摘要:
This invention provides achromatic compound retarders, achromatic polarization switches, and achromatic shutters using the liquid crystal compound retarders. It further provides achromatic variable retardance smectic and nematic liquid crystal retarders. The achromatic compound retarders according to the invention are used to create achromatic inverters for display applications. The display comprises one or more retarders having in-plane retardance and in-plane orientation, at least one of the retarders being an actively controlled liquid crystal retarder, and a ferroelectric liquid crystal display, wherein the one or more retarders work in combination with the ferroelectric liquid crystal display to provide four states of brightness.
摘要:
A color filter device for controlling the color of light output by an illumination device or for controlling the color of light passing through a window includes at least a retarder and a polarization analyzer. The device may also include an input polarizer. The device may further include an electrically controllable modulator and an output retarder for selectively controlling the spectrum of light output by the device. A color filter device embodying the invention enables rapid and effective control over the spectrum and amplitude of light passing through the filter to achieve desired effects. A device embodying the invention could be an indicator light, an illumination device, a diagnostic testing device, a transmissive window, or any other type of device where rapid and effective control of a spectrum of light is desired.
摘要:
This invention provides split-element liquid crystal polarization interference filters in wide-field, bandpass, cut-on, cut-off and notch filter embodiments. The split-element filters of this invention comprise a polarization interference stage defined by a pair of polarizers. Disposed within the stage are a center retarder, and first and a second split-element retarder, the split-element retarders having equal retardances and positioned in series with and on either side of the center retarder. The retarders can be liquid crystal variable retarders or can be fixed retarders used in combination with liquid crystal retarders. Double split-element filters in passive and tunable embodiments are provided comprising, within a polarization interference stage, a center retarder, an inside pair of split-element retarders and an outside pair of split-element retarders.
摘要:
A retarder stack for preconditioning at least partially polarized light for input to a modulator includes a first retarder and the second retarder. The first retarder has a first retardance and a first orientation with respect to the partially polarized light and the second retarder has a second retardance and a second orientation with respect to the partially polarized light. The first retarder and second retarder are oriented with respect to each other and the first retardance and the second retardance are selected such that the light output from the second retarder includes a first portion of light and a second portion of light which, if input to a modulator, would be modulated differently. Hence, the retarder stack can be used to precondition light for input to a modulator such as an electro-optic, magneto-optic or other type of modulator.
摘要:
This invention provides achromatic liquid crystal compound retarders, achromatic polarization switches, and achromatic shutters using the liquid crystal compound retarders. It further provides achromatic variable retardance smectic liquid crystal retarders. The compound retarder of this invention comprises a central liquid crystal retarder unit and two external passive retarders positioned in series with and on either side of the liquid crystal retarder unit. The liquid crystal retarder unit comprises either (1) a rotatable smectic liquid crystal half-wave retarder or (2) first and second liquid crystal variable retarders having retardance switchable between zero and half-wave. The external passive retarders are equal in retardance and orientation to each other. Design equations determine the retardance of the external elements and their orientation relative to the central retarder to obtain a particular achromatic retardance for the compound structure.
摘要:
This invention provides a phase modulator comprising an electro-optically rotatable smectic liquid crystal half-wave retarder in combination with a cholesteric liquid crystal circular polarizer. Rotation of the half-wave retarder varies the phase delay of the modulator. A polarizing interferometer is provided utilizing the phase modulator of this invention in combination with a second cholesteric circular polarizer and a linear polarizer. A tunable Fabry-Perot resonator which does not require ordinary mirrors is provided utilizing the phase modulator of this invention in combination with a second cholesteric circular polarizer.
摘要:
This invention provides a liquid crystal polarization handedness switch, and optical devices employing the handedness switch in conjunction with optical elements which are sensitive to the handedness of incident light. The handedness switch receives unpolarized light and converts it into circularly polarized light with switchable handedness. In combination with cholesteric circular polarizers, switchable color filters are provided. The color filters of this invention include the analogous x-y polarization switch combined with colored partial polarizers. The liquid crystals employed in the color filter of this invention can include SmC*, SmA*, antiferroelectric, DHF, achiral ferroelectric and twisted nematic liquid crystals.
摘要:
The present invention provides optical modulators which comprise aligned chiral smectic liquid crystal cells within an optical resonance cavity. The cavity configurations include symmetric and asymmetric Fabry-Perot etalons. The liquid crystal cells can be planar- or homeotropically-aligned and can be discrete state or analog cells. The device configurations of the present invention provide discrete or continuous optical modulation of the phase, intensity, and wavelength of elliptically polarized light, without requiring polarization analyzers. The modulators are optically or electronically addressable in single pixels or arrays of multiple pixels. Certain homeotropically-aligned cells are provided as an aspect of this invention, as are certain variable retarders comprised of planar-aligned cells in combination with birefringent elements.
摘要:
The present invention provides a high brightness color selective light modulator (CSLM) formed by apolarization modulator positioned between two retarder stacks. The modulator changes the apparent orientation of one retarder stack relative to the other so that, in a first switching state of the modulator the two retarder stacks cooperate in filtering the spectrum of input light, and in a second switching state the two retarder stacks complement each other, yielding a neutral transmission spectrum. Two or more CSLM stages can be used in series, each stage providing independent control of a primary color. One preferred embodiment eliminates internal polarizers between CSLM stages, thereby providing an additive common-path full-color display with only two neutral polarizers. Hybrid filters can be made using the CSLMs of this invention, in combination with other active or passive filters. The CSLMs of this invention can be used in many applications, particularly in the areas of recording and displaying color images. They can be arranged in a multi pixel array by pixelating the active elements, and can be implemented as color filter arrays, using patterned passive retarders rather than active polarization modulators.