Image Contrast Processes in Thermal and Thermoacoustic Imaging

Murphy, J. C.; Maclachlan, J. W.; Aamodt, L. C.

doi:10.1109/t-uffc.1986.26865

Cited by 28 publications

(7 citation statements)

References 68 publications

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“…The contrast in photoacoustic imaging [4][5][6] can be due to inhomogeneity of optical parameters ͑of complex refractive index n͒ controlling the amount and the spatial distribution of the absorbed optical energy, due to inhomogeneity of physical parameters ͑of thermal conductivity , for example͒ controlling transport of the deposited energy inside the medium and due to inhomogeneity of material parameters ͑such as bulk thermal expansion coefficient ␤, bulk elastic modulus B, and heat capacity C, for example͒ controlling the emission of coherent acoustic waves. We are not considering here the experimental situations where the contrast is due to inhomogeneity of material properties controlling sound propagation outside the generation region 7,8 where photoacoustic conversion is used just as a source of acoustic waves for otherwise ordinary acoustic imaging and microscopy. In the most common form of photoacoustic imaging the light intensity is modulated monochromatically and the acoustic signal is detected at fundamental frequency 0 .…”

Section: Introductionmentioning

confidence: 99%

Nonlinear frequency-mixing photoacoustic imaging of a crack: Theory

Gusev

Chigarev

2010

Journal of Applied Physics

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This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to ] IP: 136.165.238.131 On: Sun, 21 Dec 2014 04:55:22 124905-2 V. Gusev and N. Chigarev J. Appl. Phys. 107, 124905 ͑2010͒ [This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to ] IP: 136.165.238.131 On: Sun, 21 Dec 2014 04:55:22 124905-3 V. Gusev and N. Chigarev J. Appl. Phys. 107, 124905 ͑2010͒ [This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to ] IP: 136.165.238.131 On: Sun, 21 Dec 2014 04:55:22 124905-4 V. Gusev and N. Chigarev J. Appl. Phys. 107, 124905 ͑2010͒ [This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to ] IP: 136.165.238.131 On: Sun, 21 Dec 2014 04:55:22 124905-5 V. Gusev and N. Chigarev J. Appl. Phys. 107, 124905 ͑2010͒ [This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to ] IP: 136.165.238.131 On: Sun, 21 Dec 2014 04:55:22 124905-6 V. Gusev and N. Chigarev J. Appl. Phys. 107, 124905 ͑2010͒ [This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to ] IP: 136.165.238.131 On: Sun, 21 Dec 2014 04:55:22 124905-8 V. Gusev and N. Chigarev J. Appl. Phys. 107, 124905 ͑2010͒ [This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to ] IP: 136.165.238.131 On: Sun, 21 Dec 2014 04:55:22 124905-9 V. Gusev and N. Chigarev J. Appl. Phys. 107, 124905 ͑2010͒ [This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to ] IP: 136.165.238.131 On: Sun, 21 Dec 2014 04:55:22 124905-10 V. Gusev and N. Chigarev J. Appl. Phys. 107, 124905 ͑2010͒ [This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to ] IP: 136.165.238.131 On: Sun, 21 Dec 2014 04:55:22 124905-11 V. Gusev and N. Chigarev J. Appl. Phys. 107, 124905 ͑2010͒ [This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to ] IP: 136.165.238.131 On: Sun, 21 Dec 2014 04:55:22 124905-13 V. Gusev and N. Chigarev

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Section: Introductionmentioning

confidence: 99%

Nonlinear frequency-mixing photoacoustic imaging of a crack: Theory

Gusev

Chigarev

2010

Journal of Applied Physics

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“…The variation of the specimen current with frequency is not shown in these figures but was found to be independent of frequency for the range of frequencies used in this work, revealing no dependence of the kind observed in the acoustic case. The origin of the frequency dependence for the ion-acoustic signal has not been established but it is noteworthy that a similar frequency dependence has been observed in electron-acoustic imaging and is correlated with the visibility of lateral s-tructures such as grain boundaries or closed cracks [10]. There it was suggested that two generation mechanisms for acoustic waves in solids exist because of the presence of two frequency regimes.…”

Section: Methodsmentioning

confidence: 89%

“…Recently, ion sources have been used for excitation [7,8,9] and share some imaging features in common with laser and electron sources. All three types of sources have the ability to detect buried defects in opaque solids and to locate tightly closed cracks [10]. However, the fundamental physical mechanisms of signal generation and image contrast vary to some extent based on the source and, in particular, on the physics of ionacoustic signal generation process.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Oxygen on the Ion-Acoustic Signal Generation Process

Satkiewicz

Murphy

Maclachlan

et al. 1987

Review of Progress in Quantitative Nondestructive Evaluation

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“…Photothermal techniques [7][8][9] are a rapidly expanding research field for the inspection of industrial materials. The part is surface-heated by a laser or similar radiative source and the temperature evolution is monitored to evaluate the thermal parameters of the material such as the thermal diffusivity.…”

Section: Description Of the Methodsmentioning

confidence: 99%

A rapid test for evaluating the degree of cure in CFRP composites

Krapez

Cielo

Cole

et al. 1987

Journal of Thermal Analysis

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A noncontact optothermal method is described for possible application to routine industrial evaluation of the degree of cure in polymeric composites. The surface of the part is heated by a laser beam or other radiative source while its temperature evolution is continuously monitored with an infrared detector. A strong exothermal peak is observed when the material is partially or totally uncured. Changes in the signal shape related to variations of the part geometry or environmental conditions are minimized by a differential approach comparing subsequent heat cycles on the same area. Results obtained with cured or uncured graphite-epoxy prepreg sheets are presented.Quality control of composite materials and structures is a very active research field [1,2]. Graphite-epoxy composites are particularly subject to strict inspection procedures because of their increasing utilization as primary structures in safetysensitive fields such as in the aircraft industry. The mechanical properties of carbonfiber-reinforced-plastics (CFRP) structures are much affected by the degree of cure of the resin matrix both before and after processing. Before processing, the slightly precured prepreg sheets which are shipped to the manufacturer in refrigerated cells are normally inspected to verify, that the required pre-cure level has not been exceeded [3]. After lay-up and autoclave curing, the degree of polymerization must be sufficiently high to assure the required mechanical performance.A number of approaches are possible to evaluate the degree of polymer cure, including spectroscopic, calorimetric, mechanical, electromagnetic or ultrasonic methods [1,4,5], the most widely used being the spectroscopic and the thermal techniques. Infrared spectroscopy can provide quantitative data concerning the amount of unreacted epoxy groups. For best results measurements must be made in transmission and, in the case of cured composites, this requires destruction (grinding) of the sample. The diffuse reflectance method has the advantage of being noncontact and nondestructive, but is of limited value for quantitative work [4].

show abstract

Image Contrast Processes in Thermal and Thermoacoustic Imaging

Cited by 28 publications

References 68 publications

Nonlinear frequency-mixing photoacoustic imaging of a crack: Theory

Nonlinear frequency-mixing photoacoustic imaging of a crack: Theory

The Effect of Oxygen on the Ion-Acoustic Signal Generation Process

A rapid test for evaluating the degree of cure in CFRP composites

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