Abstract: Methods and systems consistent with this invention identify a buried object using array-based ground penetrating radar having a control device, a plurality of transmit antennas, and a plurality of receive antennas. Such methods and systems receive a transmit timing input signal and a receive timing input signal. Such methods and systems comprise a first delay circuit for receiving the transmit timing input signal and generating a number of intermediate transmit timing signals delayed with respect to each other by a delay time, and transmit output switch circuit to select either the transmit timing input signal or a corresponding one of the intermediate transmit timing signals as a corresponding output transmit timing signal.

Abstract: An optical quadrature interferometer is presented. The optical quadrature interferometer uses a different state of polarization in each of two arms of the interferometer. A light beam is split into two beams by a beamsplitter, each beam directed to a respective arm of the interferometer. In one arm, the measurement arm, the light beam is directed through a linear polarizer and a quarter wave plate to produce circularly polarized light, and then to a target being measured. In the other arm, the to reference arm, the light beam is not subject to any change in polarization. After the light beams have traversed their respective arms, the light beams are combined by a recombining beamsplitter. As such, upon the beams of each arm being recombined, a polarizing element is used to separate the combined light beam into two separate fields which are in quadrature with each other.

Abstract: Disclosed is separation of the compressional and shear components of the wavefield measured in 3-component vertical seismic profiling. The separation involves working in the zx plane defined by the borehole axis (z) and the surface seismic source, and in successive and overlapping windows each defined by (i) a depth interval centered at the depth level currently being processed and including several depth levels above and below and (ii) a time interval sufficiently long to include the receipt of the relevant seismic energy by the geophones.

Abstract: Diffraction tomography systems and methods are disclosed for the reconstruction of physical properties of two and three-dimensional objects from information collected by detectors located along an arbitrary surface in space. The sources of energy investigating the object may likewise be located along an arbitrary surface. Optimal filtered backpropagation techniques and preprocessing required for such reconstructions are disclosed for systems utilizing plane wave sources, and for systems using fan beam cylindrical or spherical wave insonification. The preprocessing and filtered backpropagation techniques are shown to simplify for the cases of circular boundaries, and other separable boundaries within the Helmholtz equation.

Abstract: Diffraction tomography systems and methods are disclosed for the reconstruction of physical properties of two- and three-dimensional objects from information collected by detector arrays which are fixed in space. Improved preprocessing procedures and an optimal filtered backpropagation technique are disclosed for both geophysical and ultrasonic diffraction tomography systems and methods. A novel method for reconstructing properties of three-dimensional objects and slices thereof in real time is also disclosed. An optimal filtered backpropagation technique for the backscatter mode is further disclosed.

Abstract: Diffraction tomography systems and methods are disclosed for the reconstruction of physical properties of two and three-dimensional objects from information collected in one or more diffraction tomographic procedures. A diffraction tomographic system is comprised of a continuous or pulsed source of wave energy, a detecting system for the measurement of the amplitude and/or phase of the scattered field resulting from the wave energy interacting with a two or three-dimensional object, a processing and filtering system for processing and filtering the measured signals according to a filtered backpropagation technique thereby generating arrays which are used to reconstruct the object properties, and a graphics display system for displaying obtained reconstructions. Specific embodiments include ultrasound transmission computed tomography; well-to-well electromagnetic and sonic tomography; subsurface electromagnetic or seismic exploration; and X-ray transmission tomography.

Abstract: Adaptive optics with controllable delay in a matrix of regions focuses the image of an object upon a detector array in an image plane that provides a signal set representative of the radiant energy incident upon a matrix of locations in the image plane. An image signal processor processes this signal set to provide a wavefront error signal representative of the estimated wavefront phase distortion of the radiant energy incident upon the detector array. A control system responds to this wavefront error signal to effect alteration of the phase delay introduced by the adaptive optics to reduce the phase distortion of radiant energy incident upon the detector array.