Patents by Inventor Grant R. Gerhart
Grant R. Gerhart 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).
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Patent number: 7349087Abstract: A method of determining polarization profiles of points in a scene from video frames using Stokes parameters. The method includes emitting scene light rays from points in a region in a scene, and emitting a correlator light ray from a correlator. The correlator includes a uniform light source, a second linear polarizer, and a fixed retarder. The method further includes substantially simultaneously transmitting the scene light rays and the correlator light ray through a color filter and a Stokes filter that includes a rotating retarder having angular positions ?, and a first linear polarizer having a transmission axis to a video camera having a video frame, projecting onto respective pixels in the video frame and recording as two-dimensional (2-D) arrays images corresponding to the scene light rays and the correlator light ray, and downloading the images into the computer system and storing the images into a memory in the computer system.Type: GrantFiled: June 18, 2007Date of Patent: March 25, 2008Assignee: The United States of America as represented by the Secretary of the ArmyInventors: Grant R. Gerhart, Roy M. Matchko
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Patent number: 7295312Abstract: A system for determining polarization profiles of points in a scene from video frames using Stokes parameters includes a scene having a region that emits scene light rays that correspond to the points in the scene, an optical chopper controller, a rotating Stokes filter wheel that includes five trigger holes, three rotating linear polarizers, a circular polarizer, and a reference screen, a color filter, a video camera having a video frame, and a computer system having a frame grabber apparatus. The scene light rays are transmitted through the Stokes filter and the color filter to the video camera.Type: GrantFiled: May 10, 2006Date of Patent: November 13, 2007Assignee: United States of America as represented by the Secretary of the ArmyInventors: Grant R. Gerhart, Roy M. Matchko
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Patent number: 7274449Abstract: A system for determining polarization profiles of points in a scene from video frames using Stokes parameters includes a scene having a region that emits scene light rays that correspond to the points in the scene, a color filter, a Stokes filter that includes a rotating retarder having angular positions ?, and a first linear polarizer having a transmission axis, a correlator that emits a correlator light ray, and that comprises a uniform light source, a second linear polarizer, and a fixed retarder, a video camera having a video frame, and a computer system.Type: GrantFiled: June 20, 2005Date of Patent: September 25, 2007Assignee: United States of America as represented by the Secretary of the ArmyInventors: Grant R. Gerhart, Roy M. Matchko
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Patent number: 7230700Abstract: A method for determining and displaying polarization profiles of points in a scene from a single imaging detector array, which utilizes a filter system comprised of a retarder, four linear polarizers, four lenses, a color filter, camera lens and CCD video camera. Light from points in a scene are transmitted through the system and exits with attenuated intensities unique for each wavelength of the light. A narrowband color filter selects the wavelength of interest. The four lenses in the system produce four images of the scene, which are recorded as a single CCD-image. The attenuated intensities in each of the four scene-images are used to calculate the Stokes parameters for selected points in the scene for the selected wavelength. A computer program separates the four scene-images in the CCD-image, crops, registers them and calculates the Stokes parameters for each point in the cropped scene.Type: GrantFiled: September 25, 2006Date of Patent: June 12, 2007Assignee: United States of America as represented by the Secretary of the ArmyInventors: Grant R. Gerhart, Roy M. Matchko
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Patent number: 5949480Abstract: A method for obtaining spectral radiation data for points in a field of view utilizes a broad band variable filter to produce different intensity distributions on a photocell array. The array is in the focal plane of a camera and photocell locations correspond to points in the field of view. The variable filter has a sequence of optical train elements comprised of a first linear polarizer, a body of optically active material, a retarder and a second linear polarizer. A series of radiance measurements are taken at each photocell of the array and at least one of the optical train components is repositioned between measurements. For each photocell, a collection of photocell values is stored in a computer memory and is converted to a system of linear equations. Intensities for spectral components of light incident thereon are derived for each photocell. The method can be used to create a two-dimensional intensity map for the pixel array for each wavelength measured.Type: GrantFiled: March 3, 1997Date of Patent: September 7, 1999Assignee: The United States of America as represented by the Secretary of the ArmyInventors: Grant R. Gerhart, Roy M. Matchko
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Patent number: 5734473Abstract: A method for determining polarization profiles of individual wavelengths hin a polychromatic source utilizes a variable filter system comprised of a retarder and a linear polarizer. Polychromatic light from the source is transmitted through the system and exits therefrom with attenuated intensities unique for each wavelength of the light. The attenuated intensities are recorded by a spectroradiometer and used to calculate Stokes parameters for each wavelength. The inherent problem of the retarder introducing a different phase differential for each individual wavelength transmitted therethrough is solved by expressing the Stokes parameters explicitly as a function of wavelength. The primary purpose of the method is to obtain the four Stokes parameters for individual bands of wavelength within a polychromatic light beam.Type: GrantFiled: February 27, 1997Date of Patent: March 31, 1998Assignee: United States of America as represented by the Secretary of the ArmyInventors: Grant R. Gerhart, Roy M. Matchko
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Patent number: 4719160Abstract: A method of making a white light hologram is disclosed. A diffraction grating is placed in contact with a film emulsion to provide a reference and object beam from the same light source.Type: GrantFiled: June 11, 1986Date of Patent: January 12, 1988Inventors: Grant R. Gerhart, Gregory Arutunian
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Patent number: 4490851Abstract: This invention relates to surveillance and counter-surveillance classificon of military vehicles using one-dimensional analysis of the target images. A two-dimensional image is digitized into a n by n pixel matrix which is summed along each row and column to produce a pair of n-component vectors which are invariant under image translation or rotation. A one-dimensional Fourier transform can be obtained from either or both of these two vectors. The image vectors are useful in the identification of U.S. and threat vehicle targets, or in the detection of target image motion.Type: GrantFiled: April 16, 1982Date of Patent: December 25, 1984Assignee: The United States of America as represented by the Secretary of the ArmyInventors: Grant R. Gerhart, James M. Graziano
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Patent number: 4462257Abstract: A novel transducer able to detect ultrasonic surface waves over a wide frency band. The transducer is essentially a grid or series of bars connected in parallel or series. The sensitivity of the transducer increases proportionally with frequency for constant surface wave amplitude. The transducer detects surface waves by providing a resistance change across the transducer output terminal proportional to the surface wave strain. The output voltage can be calibrated to give a direct reading of the surface wave amplitude. The coupling problems which are inherent in most transducer configurations are drastically reduced for this strain sensitive detector. The modulation of the grid excitation voltage provides a means for mixing two signals by giving the direct product of the signals in time. Complicated filtering functions can be built into the grid detector by varying the bar spacing in a manner analogous to the piezoelectric interdigital grid transducer.Type: GrantFiled: September 29, 1982Date of Patent: July 31, 1984Assignee: The United States of America as represented by the Secretary of the ArmyInventors: Grant R. Gerhart, Douglas N. Rose
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Patent number: 4121467Abstract: It is often desirable to measure absolute and relative USW velocities in a specimen. One example is a specimen which is to be tested for residual surface stresses. The specimen is provided with two scratches which are parallel and a known distance apart. An ultrasonic surface wave (USW) transducer is attached to the surface of the specimen in such a way as to efficiently transfer USW energy to the specimen. During testing, the incident pulse from the transducer is partially reflected at each scratch. The same transducer generates and detects both reflections. The transducer output goes through a clipping circuit which clips the large incident voltage spikes in the output and passes the smaller, echo voltages through to an oscilloscope. The oscilloscope horizontal sweep is driven at a frequency which is the reciprocal of the difference in arrival times between the two reflected pulses.Type: GrantFiled: May 31, 1977Date of Patent: October 24, 1978Assignee: The United States of America as represented by the Secretary of the ArmyInventor: Grant R. Gerhart