive dielectric anisotropy and including chiral material in an amount effective to form focal conic and twisted planar textures, the polymer being distributed in phase separated domains in the liquid crystal cell in an amount that stabilizes the focal conic and twisted planar textures in the absence of a field and permits the liquid crystal to change textures upon the application of a field. In one embodiment, the material is light scattering in a field-OFF condition and optically clear in a field-ON condition, while in another embodiment, the material is optically clear in a field-OFF condition and light scattering in a field-ON condition.

Abstract: A liquid crystalline light modulating pixel includes first and second cell wall structures and nematic liquid crystal within a UV cured polymer network disposed therebetween. The first and second cell wall structures cooperate with the liquid crystal to form four liquid crystal domains within the pixel. The liquid crystal in each of the domains exhibits a twisted nematic liquid crystal structure and the orientation of the liquid crystal director of the liquid crystal adjacent one of the cell wall structures in at least two domains is different. The polymer network stabilizes the four domain structure at both high field and zero field conditions.

Abstract: A reflective liquid crystalline diffractive light valve for use in a diffractive projection system. The liquid crystal cell includes a transparent substrate and a reflective substrate treated to provide alternating stripes which cooperate with the liquid crystal to form liquid crystal domains extending across the thickness of the cell that will produce an appropriate phase difference in light reflected by the cell, irrespective of the polarization of incident light. The techniques embodied in the present invention are applicable to the creation of electrically controllable diffractive optical elements for ray optic, integrated optic or fiber optic utilization operated in either transmission or reflection. Diffractive patterns may be lithographically, holographically or interferometrically generated.

Abstract: A flat-panel liquid crystal display. The display includes a flat sheet of bistable chiral nematic liquid crystal material activated by a drive circuit that individually controls the display state of multiple picture elements at a refresh rate 1000 scan lines per second. The driver circuitry activates the liquid crystal domains into homeotropic states over a relatively long activation period and then, during a short (.about.1 msec.) selection period, either keeps the domains in a homeotropic state or initiate a transition to the transient twisted planar state. The drivers then activate the domains in an evolution phase to provide either focal conic or twisted planar end states across the two-dimensional array of picture elements.

Abstract: Thin films of 2H .alpha.-silicon carbide are produced by pulsed laser ablation.

Abstract: A new liquid crystalline light modulating cell and material are characterized by liquid crystalline light modulating material of liquid crystal and polymer, the liquid crystal being a chiral nematic liquid crystal having positive dielectric anisotropy and including chiral material in an amount effective to form focal conic and twisted planar textures, the polymer being distributed in phase separated domains in the liquid crystal cell in an amount that stabilizes the focal conic and twisted planar textures in the absence of a field and permits the liquid crystal to change textures upon the application of a field. In one embodiment, the material is light scattering in a field-OFF condition and optically clear in a field-ON condition, while in another embodiment, the material is optically clear in a field-OFF condition and light scattering in a field-ON condition.

Abstract: A new liquid crystalline light modulating cell and material are characterized by liquid crystalline light modulating material of liquid crystal and polymer, the liquid crystal being a chiral nematic liquid crystal having positive dielectric anisotropy and including chiral material in an amount effective to form focal conic and twisted planar textures, the polymer being distributed in phase separated domains in the liquid crystal cell in an amount that stabilizes the focal conic and twisted planar textures in the absence of a field and permits the liquid crystal to change textures upon the application of a field. In one embodiment, the material is light scattering in a field-OFF condition and optically clear in a field-ON condition, while in another embodiment, the material is optically clear in a field-OFF condition and light scattering in a field-ON condition.

Abstract: An improvement in a light modulating chiral nematic liquid crystal adapted to form focal conic and twisted planar textures and a liquid crystal device employing such a material, the improvement wherein the liquid crystal material includes a plurality of essentially distinct regions within which the liquid crystal has different pitch lengths, whereby the liquid crystal can be made to reflect different wavelengths of light in different regions. The regions are created by including in the chiral nematic liquid crystal composition, a chiral material adapted to change its chirality upon photo-irradiation, in an amount effective to change the pitch length of the liquid crystal composition upon photo-irradiation. By exposing different regions of the material to increasing amounts of photo-irradiation, the pitch length of each region can be selectively tuned to reflect light of a different wavelength.