- Email: [email protected]
Resolution of scanning acoustic microscope in sub-surface imaging
39057
Somekh, M.G.; Zhang, D.; Rowe, J.M.
Vibrating sample method for amplitude and phase measurements with the acoustic microscope Electronics Letters, Vol. 24, No. 20, pp. 1262-1263 (29 Sep. 1988) The letter describes how the scanning acoustic microscope may be operated in a continuous wave mode. By oscillating the sample by approximately a few hundred angstroms, single frequency amplitude and phase measurements may be obtained with the acoustic microscope. We also show that the method should allow very high frequency quantitative operation of the microscope, where conventional pulse echo methods would fail. A system implementation and preliminary results are presented. 39051
Khandelwal, P.K.
Nondestructive evaluation of structural ceramics by photoacoustic microscopy fmal report National Aeronautics and Space Adminstration, Lewis Research Center, Cleveland, Ohio (United States), N88-16868, NASA-CR180858, 110 pp. (Jun. 1987) Photoacoustic microscopy (PAM) has been shown to detect such failure initiating defects in silicon base materials. The objective of the NASA funded Nondestructive Evaluation of Structural Ceramics by Photoacoustic Microscopy (PAM) program was (1) to develop a photoacoustic microscopy imaging system, (2) to sequentially characterize silicon nitride material in green, as-fired, and machined stages of ceramic fabrication process, and (3) to detect and predict failure initiating defects in silicon nitride. A PAM digital data acquisition, imaging, and analysis system was successfully developed and used during this program. Menu driven algorithms were developed in machine language and implemented for rapid data acquisition and image processing. The system is capable of creating 16 color images with magnification, scroll images in all four directions on the CRT screen, and threshold acquired PAM signals. In addition-, flaw location, size, and the detected PAM signal can be quantified. 38966
Gopalsami, N.; Ellingson, W.A.; Roberts, R.A.; Rose, D.N.
The resolution of the scanning acoustic microscope in sub-surface imaging is theoretically investigated. A formula for the point spread function is derived by assuming that a delta-functional point reflector exists inside a flat-topped solid specimen. The resolution is then evaluated using this point spread function and Rayleigh's criterion. Calculated results show that higher resolution can be obtained by detecting the shear waves than by detecting the longitudinal waves. 38679
Adams, T.
Acoustic microscopes probe internal structures Ceramic Industry, Vol. 130, No. 3, pp. 21-24 (Mar. 1988) A comparison of the use of three types of acoustic microscopes for detecting defects such as variations in porosity, cracks, voids and inclusions in ceramics, is presented. The scanning laser acoustic microscope (S.L.A.M.) works in a transmission mode. The C-mode scanning acoustic microscope or C-SAM works on reflection as does the scanning acoustic microscope or S.A.M.. This latter specialises in surface and near surface imaging and does not penetrate ceramic samples. 38636
Fatkin, D.G.P.; Briggs, G.A.D.; Scruby, C.B.
Acoustic microscopy of low ductility materials United Kingdom Atomic Energy Authority, Harwell, A E R E - R 12848, 59 pp. (Dec. 1987) This paper describes the application of acoustic microscopy to two important classes of low ductility material: engineering ceramics and ceramic fibre composites. Images of a wide range of near-surface defects are presented for the six ceramics studied, including porosity and microcracks. An application to crack length determination during indentation tests is also discussed. In the composites, there were systematic variations in contrast from the fibre-matrix interface, which appeared to correlate with changes in interracial strength. Finally the line-focus microscope was used to demonstrate how the Rayleigh velocity and attenuation can be used to characterise the microstructure of ceramics and ceramic composites. 38587
Keisuke Honda
Nondestructive evaluation of pack-diffusion coatings: A review and preliminary results
Multi-color displaying ultrasonic microscope
Argonne National Laboratory, Argonne, Illinois (United States), ANL-FE- 87-7, DE88-005491, 36 pp. (Dec. 1987) This report reviews potential nondestructive evaluation (NDE) methods for coatings applicable to heat recovery systems of coal gasifiers. The review focuses mainly on aluminized, chromized, or simultaneously aluminized/chromized coatings that are produced by pack-diffusion processes on low-alloy steels. Nondestructive evaluation is required for characterization of as-received coatings relative to acceptance criteria, and for inspection of field fabrication and repairs. A candidate NDE technique must ideally be capable of detecting fine cracks, inclusions, voids, and AI/Cr concentration profiles. In general, a spatial resolution on the order of tens of micrometers is required. The candidate NDE methods reviewed are thermal wave imaging, scanning acoustic microscopy, ultrasonic backscattered surface waves, eddy-current testing, and X-ray fluorescence.
38417
38773
Klima, S.J.; Baaklini, G.Y.
Ultrasonic characterization of structural ceramics Materials Analysis by Ultrasonics - Metals, Ceramics, Composites. Edited by A. Vary. pp. 112-118. Noyes Data Corporation, New Jersey, United States (1987). Ultrasonic velocity and attenuation measurements were used to characterize density and microstructure in monolithic silicon nitride and silicon carbide. Research samples of these structural ceramics exhibited a wide range of density and microstructural variations. It was shown that bulk density variations correlate with and can be estimated by velocity measurements. Variations in microstructural features such as grain size or shape and pore morphology had a minor effect on velocity. However, these features had a pronounced effect on ultrasonic attenuation. The ultrasonic results are supplemented low- energy radiography and scanning laser microscopy. 38752
Generazio, E.R.; Roth, D.J.
Quantitative flaw characterization with scanning laser acoustic microscopy Materials Analysis by Ultrasonics - Metals, Ceramics, Composites. Edited by A Vary. pp. 331-348. Noyes Data Corporation, New Jersey, United States (1987) Surface roughness and diffraction are two factors that have been observed to affect the accuracy of flaw characterization with scanning laser acoustic microscopy. Inaccuracies can arise when the surface of the test sample is acoustically rough. It is shown that, in this case, Snell's law is no longer valid for determining the direction of sound propagation within the sample. This paper investigates the relationship between the direction of sound propagation within the sample, the apparent flaw depth, and the sample's surface roughness. Diffraction effects can mask the acoustic images of minute flaws and make it difficult to establish their size, depth, and other characteristics. It is shown that for Fraunhofer diffraction conditions the acoustic image of a subsurface defect corresponds to a two-dimensional Fourier transform. Transforms based on simulated flaws are used to infer the size and shape of the actual flaw. 38723
Ohno, M.
Resolution of scanning acoustic microscope in sub-surface imaging Japanese Journal of Applied Physics, Vol. 27, No. 5, pp. 734-737 (May 1988)
44
U.S. Patent No. 4,674,333 (23 Jun. 1987) An ultrasonic microscope which displays results in two colours has been developed. Ultrasonic waves are bounced of the object to be inspected and detected using a receiving element. The transmission and reception elements shift with respect to the object in two dimension and resultant signals are displayed in two colours on a cathode ray tube.
Kushibiki, J.; lshikawa, T.; Chubachi, N.
Precise measurement of film thickness by line-focus-beam acoustic
microscope Ultrasonics International 87, Conference Proceedings, London (United Kingdom), 6-9 Jul. 1987. pp. 291-296. Butterworth and Co. (Publishers) Ltd., Guildford, Surrey (1987) The line-focus-beam (LFB) acoustic microscope has been applied to film thickness measurements utilizing the velocity dispersion of leaky waves. The measurement method is investigated theoretically and experimentally, taking typical configurations of an isotropic sample of Au-film on fused quartz and an anisotropic sample of Au-film on silicon wafer. In general, there exist multiple leaky modes in the measurement for such layered media, so that a proper mode selection should be made to get higher accuracy. The thickness resolution of 2 angstroms is achieved for a 3000 angstrom Au-film deposited on fused quartz. For the anisotropic sample, it is also shown that the LFB system is much superior in quantitative measurements to the conventional point4ocus- beam (PFB) system.
Kolodziejczyk, E.; Fernandez-Graf, M.R.; Saurel, J.M.; Fryder, V.; Saied, A.; Attal, J.; Rey, V.
38416
Acoustic microstructure of green coffee Ultrasonics International 87, Conference Proceedings, London (United Kingdom), 6-9 Jul. 1987. pp. 284-290. Butterworth and Co. (Publishers) Ltd., Guildford, Surrey (1987) The rapid visualization of the actual microstructure of biologic specimens is of high interest and is now rendered feasible on the intact sample by acoustic microscopy. Nevertheless, practical applications of this method are still limited and relatively little has been done to explore its potential. As an example, we describe here the use of acoustic microscopy as a rapid and efficient method for the study of plant microstructure. 38415
Chen, C.H.; Meyyappan, A.; Wade, G.
Limited angle planar diffraction tomography: A first-order solution Ultrasonics International 87, Conference Proceedings, London (United Kingdom), 6-9 Jul. 1987. pp. 277-283. Butterworth and Co. (Publishers) Ltd., Guildford, Surrey (1987) In this paper, we present a first-order analysis of image reconstruction using limited-angle data. A difference-equation technique is used to obtain the solution. The range of incident angles over which useful projection data are not available is employed as a parameter. We show precisely how the expected mean-squares error increases as the range of incident angles decreases. 38387
Addison, R.C. Jr.," Somekh, M.; Rowe, J.M.; Briggs, G.A.D.
Characterization of thin-film adhesion with the scanning acoustic microscope An International Symposium on Pattern Recognition and Acoustical
NDT International February 1990
Somekh, M.G.; Zhang, D.; Rowe, J.M.
Vibrating sample method for amplitude and phase measurements with the acoustic microscope Electronics Letters, Vol. 24, No. 20, pp. 1262-1263 (29 Sep. 1988) The letter describes how the scanning acoustic microscope may be operated in a continuous wave mode. By oscillating the sample by approximately a few hundred angstroms, single frequency amplitude and phase measurements may be obtained with the acoustic microscope. We also show that the method should allow very high frequency quantitative operation of the microscope, where conventional pulse echo methods would fail. A system implementation and preliminary results are presented. 39051
Khandelwal, P.K.
Nondestructive evaluation of structural ceramics by photoacoustic microscopy fmal report National Aeronautics and Space Adminstration, Lewis Research Center, Cleveland, Ohio (United States), N88-16868, NASA-CR180858, 110 pp. (Jun. 1987) Photoacoustic microscopy (PAM) has been shown to detect such failure initiating defects in silicon base materials. The objective of the NASA funded Nondestructive Evaluation of Structural Ceramics by Photoacoustic Microscopy (PAM) program was (1) to develop a photoacoustic microscopy imaging system, (2) to sequentially characterize silicon nitride material in green, as-fired, and machined stages of ceramic fabrication process, and (3) to detect and predict failure initiating defects in silicon nitride. A PAM digital data acquisition, imaging, and analysis system was successfully developed and used during this program. Menu driven algorithms were developed in machine language and implemented for rapid data acquisition and image processing. The system is capable of creating 16 color images with magnification, scroll images in all four directions on the CRT screen, and threshold acquired PAM signals. In addition-, flaw location, size, and the detected PAM signal can be quantified. 38966
Gopalsami, N.; Ellingson, W.A.; Roberts, R.A.; Rose, D.N.
The resolution of the scanning acoustic microscope in sub-surface imaging is theoretically investigated. A formula for the point spread function is derived by assuming that a delta-functional point reflector exists inside a flat-topped solid specimen. The resolution is then evaluated using this point spread function and Rayleigh's criterion. Calculated results show that higher resolution can be obtained by detecting the shear waves than by detecting the longitudinal waves. 38679
Adams, T.
Acoustic microscopes probe internal structures Ceramic Industry, Vol. 130, No. 3, pp. 21-24 (Mar. 1988) A comparison of the use of three types of acoustic microscopes for detecting defects such as variations in porosity, cracks, voids and inclusions in ceramics, is presented. The scanning laser acoustic microscope (S.L.A.M.) works in a transmission mode. The C-mode scanning acoustic microscope or C-SAM works on reflection as does the scanning acoustic microscope or S.A.M.. This latter specialises in surface and near surface imaging and does not penetrate ceramic samples. 38636
Fatkin, D.G.P.; Briggs, G.A.D.; Scruby, C.B.
Acoustic microscopy of low ductility materials United Kingdom Atomic Energy Authority, Harwell, A E R E - R 12848, 59 pp. (Dec. 1987) This paper describes the application of acoustic microscopy to two important classes of low ductility material: engineering ceramics and ceramic fibre composites. Images of a wide range of near-surface defects are presented for the six ceramics studied, including porosity and microcracks. An application to crack length determination during indentation tests is also discussed. In the composites, there were systematic variations in contrast from the fibre-matrix interface, which appeared to correlate with changes in interracial strength. Finally the line-focus microscope was used to demonstrate how the Rayleigh velocity and attenuation can be used to characterise the microstructure of ceramics and ceramic composites. 38587
Keisuke Honda
Nondestructive evaluation of pack-diffusion coatings: A review and preliminary results
Multi-color displaying ultrasonic microscope
Argonne National Laboratory, Argonne, Illinois (United States), ANL-FE- 87-7, DE88-005491, 36 pp. (Dec. 1987) This report reviews potential nondestructive evaluation (NDE) methods for coatings applicable to heat recovery systems of coal gasifiers. The review focuses mainly on aluminized, chromized, or simultaneously aluminized/chromized coatings that are produced by pack-diffusion processes on low-alloy steels. Nondestructive evaluation is required for characterization of as-received coatings relative to acceptance criteria, and for inspection of field fabrication and repairs. A candidate NDE technique must ideally be capable of detecting fine cracks, inclusions, voids, and AI/Cr concentration profiles. In general, a spatial resolution on the order of tens of micrometers is required. The candidate NDE methods reviewed are thermal wave imaging, scanning acoustic microscopy, ultrasonic backscattered surface waves, eddy-current testing, and X-ray fluorescence.
38417
38773
Klima, S.J.; Baaklini, G.Y.
Ultrasonic characterization of structural ceramics Materials Analysis by Ultrasonics - Metals, Ceramics, Composites. Edited by A. Vary. pp. 112-118. Noyes Data Corporation, New Jersey, United States (1987). Ultrasonic velocity and attenuation measurements were used to characterize density and microstructure in monolithic silicon nitride and silicon carbide. Research samples of these structural ceramics exhibited a wide range of density and microstructural variations. It was shown that bulk density variations correlate with and can be estimated by velocity measurements. Variations in microstructural features such as grain size or shape and pore morphology had a minor effect on velocity. However, these features had a pronounced effect on ultrasonic attenuation. The ultrasonic results are supplemented low- energy radiography and scanning laser microscopy. 38752
Generazio, E.R.; Roth, D.J.
Quantitative flaw characterization with scanning laser acoustic microscopy Materials Analysis by Ultrasonics - Metals, Ceramics, Composites. Edited by A Vary. pp. 331-348. Noyes Data Corporation, New Jersey, United States (1987) Surface roughness and diffraction are two factors that have been observed to affect the accuracy of flaw characterization with scanning laser acoustic microscopy. Inaccuracies can arise when the surface of the test sample is acoustically rough. It is shown that, in this case, Snell's law is no longer valid for determining the direction of sound propagation within the sample. This paper investigates the relationship between the direction of sound propagation within the sample, the apparent flaw depth, and the sample's surface roughness. Diffraction effects can mask the acoustic images of minute flaws and make it difficult to establish their size, depth, and other characteristics. It is shown that for Fraunhofer diffraction conditions the acoustic image of a subsurface defect corresponds to a two-dimensional Fourier transform. Transforms based on simulated flaws are used to infer the size and shape of the actual flaw. 38723
Ohno, M.
Resolution of scanning acoustic microscope in sub-surface imaging Japanese Journal of Applied Physics, Vol. 27, No. 5, pp. 734-737 (May 1988)
44
U.S. Patent No. 4,674,333 (23 Jun. 1987) An ultrasonic microscope which displays results in two colours has been developed. Ultrasonic waves are bounced of the object to be inspected and detected using a receiving element. The transmission and reception elements shift with respect to the object in two dimension and resultant signals are displayed in two colours on a cathode ray tube.
Kushibiki, J.; lshikawa, T.; Chubachi, N.
Precise measurement of film thickness by line-focus-beam acoustic
microscope Ultrasonics International 87, Conference Proceedings, London (United Kingdom), 6-9 Jul. 1987. pp. 291-296. Butterworth and Co. (Publishers) Ltd., Guildford, Surrey (1987) The line-focus-beam (LFB) acoustic microscope has been applied to film thickness measurements utilizing the velocity dispersion of leaky waves. The measurement method is investigated theoretically and experimentally, taking typical configurations of an isotropic sample of Au-film on fused quartz and an anisotropic sample of Au-film on silicon wafer. In general, there exist multiple leaky modes in the measurement for such layered media, so that a proper mode selection should be made to get higher accuracy. The thickness resolution of 2 angstroms is achieved for a 3000 angstrom Au-film deposited on fused quartz. For the anisotropic sample, it is also shown that the LFB system is much superior in quantitative measurements to the conventional point4ocus- beam (PFB) system.
Kolodziejczyk, E.; Fernandez-Graf, M.R.; Saurel, J.M.; Fryder, V.; Saied, A.; Attal, J.; Rey, V.
38416
Acoustic microstructure of green coffee Ultrasonics International 87, Conference Proceedings, London (United Kingdom), 6-9 Jul. 1987. pp. 284-290. Butterworth and Co. (Publishers) Ltd., Guildford, Surrey (1987) The rapid visualization of the actual microstructure of biologic specimens is of high interest and is now rendered feasible on the intact sample by acoustic microscopy. Nevertheless, practical applications of this method are still limited and relatively little has been done to explore its potential. As an example, we describe here the use of acoustic microscopy as a rapid and efficient method for the study of plant microstructure. 38415
Chen, C.H.; Meyyappan, A.; Wade, G.
Limited angle planar diffraction tomography: A first-order solution Ultrasonics International 87, Conference Proceedings, London (United Kingdom), 6-9 Jul. 1987. pp. 277-283. Butterworth and Co. (Publishers) Ltd., Guildford, Surrey (1987) In this paper, we present a first-order analysis of image reconstruction using limited-angle data. A difference-equation technique is used to obtain the solution. The range of incident angles over which useful projection data are not available is employed as a parameter. We show precisely how the expected mean-squares error increases as the range of incident angles decreases. 38387
Addison, R.C. Jr.," Somekh, M.; Rowe, J.M.; Briggs, G.A.D.
Characterization of thin-film adhesion with the scanning acoustic microscope An International Symposium on Pattern Recognition and Acoustical
NDT International February 1990