NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Implications of Microwave Holography Using Minimum Required Frequency Samples for Weakly- and Strongly-Scattering IndicationsMicrowave imaging techniques, an integral component of nondestructive testing and evaluation (NDTE), have received significant attention in the past decade. These techniques have included the implementation of synthetic aperture focusing (SAF) algorithms for obtaining high spatial resolution images. The next important step in these developments is the implementation of 3-D holographic imaging algorithms. These are well-known wideband imaging technique requiring a swept-frequency (i.e., wideband), which unlike SAF that is a single frequency technique, are not easily performed on a real-time basis. This is due to the fact that a significant number of data points (in the frequency domain) must be obtained within the frequency band of interest. This not only makes for a complex imaging system design, it also significantly increases the image-production time. Consequently in an attempt to reduce the measurement time and system complexity, an investigation was conducted to determine the minimum required number of frequency samples needed to image a specific object while preserving a desired maximum measurement range and range resolution. To this end the 3-D holographic algorithm was modified to use properlyinterpolated frequency data. Measurements of the complex reflection coefficient for several samples were conducted using a swept-frequency approach. Subsequently, holographical images were generated using data containing a relatively large number of frequency samples and were compared with images generated by the reduced data set data. Quantitative metrics such as average, contrast, and signal-to-noise ratio were used to evaluate the quality of images generated using reduced data sets. Furthermore, this approach was applied to both weakly- and strongly-scattering indications. This paper presents the methods used and the results of this investigation.
Document ID
20100032972
Document Type
Conference Paper
Authors
Fallahpour, M.
(Missouri Univ. of Science and Technology Rolla, MO, United States)
Case, J. T.
(Missouri Univ. of Science and Technology Rolla, MO, United States)
Kharkovsky, S.
(Missouri Univ. of Science and Technology Rolla, MO, United States)
Zoughi, R.
(Missouri Univ. of Science and Technology Rolla, MO, United States)
Date Acquired
August 25, 2013
Publication Date
July 18, 2010
Subject Category
Electronics And Electrical Engineering
Report/Patent Number
M10-0301
Meeting Information
36th Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE) Conference(San Diego, CA)
Funding Number(s)
CONTRACT_GRANT: NNX09AF81G
Distribution Limits
Public
Copyright
Public Use Permitted.

Available Downloads

NameType 20100032972.pdf STI
No Preview Available