Patents by Inventor Richard A. Keller

Richard A. Keller 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: 4771840
    Abstract: An articulated shopping cart-tractor unit with a seat is provided for the handicapped. The tractor unit is connected to a conventional shopping cart by a bracket and coupling.
    Type: Grant
    Filed: April 15, 1987
    Date of Patent: September 20, 1988
    Assignee: Orthokinetics, Inc.
    Inventor: Richard A. Keller
  • Patent number: 4544274
    Abstract: The thermal lensing phenomenon is used as the basis for measurement of weak optical absorptions when a cell containing the sample to be investigated is inserted into a normally continuous-wave operation laser-pumped dye laser cavity for which the output coupler is deliberately tilted relative to intracavity circulating laser light, and pulsed laser output ensues, the pulsewidth of which can be related to the sample absorptivity by a simple algorithm or calibration curve. A minimum detection limit of less than 10.sup.-5 cm.sup.-1 has been demonstrated using this technique.
    Type: Grant
    Filed: June 8, 1982
    Date of Patent: October 1, 1985
    Assignee: The United States of America as represented by the United States Department of Energy
    Inventors: David A. Cremers, Richard A. Keller
  • Patent number: 4447153
    Abstract: An apparatus and method for the measurement of small differences in optical absorptivity of weakly absorbing solutions using differential interferometry and the thermooptic effect has been developed. Two sample cells are placed in each arm of an interferometer and are traversed by colinear probe and heating laser beams. The interrogation probe beams are recombined forming a fringe pattern, the intensity of which can be related to changes in optical pathlength of these laser beams through the cells. This in turn can be related to small differences in optical absorptivity which results in different amounts of sample heating when the heating laser beams are turned on, by the fact that the index of refraction of a liquid is temperature dependent. A critical feature of this invention is the stabilization of the optical path of the probe beams against drift. Background (solvent) absorption can then be suppressed by a factor of approximately 400. Solute absorptivities of about 10.sup.-5 cm.sup.
    Type: Grant
    Filed: June 8, 1982
    Date of Patent: May 8, 1984
    Assignee: The United States of America as represented by the United States Department of Energy
    Inventors: David A. Cremers, Richard A. Keller
  • Patent number: 4402606
    Abstract: The disclosure relates to an optogalvanic intracavity detector and method for its use. Measurement is made of the amount of light absorbed by atoms, small molecules and ions in a laser cavity utilizing laser-produced changes in plasmas containing the same atoms, molecules, or ions.
    Type: Grant
    Filed: February 25, 1981
    Date of Patent: September 6, 1983
    Inventors: Edward F. Zalewski, Richard A. Keller, Charles T. Apel
  • Patent number: 4184127
    Abstract: An apparatus and method for utilizing the opto-galvanic effect to perform ectroscopic or analytic investigations of atomic or molecular species. A sample of the substance to be analyzed is vaporized in an analytical flame, gas discharge tube, high temperature furnace or the like, and the vapor is irradiated with chopped or pulsed variable wavelength monochromatic light. The electrical resistance of the vapor is monitored as the frequency of the radiation is tuned through one or more electronic transition frequencies of the substance. The resistance spectrum resembles the optical absorption spectrum of the species in the vapor. The optogalvanic effect may also be used to frequency lock a laser to a transition frequency of a substance in a gas discharge cell.
    Type: Grant
    Filed: November 13, 1978
    Date of Patent: January 15, 1980
    Assignee: The United States of America as represented by the Secretary of Commerce
    Inventors: Robert B. Green, Richard A. Keller, Gabriel G. Luther, Peter C. Schenk, John C. Travis
  • Patent number: 4148586
    Abstract: An apparatus and method for utilizing the opto-galvanic effect to perform spectroscopic or analytic investigations of atomic or molecular species. A sample of the substance to be analyzed is vaporized in an analytical flame, gas discharge tube, high temperature furnace or the like, and the vapor is irradiated with chopped or pulsed variable wavelength monochromatic light. The electrical resistance of the vapor is monitored as the frequency of the radiation is tuned through one or more electronic transition frequencies of the substance. The resistance spectrum resembles the optical absorption spectrum of the species in the vapor. The opto-galvanic effect may also be used to frequency lock a laser to a transition frequency of a substance in a gas discharge cell.
    Type: Grant
    Filed: June 23, 1977
    Date of Patent: April 10, 1979
    Assignee: The United States of America as represented by the Secretary of Commerce
    Inventors: Robert B. Green, Richard A. Keller, Gabriel G. Luther, Peter C. Schenck, John C. Travis
  • Patent number: 4025406
    Abstract: An isotopic starting material consisting of a mixture of chlorine-35 and chlorine-37 isotopic species of an isotopic compound having the formula CYClX, wherein Y is O or S and X is Cl or F, such as thiophosgene, is selectively isotopically enriched by means of a laser-induced photochemical reaction between selected chlorine isotopic species in the starting material and a dialkoxyethylene, such as diethoxyethylene. The method is carried out by irradiating with laser radiation, a gaseous mixture at a reduced pressure of the isotopic starting material and the dialkoxyethylene, until a stable reaction product is formed. The wavelength of the radiation is selected so as to selectively excite at least one but less than all of the chlorine isotopic species in the starting material, thereby causing the excited species to preferentially react with the dialkoxyethylene.
    Type: Grant
    Filed: January 28, 1976
    Date of Patent: May 24, 1977
    Assignee: The United States of America as represented by the Secretary of Commerce
    Inventors: Michel Lamotte, Harry J. Dewey, Richard A. Keller, Joseph J. Ritter
  • Patent number: 3944928
    Abstract: A communication system comprising a transmitter for radiating a carrier frequency signal, which may be modulated, to a data station. The station includes a rectifier for rectifying the received carrier signal to provide energy to the station elements. A data source at the station produces a data signal representative of the information to be transmitted. A harmonic generator produces harmonics of the carrier signal and the harmonic signal is modulated with the data or information signal. An antenna radiates the modulated harmonic signal to a receiver which demodulates the received signal to extract the information therefrom. Thus, a completely self-contained and economic system is provided, since the carrier signal per se supplies the energy to operate the data station.Additionally, the communication system may include a carrier signal having an address encoded therein and the station may comprise an address decoder so that only a selected addressed station will transmit the desired data at any one time.
    Type: Grant
    Filed: July 1, 1974
    Date of Patent: March 16, 1976
    Assignee: Microlab/FXR
    Inventors: Harry A. Augenblick, Richard Keller