Abstract: Devices and methods relating to a vertical alignment layer with a preferred azimuthal angle for a liquid crystal device are provided. A method of preparation comprises preparing an alignment layer mixture of a polymeric vertical alignment material, an azo compound photo-aligned material, a reactive mesogen or liquid crystal monomer, a polyamic acid, a photo- or thermal-initiator, and an organic solvent, coating the alignment layer mixture onto a substrate, and irradiating the coated substrate with UV or blue light at an oblique angle.

Abstract: Devices and methods relating to a vertical alignment layer with a preferred azimuthal angle for a liquid crystal device are provided. A method of preparation comprises preparing an alignment layer mixture of a polymeric vertical alignment material, an azo compound photo-aligned material, a reactive mesogen or liquid crystal monomer, a polyamic acid, a photo- or thermal-initiator, and an organic solvent, coating the alignment layer mixture onto a substrate, and irradiating the coated substrate with UV or blue light at an oblique angle.

Abstract: A polymeric thread includes a transparent polymeric substrate; a first patterned layer with a miniature pattern disposed at a side of the polymeric substrate; and a first florescent layer containing a florescent taggant disposed at a side of the patterned layer that is facing away from the polymeric substrate. An authentication tag utilizing the polymeric thread and a method for making the polymeric thread are also provided.

Abstract: A polymeric thread includes a transparent polymeric substrate; a first patterned layer with a miniature pattern disposed at a side of the polymeric substrate; and a first florescent layer containing a florescent taggant disposed at a side of the patterned layer that is facing away from the polymeric substrate. An authentication tag utilizing the polymeric thread and a method for making the polymeric thread are also provided.

Abstract: An object authentication system for authenticating an object includes a taggant material applied to the object; a database storing data related to the excitation-emission properties of the taggant material and to an identity of the object; and an authentication reader. The authentication reader includes an excitation source for emitting light for exciting the taggant material, an emission detection device for detecting light emission of the excited taggant material, and a processing unit for analyzing the detected light emission, comparing the detected light emission profile with data stored in the database, and thereby verifying the identity of the object. The taggant material includes a fluorescent material and the taggant material is applied to the object by being mixed into the raw material of the object, being integrated with a portion of the object, or being attached to the object by an adhesive material. A method for authenticating an object is also provided.

Abstract: There is provided a reflective liquid crystal cell formed of a liquid crystal material disposed between first and second substrates. The first substrate is optically transparent and is formed with a coating of optically transparent and electrically conductive material on the side facing the liquid crystal material. The second substrate is formed with a plurality of coatings on the side facing the liquid crystal material. These coatings include in sequence a layer of metallic reflective material, a layer of electrically insulating material, a layer of na optically transparent and conductive material and a liquid crystal alignment layer.

Abstract: The present invention provides the conditions for new bistable twisted nematic liquid crystal displays, in particular the necessary twist angles, liquid crystal retardation values, input and output polarizer angles, for both transmissive and reflective liquid crystal displays.

Abstract: Three measuring methods and apparatus for determining the twist angle (&phgr;) and retardation value (d&Dgr;n) of any twisted nematic liquid crystal (LC) cell are disclosed. These methods make use of a monochromatic light source such as a laser beam. Twist angle and retardation values an be obtained by data fitting using data obtained by adjusting only the polarizes and the LC cell orientation. No retardation wave-plate is needed.

Abstract: There is provided a reflective liquid crystal cell formed of a liquid crystal material disposed between first and second substrates. The first substrate is optically transparent and is formed with a coating of optically transparent and electrically conductive material on the side facing the liquid crystal material. The second substrate is formed with a plurality of coatings on the side facing the liquid crystal material. These coatings include in sequence a layer of metallic reflective material, a layer of electrically insulating material, a layer of na optically transparent and conductive material and a liquid crystal alignment layer.

Abstract: A liquid crystal display is described in which the need for a conventional output polarizer is eliminated and the display comprises only a liquid crystal cell, a single input polarizer, a reflector placed behind the cell, and a retardation film placed between the reflector and the cell. A Jones matrix simulation approach is used in order to obtain the parameters corresponding to solution spaces for the above design and several combinations are disclosed that give good results.

Abstract: The present invention relates to methods and apparatus for measuring the optical properties, eg twist angle, cell gap, input director, of a transmissive or reflective liquid crystal cell. For a transmissive liquid crystal cell the cell is placed between a polarizer and an analyzer and the transmission spectrum observed while rotating the analyzer until zero transmission is obtained at at least one wavelength. The twist angle and the surface rubbing orientations of the liquid crystal cell are determined by the relative angle between the polarizer and the analyzer while the cell gap is determined from the calculated retardation value d.DELTA.n with known .DELTA.n. For reflective cells cell gap is determined based on a knowledge of twist angle and is accomplished by observing zero reflection wavelengths from a reflective cell with the polarizer and analyzer in cross-orientation.