Patents by Inventor Kristina M. Johnson

Kristina M. Johnson has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5381253
    Abstract: 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.
    Type: Grant
    Filed: November 14, 1991
    Date of Patent: January 10, 1995
    Assignee: Board of Regents of University of Colorado
    Inventors: Gary D. Sharp, Kristina M. Johnson, Mark O. Freeman
  • Patent number: 5377026
    Abstract: This invention provides an electro-optic modulator which, in some embodiments, utilizes the linear electro-optic effect in liquid crystal materials. The liquid crystal modulator of this invention comprises a chiral smectic liquid crystal cell with electrodes to supply an electric field in a direction with a nonzero linear electro-optic coefficient, and means to suppress change in the tilt angle and azimuthal angle of the liquid crystal molecular directors. The response time of the linear electro-optic effect modulators of this invention is in the nanosecond range or faster. This modulator can be employed in Fabry-Perot or waveguide devices to provide increased modulation via multiple passes. This invention further provides for prism-coupling of light into or out of the waveguide structure whereby the modulator provides amplitude modulation, tunable filtering, or both.
    Type: Grant
    Filed: September 2, 1992
    Date of Patent: December 27, 1994
    Inventors: Jian-Yu Liu, Kristina M. Johnson, Michael G. Robinson
  • Patent number: 5361320
    Abstract: This invention provides a fiber waveguide with a liquid crystal core. The liquid crystals are aligned in layers with molecular directors approximately parallel to each other. An electric field can be applied to the liquid crystal core to provide linear and nonlinear optical modulation. Alone or in combination with polarizers, reflectors, and birefringent elements, the waveguide of this invention provides phase, polarization and intensity modulation, spectral filtering, and second harmonic generation.
    Type: Grant
    Filed: February 19, 1993
    Date of Patent: November 1, 1994
    Assignee: University of Colorado Foundation
    Inventors: Jian-Yu Liu, Kristina M. Johnson
  • Patent number: 5243455
    Abstract: Discretely and continuously tunable single and multiple-stage polarization interference filters employing chiral smectic liquid crystal cells as electronically rotatable retarders are provided. Discretely tunable filters of this invention include those which employ bistable surface-stabilized ferroelectric liquid crystal cells. Continuously tunable filters of this invention include those that employ chiral smectic A ferroelectric liquid crystal cells. Single stage filters include fixed birefringent elements in combination with chiral smectic liquid crystal cells and multiple stage filters can include only chiral smectic liquid crystal cells or can include chiral smectic liquid crystal cells in combination with fixed birefringent elements. Blocking filters useful for color generation and color displays are also provided. The FLC filters provided can be temporally multiplexed.
    Type: Grant
    Filed: May 15, 1992
    Date of Patent: September 7, 1993
    Assignee: The University of Colorado Foundation, Inc.
    Inventors: Kristina M. Johnson, Gary D. Sharp
  • Patent number: 5231521
    Abstract: The present invention provides optical polarization interference filters which employ chiral smectic liquid crystal (CSLC) cells as electronically rotatable retarders. The filters of the present invention are improved in that they are optimized for increased spectral discrimination, uniqueness of spectral outputs and efficient use of CSLC elements. The filters of the present invention include improved single and multiple stage filters. Improved discretely tunable and continuously tunable filters are provided. With respect to filters having one or more stages that contain a series of birefringent elements which are either fixed birefringent elements or active CSLC cells, this invention provides designs which optimize the number of pure spectral outputs which are unique. This optimization relates to the relative order of elements in a stage, the pattern of switching of the active CSLC cells, and the retardations of the CSLC cells in a stage.
    Type: Grant
    Filed: May 15, 1992
    Date of Patent: July 27, 1993
    Assignee: The University of Colorado Foundation, Inc.
    Inventors: Kristina M. Johnson, Gary D. Sharp
  • Patent number: 5132826
    Abstract: Discretely and continuously tunable filers emplying FLC cells are provided. Exemplary discretely tunable filters employ bistable smectic C* FLC cells. Exemplary continuously tunable filters employ smectic A* FLC cells. Single or multiple stage filters are provided. Blocking filters useful for color generation are also provided. The FLC filters provided can be temporally multiplexed.
    Type: Grant
    Filed: May 11, 1990
    Date of Patent: July 21, 1992
    Assignee: The University of Colorado Foundation, Inc.
    Inventors: Kristina M. Johnson, Gary D. Sharp
  • Patent number: 5073010
    Abstract: The disclosure describes an optically addressable spatial light modulator (OASLM) having a light sensitive member and a distorted helix ferroelectric liquid crystal (DHFLC). In a first embodiment a hydrogenated amorphous silicon (a-Si:H) photodiode layer is in physical contact with the DHFLC layer. In another embodiment an integrated circuit member includes a photosensitive area and an associated metal pad for each OASLM pixel, the metal pads in physical contact with corresponding DHFLC pixel areas. In the first embodiment, a low magnitude AC voltage (less than three to seven volts peak to peak) is connected to the OASLM as operating voltage, preferably in the absence of a DC offset voltage. The OASLM pixel areas of the OASLM are selectively addressed by a writing light wavefront, to thereby activate corresponding pixel areas of the light sensitive member.
    Type: Grant
    Filed: May 11, 1990
    Date of Patent: December 17, 1991
    Assignee: University of Colorado Foundation, Inc.
    Inventors: Kristina M. Johnson, Chongchang Mao, Ibrahim S. Abdulhalim