Flaw Detection and Imaging by High-Resolution Synthetic Pulse Pulse Holography
Many applications in the field of non-destructive testing are concerned with flaw detection and/or imaging. In such applications conventional holography using acoustic waves has been applied with some success. This technique has some disadvantages which limit the applicability of conventional (monofrequency) holography /1/. Conventional holography has very poor axial resolution, and with optical reconstruction significant image distortion as well as a combination of acoustical and optical speckle noise are seen. Good axial resolution can be obtained using wide-band holography and with computer reconstruction the problem of laser generated optical speckle in optical reconstruction is eliminated.
KeywordsLookup Table Axial Resolution Object Area Bandlimited Signal Acoustical Holography
Unable to display preview. Download preview PDF.
- /2/.Frederick, J., Sydel, J., Fairchild, R., Improved Ultrasonic Nondestructiv Testing of Pressure Vessels, Yearly Progress Report, Aug 1, 1974, Nuclear Regulatory Commission NUREG 0007–1, Washington, D.C. (1974).Google Scholar
- /3/.Sato, T., Ikeda, O., Ohshima, H., Fujikura, H., A Few Effective Pre-processings in Synthetic Aperture Sonar System, Acoustical Holography ed., Kessler, vol. 7, pp 569–582 (1977).Google Scholar
- /6/.Ermert, H., Karg, R., Multifrequency Acoustical Holography, IEEE Transactions on Sonics and Ultrasonics, SU–26: 4, pp 279–286 (July 1979).Google Scholar
- /7/.Erhard, A., Wüstenberg, H., Kutzner, J., The accuracy of Flaw Size Determination by Ultrasonics, British Journal of Non-Destructive Testing, pp 39–43 (Jan 1979).Google Scholar
- /8/.Dick, M., Dick, D., McLeod, F., Kindig, N., Ultrasonic Synthetic Aperture Imaging, Acoustical Holography, ed. Kessler, Vol. 7, pp 327–346 (1977).Google Scholar
- /9/.Duck, F., Johnson, S., Greenleaf, J., Samayoa, W., Digital Image Focussing in the Near Field of a sampled Acoustic Aperture, Ultrasonics, p 83–88 (March 1977).Google Scholar