Abstract: An electrooptical light modulating device includes a liquid crystalline material disposed between first and second opposing cell wall structures and comprising liquid crystal of positive dielectric anisotropy. The first cell wall structure is treated with a first aligning material to homeotropically align liquid crystal molecules of the material and the second cell wall structure is treated with a second aligning material that is different from the first aligning material to homeotropically align liquid crystal molecules of the material, whereby the liquid crystal exhibits a unipolar electrooptic effect in the presence of an electric field.

Abstract: Disclosed is a class of light modulating materials comprising microdomains of ferroelectric smectic liquid crystal dispersed in a light-transmissive polymer medium. The microdomains are formed by phase separation of the liquid crystal from solution with the polymer as the polymer is solidified. The switching of the liquid crystal may be either monostable or multistable (e.g., bistable), depending on the liquid crystal and polymer. The material modulates light in either a scattering-transmissive mode or a birefringence mode. Materials operating in the scattering-transmissive mode do not require polarizers, Advantages of the materials include switching times down to the order of microseconds or less, multistable optical states, wide viewing angles and high contrast.

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

Abstract: An oriented ferroelectric liquid crystal in the chiral smectic C phase with the smectic planes normal to bounding plates of a cell is interspersed with polymer which stabilizes and freezes the arrangement of the liquid crystal. The polymer which stabilizes the liquid crystal is formed by a method which includes introducing a mixture of a monomer and a ferroelectric liquid crystal between cell walls when the liquid crystal is in the isotropic phase, cooling the liquid crystal to a chiral nematic or smectic phase, and polymerizing the monomer. The cooling of the mixture can be done in the presence of a magnetic or electric field.

Abstract: A light modulating reflective cell comprising a polymer-free chiral nematic liquid crystalline light modulating material is disclosed. The cell includes nematic liquid crystal having positive dielectric anisotropy and chiral material in an amount effective to form focal conic and twisted planar textures. The chiral material has a pitch length effective to reflect light in the visible spectrum, wherein the focal conic and twisted planar textures are stable in the absence of a field and the liquid crystal material is capable of changing textures upon the application of a field.

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 oriented ferroelectric liquid crystal in the chiral smectic C phase with the smectic planes normal to bounding plates of a cell is interspersed with polymer which stabilizes and freezes the arrangement of the liquid crystal.

Abstract: A method of selectively adjusting the intensity of reflection to obtain stable grey scale reflectance of colored light from a light modulating chiral nematic liquid crystal material is disclosed. The method comprises subjecting the material to an electric field pulse of sufficient duration and voltage to cause a first proportion of the chiral nematic material to exhibit a first optical state and a second proportion of the chiral nematic material to exhibit a second optical state, whereby the material will continuously reflect a selected intensity between a maximum and minimum that is proportional to the amount of the material in the first optical state.

Abstract: A liquid crystalline paste material is formed by polymerization of a solution containing a mesogenic solvent and monomeric material in bulk. The paste provides an improved method of preparing thin electrically addressable light modulating films by coating the paste onto a suitable substrate.

Abstract: A method for promoting uniform "bookshelf" textures in light modulators using smectic C* liquid crystal is disclosed. The method comprises the steps of confining smectic C* phase liquid crystal between parallel substrates having inner surfaces treated to promote homeotropic alignment of the liquid crystal near the inner surfaces, generating an electric field normal to the inner surfaces of the substrates and biasing the liquid crystal in a direction parallel to the inner surfaces of the substrates to induce the formation of smectic layers normal to the inner surfaces of the substrate. For example, the perturbation may be carried out by supplying a cyclic shear to one of the substrates or by means of a magnetic field parallel to the substrates. Reversal of the polarity of the electric field switches the material between two stable bookshelf textures.

Abstract: The invention provides an improvement in light modulating devices employing birefringent liquid crystal interspersed in isotropic polymer. A polarizer disposed on a surface of the liquid crystal device produces haze-free viewing for all viewing angles in the plane orthogonal to the polarization direction of the light passed by the polarizer.

Abstract: A light modulating apparatus comprising a liquid crystal light modulating material confined between substrates, elongated electrically-conductive paths supported on opposite sides of the light modulating material by the substrates and a pair of gating systems for supplying voltage pulses to the electrically conductive paths for addressing the light modulating material is disclosed. The light modulating material includes polydomains of polymer network dispersed in a chiral nematic liquid crystal having positive dielectric anisotropy. This material is confined by the substrates between inner surfaces treated to promote homogeneous alignment of the liquid crystal near the inner surfaces. The apparatus provides energy efficient passive control of a bistable light modulating material.

Abstract: A haze-free light modulating polymer dispersed liquid crystal (PDLC) material is disclosed which comprises a polymer which is birefringent and possesses anisotropic optical properties similar to those of the dispersed liquid crystal such that the PDLC material in its transparent state exhibits a refractive index that is matched for all directions of incident light providing for an optically clear, scatter-free film for all angles of view. Electrooptic light shutters are possible from this material which are transparent in the field OFF-state and opaque in the field ON-state or vice versa, depending upon the liquid crystal phase structure and configuration of the light shutter device.

Abstract: An infrared modulating material comprising a first infrared transmissive phase dispersed in a second infrared transmissive phase. One of the phases comprises a liquid crystal phase and the other comprises a medium phase. The liquid crystal phase has an ordinary index of refraction for infrared radiation matched to an index of refraction of the medium for infrared radiation so that infrared radiation is scattered by the material in the absence of an external field and transmitted in the presence of an external field. In addition, the dispersed first phase has a feature size matched to a range of wavelengths of infrared radiation to be modulated so as to enhance the scattering of the radiation by the material in the absence of an applied field.

Abstract: Novel mesogenic amine curing agent for reactive monomers, such as epoxy resins and diisocyanates, comprises a mesogenic moiety, a primary amine, and a flexible alkyl spacer connected between the mesogenic moiety and the primary amine and wherein the alkyl spacer is a saturated, linear alkyl group having from about one to about twenty carbon atoms. Novel mesogenic amine has the formula: ##STR1## where M is --O--, ##STR2## or --CH.sub.2 --, where R is --NO.sub.2 or --CN, andwhere x is 1 to 20.Novel mesogenic amine has a labile group subject to cross-linking and the formula: ##STR3## where K is ##STR4## where L is ##STR5## where M is --o--, ##STR6## or --CH.sub.2 --, where Z is cinnamate, an alkene having from one to ten carbons, an isocyanate, an alkoxy, or an alcohol having from one to ten carbons,where T is a cyano, a nitro or an alkyl group having from about one to ten carbons, andwhere X is 1 to 20.

Abstract: The invention provides a low loss liquid crystal modulator for coloring and shaping a light beam wherein liquid crystal light modulators provide continuous variation in color and intensity output by controlled scattering; the liquid crystal light modulators comprise addressable sheets of light-wave-length size liquid crystal occlusious in a transparent matrix; the modulators employ nematic liquid crystal exhibiting positive dielectric anisotropy; the modulator is employed in varying and coloring output beams to allow for colored data or video transmission; images produced may vary in time as is required for, e.g., color television; the modulator is employed in color projectors for both data and video projection, for color printing, and for colored stage illumination. Low loss transmission of the modulators provides for bright images which can be viewed under high ambient illumination.

Abstract: An extended temperature range polymer dispersed liquid crystal light shutter electrically switchable between a transmissive and an opaque state over a working temperature range of about -40.degree. C. to about 100.degree. C. The shutter includes a polymer-dispersed liquid crystalline (PDLC) material comprising a fairly highly cross-linked transparent matrix having phase-separated microdroplets of liquid crystal dispersed therein, the liquid crystal existing in a supercooled liquid crystalline state at low temperatures. Such light shutters are employed in various windows and electrooptic displays, wherever it is desirable to be able to adjust visible or transparency and regardless of temperature extremes.

Abstract: A haze-free light modulating polymer dispersed liquid crystal (PDLC) material is disclosed which comprises a polymer matrix which is birefringent and possesses anisotropic optical properties similar to those of the dispersed liquid crystal microdroplets such that the PDLC material in its transparent state exhibits a refractive index that is matched for all directions of incident light providing for an optically clear, scatter-free film for all angles of view. Electrooptic light shutters are possible from this material which are transparent in the field OFF-state and opaque in the field ON-state or vice versa, depending upon the microdroplet structure and configuration of the light shutter device.

Abstract: A light modulating material comprising phase-separated microdroplets of liquid crystal in a light transmissive, synthetic resin matrix wherein the index of refraction n.sub.p of the matrix is matched or mismatched to an index of refraction N.sub.o of the liquid crystal optical axis of the microdroplets so that when the microdroplet director is aligned relative to a surface of the material, maximum transmission of light occurs at a selected oblique angle relative to the surface of the material or at a selected narrow angle about the perpendicular to the surface of the material. Such matching or mismatching of indices of refraction may be accompanied by phase separation in an external magnetic or electric field, or by shaping the liquid crystal microdroplet into an ovoid or the like during or after phase separation to align the microdroplet directors thereby endowing the material with a permanent and movable viewing angle.

Abstract: A light modulating material consisting of droplets of liquid crystal in a clear or light transmitting, flexible plastic sheet or film, such as a cured epoxy. The light modulating material is prepared by dissolving liquid crystal in an uncured resin and then curing the resin so that droplets of liquid crystal spontaneously form and are uniformly dispersed throughout the sheet or film. The new material shows a reversible, high contrast optical response from an opaque scattering mode to a clear light transmission mode when either the temperature of the material is changed to transform the liquid crystal into the isotropic phase or an electric field is applied across the material. The material is optically responsive to strain, whereby under tension it acts to polarize incident light. Curing the material in the presence of an applied field also causes it to act as an electrically addressable polarizer.