Patents by Inventor Clifford R. Pollock

Clifford R. Pollock 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: 4991924
    Abstract: Fiber optic switches using layers of cholesteric or chiral nematic liquid crystals (CLCs) are disclosed. The CLC layer acts both as a polarization beamsplitter and as a reflector by decomposing incoming unpolarized light into two orthogonal circularly polarized components. In a number of embodiments, switchable waveplates are employed to controllably switch the polarization direction of each of the polarization components. The components are then reflected back toward the CLC layer where they are recombined into a transmitted unpolarized beam. The direction of transmission depends on the circular sense of the polarized components, and therefore on the state of the switchable waveplates. In other embodiments, the CLCs are used actively by selectively exposing them to electric or magnetic fields or to heat which cause a phase change that temporarily neutralizes the circular polarization effect. In this manner, the CLCs can be used as switch elements themselves.
    Type: Grant
    Filed: May 19, 1989
    Date of Patent: February 12, 1991
    Assignees: Cornell Research Foundation, Inc., E. I. du Pont de Nemours & Company
    Inventors: Narendra K. Shankar, Jeffrey A. Morris, Clifford R. Pollock, Christopher P. Yakymyshyn, T. Wilson Whitehead
  • Patent number: 4990322
    Abstract: A powerful and stable color center laser is provided by additively colored NaCl:OH.sup.- crystals. The OH.sup.- impurity is the key dopant for creating color center lasing in NaCl, providing an output tunable over the 1.41 to 1.81 .mu.m region. In addition, modelocked pulses of 5 psec duration are available in a synchronously pumped arrangement, tunable from 1.47 to 1.73 .mu.m.
    Type: Grant
    Filed: July 19, 1990
    Date of Patent: February 5, 1991
    Assignee: Cornell Research Foundation, Inc.
    Inventors: Clifford R. Pollock, Joseph F. Pinto, Efstratios Georgiou
  • Patent number: 4964133
    Abstract: The laser material of the invention comprises an alkali-halide crystal, with a rocksalt crystallographic structure, containing point defects selected from the group consisting of F.sub.3 or R, F.sub.4 and N.sub.2 color centers. The preferred laser material is based on the neutral "N.sub.2 " color center defect. The alkali halide can be any alkali halide, for example, lithium, sodium, potassium and rubidium chloride, bromide and fluoride. The preferred alkali halide is potassium chloride. The lasers of the invention comprise a stable near-infrared laser which can be tuned in the case of KCl for example from 1.23 to 1.35 .mu.m, and can be optically pumped at 1.06 .mu.m, for example from a Q-switched Nd:YAG laser. The laser of the invention represent the first reported laser based on N.sub.2 -center transitions, and appear to be the first stable laser using a charge-neutral color center in pure alkali halide hosts.
    Type: Grant
    Filed: April 14, 1989
    Date of Patent: October 16, 1990
    Assignee: Cornell Research Foundation, Inc.
    Inventors: Clifford R. Pollock, Efstratios T. Georgiou, Timothy J. Carrig
  • Patent number: 4947035
    Abstract: The present invention relates, in general, to optical transducers, and more particularly to optical transducers utilizing the Faraday effect and responsive to changes in a magnetic field produced by a target. These changes in magnetic field produce a modulation in the light passing through a ferrite crystal, and this modulation can be used to measure mechanical motion, proximity, and related parameters.
    Type: Grant
    Filed: August 8, 1988
    Date of Patent: August 7, 1990
    Assignee: Cornell Research Foundation, Inc.
    Inventors: Brian J. Zook, Clifford R. Pollock, Jeffrey A. Morris
  • Patent number: 4839009
    Abstract: A powerful and stable color center laser is provided by additively colored NaCl:OH.sup.- crystals. The OH.sup.- impurity is the key dopant for creating color center lasing in NaCl, providing an output tunable over the 1.41 to 1.81 .mu.m region. In addition, modelocked pulses of 5 psec duration are available in a synchronously pumped arrangement, tunable from 1.47 to 1.73 .mu.m.
    Type: Grant
    Filed: June 5, 1986
    Date of Patent: June 13, 1989
    Assignee: Cornell Research Foundation, Inc.
    Inventors: Clifford R. Pollock, Joseph F. Pinto, Efstratios Georgiou