摘要:
Liquid crystal photonic devices and microcavities filled with liquid crystal materials are becoming increasingly popular. These devices often present a challenge when it comes to creating a robust alignment layer in pre-assembled cells. Previous research on photo-definable alignment layers has shown that they have limited stability, particularly against subsequent light exposure. A method of infusing a dye into a microcavity to produce an effective photo-definable alignment layer is described, along with a method of utilizing a pre-polymer infused into the microcavity mixed with the liquid crystal to provide photostability. In this method, the polymer layer, formed under optical irradiation of liquid crystal cells, is effectively localized to a thin region near the substrate surface and thus provides a significant improvement in the photostability of the liquid crystal alignment. This versatile alignment layer method, which can be used in microcavities to displays, offers significant promise for new photonics applications.
摘要:
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.
摘要:
A state-of-polarization (SOP) control system (10) uses a SOP controller (28) that is responsive to a CPU (24) to perform endless and complete polarization signal detection for a fiber optic communication system. The SOP controller (28) comprises liquid crystal variable optical retarders (40, 42 and 44) that adjust the polarization state of local optical signal (36) in response to voltages provided by the CPU (24). The CPU (24) adjusts the voltage applied to the retarders (40, 42, and 44) separately in response to the magnitude of an interference signal (70), which corresponds to the degree to which the polarization of the local optical signal (36) and an input optical signal (12) are different.
摘要:
A field sequential color display system incorporates a color switch which includes a zero to half-wave optical retarder and pleochroic filters to provide an image with high color contrast and resolution over a broad range of display sizes. In a preferred embodiment, a liquid crystal cell which operates between two states of optical retardation comprises the variable retarder to provide a color switch with substantially reduced optical response times.
摘要:
A switchable color filter (11) includes three polarizing filters (12, 14, and 16) and two zero to substantially half-wave optical retarders (36 and 38) and is incorporated in a field sequential display system (10) to provide output states of light of three different colors to form an image in full color. Each one of four preferred embodiments (11, 11a, 11b, and 11c) of the switchable color filter provides the output states of three colors. The third and fourth preferred embodiments (11b and 11c) provide a fourth additional output state of, respectively, white light and light of a color which is a combination of two of the other output state colors. The optical retarders comprise nematic liquid crystal cells (100) having fast relaxation times to operate the display system at video rates.
摘要:
A color liquid crystal display (LCD) includes many ones of a color cell triad (150) of liquid crystal cells (80R, 80G, 80B) and a negative birefringence compensator plate (110). The color cell triads are positioned between a pair of linear polarizers (112, 114), and each color cell triad is in optical association with colored filters (152R, 152G, 152B). Each of the liquid crystal cells has a symmetrical director field (82, 82') that produces a symmetrical but nonuniform color viewing circle curve (100) from the liquid crystal cell. The negative birefringence plate restores the color viewing angle uniformity. When graphed on a polar plot, the measured light transmission percentage curves (120, 122, 124) characterizing the LCD are substantially concentric circles surrounding the optical axis (18) for all azimuthal angles (28) and viewing angles (24) up to 30 degrees. Thus, the color LCD provides a multi-color display having colors that are perceptibly uniform over a wide range of azimuthal and viewing angles.
摘要:
A switchable color filter (11) includes three polarizing filters (12, 14, and 16) and two zero to substantially half-wave optical retarders (36 and 38) and is incorporated in a field sequential display system (10) to provide output states of light of three different colors to form an image in full color. Each one of four preferred embodiments (11, 11a, 11b, and 11c) of the switchable color filter provides the output states of three colors. The third and fourth preferred embodiments (11b and 11c) provide a fourth additional output state of, respectively, white light and light of a color which is a combination of two of the other output state colors. The optical retarders comprise nematic liquid crystal cells (100) having fast relaxation times to operate the display system at video rates.
摘要:
A phase retarder comprises first and second π-cells or other tunable birefringent devices arranged optically in series. The phase retardation value of the phase retarder is a difference between the phase retardation values of the first and second π-cells. Driving circuitry drives the phase retarder to generate a target phase retardation value by: (1) prior to a relaxation period, biasing the π-cells to produce the target phase retardation value; (2) during the relaxation period, biasing the first π-cell at a constant bias value; and (3) during the relaxation period, lowering the bias value of the second π-cell continuously or stepwise to maintain the target phase retardation value for the phase retarder throughout the relaxation period. In some embodiments the operation (2) comprises applying zero bias to the first π-cell throughout the relaxation period. In some embodiments the operation (1) comprises applying a maximum operational bias to the second π-cell.
摘要:
A phase retarder comprises first and second π-cells or other tunable birefringent devices arranged optically in series. The phase retardation value of the phase retarder is a difference between the phase retardation values of the first and second π-cells. Driving circuitry drives the phase retarder to generate a target phase retardation value by: (1) prior to a relaxation period, biasing the π-cells to produce the target phase retardation value; (2) during the relaxation period, biasing the first π-cell at a constant bias value; and (3) during the relaxation period, lowering the bias value of the second π-cell continuously or stepwise to maintain the target phase retardation value for the phase retarder throughout the relaxation period. In some embodiments the operation (2) comprises applying zero bias to the first π-cell throughout the relaxation period. In some embodiments the operation (1) comprises applying a maximum operational bias to the second π-cell.
摘要:
A liquid crystal etalon includes a chiral nematic material contained in a liquid crystal cell having alignment surfaces configured to bias the chiral nematic material toward a twisted liquid crystal configuration with a twist less than 360°. Electrodes are arranged to apply an operative electrical bias to the liquid crystal cell. Mirrors disposed about the chiral nematic material define a resonant optical cavity. At a first electrical bias the etalon is transmissive for light of a first wavelength via a selected liquid crystal twist angle and cavity thickness at which different non-equal eigenmodes reach resonance conditions simultaneously. In a projector embodiment, a projection system with a field sequential image projection light source is coupled with the liquid crystal etalon, the etalon electrodes are patterned into pixels defining a display area, and the projector is operated in a field sequential illumination mode.