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US 9,316,734 B2Granted
Free-hand scanning and imaging
AssigneeThe Curators of the University of Missouri
InventorsJoseph T. Case, Mohammad Tayeb Ghasr, Reza Zoughi
Life of this patent
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Abstract
Wideband synthetic aperture radar (SAR) imaging. A probe transmits a signal through its aperture incident to an object located in a medium of interest remotely from the probe. The probe receives through the aperture a plurality of nonuniformly sampled reflected signals from the object as the probe moves in a measurement plane located a predetermined distance from the object. A processor executes a SAR-based reconstruction algorithm to generate an image.
Claims23
A wideband synthetic aperture radar (SAR) imaging system, comprising:
- a probe having an aperture through which a signal is transmitted incident to an object located in a medium of interest remotely from the probe and through which a plurality of nonuniformly sampled reflected signals from the object are received by the probe as the probe moves in a measurement plane located a predetermined distance from the object;
- a memory for storing measurement data representative of the reflected signals collected by the probe;
- a processor for executing a plurality of computer-executable instructions for a SAR-based reconstruction algorithm, said instructions comprising:
- instructions for performing a spectral estimation based on the measurement data;
- instructions for transforming a frequency component of the spectral estimation as a function of the medium of interest;
- instructions for obtaining an intermediate three-dimensional SAR image from the transformed spectral estimation data using Fourier transforms;
- instructions for segmenting the intermediate three-dimensional SAR image into a plurality of segments in an image domain, wherein each segment includes a spatial bandwidth of a plurality of spatial bandwidths of the intermediate three-dimensional SAR image;
- instructions for transforming each of the plurality of segments from the image domain to a measurement domain, wherein each of the plurality of segments is represented as partial data;
- instructions for performing an optimization operation on each of the plurality of segments based on a comparison between the partial data thereof and the measurement data;
- instructions for recombining the plurality of segments to produce a final three-dimensional SAR image;
- and
- a display responsive to the processor for presenting the final three-dimensional SAR image to a user.
9 more elements
A method of generating a three dimensional image of a specimen under test (SUT) comprising:
- transmitting, via a probe, a signal within a predetermined operating bandwidth;
- tracking nonuniform two-dimensional movement of the probe within a measurement plane remote from the SUT;
- receiving, via the probe, signals reflected from the SUT during the movement of the probe;
- storing reflection coefficient data based on the reflected signals as distributed measurement positions within the measurement plane by recording the signals at discrete frequencies throughout the operating bandwidth;
- processing the stored data into a wide band, synthetic aperture image by implementing a synthetic aperture radar (SAR) algorithm;
- displaying the image to a user in real-time;
- further processing the image to perform an optimization objective, wherein the optimization includes reducing the error between components derived from a SAR-based transform and an R-SAR-based transform;
- and
- further displaying the optimized image to the user.
6 more elements
A wideband synthetic aperture radar (SAR) imaging system, comprising:
- a signal source for generating a signal with a predetermined operating bandwidth;
- a transceiver antenna coupled to the signal source, the antenna having an aperture through which the signal is transmitted incident to an object located in a medium and through which a plurality of nonuniformly sampled reflected signals from the object are received by the antenna as the antenna moves nonuniformly in a plane located a predetermined distance from the object;
- a memory for storing signal data, the signal data comprising nonuniformly sampled reflected signals collected at the aperture;
- a processor executing a plurality of computer-executable instructions for a real-time, post-processing, reconstruction algorithm comprising:
- instructions for estimating a two-dimensional spatial spectrum based on the signal data to provide a uniformly sampled spectrum;
- instructions for estimating the uniformly sampled spectrum to remove or minimize image artifacts;
- instructions for reconstructing uniformly sampled data from nonuniformly sampled data to remove or minimize image artifacts;
- instructions for forming a SAR image of the object from the estimated uniform spectrum;
- instructions for dividing the reconstructed SAR image into a plurality of segments;
- instructions for applying a R-SAR transform to each of the segments;
- instructions for filtering and reconstructing the data for each of the segments and summing each of the filtered segments to create reconstructed data;
- instructions for applying a SAR transform to the reconstructed data to create a three-dimensional SAR image;
- and
- a display for presenting the three-dimensional SAR image to a user.
11 more elements
Dependencies are inferred from the claim text.