Third harmonic imaging using pulse inversion

Rasmussen, Joachim; Du, Yigang; Jensen, Jørgen Arendt

doi:10.1109/ultsym.2011.0563

Cited by 4 publications

(2 citation statements)

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“…On the contrary, THG across the stress-free boundary of a solid is different from SHG. That is, the two third harmonic waves reflected from the stress-free boundary constructively interfere with each other, and the resulting third harmonic component accumulates as the propagation distance increases [ 11 , 12 ]. Therefore, it is possible to realize THG measurements in the pulse-echo mode.…”

Section: Thickness Resonant Transducer For Thg Measurement In Pulse-e...mentioning

confidence: 99%

“…Unlike the behavior of second harmonics [ 9 , 10 ], the behavior of the third harmonic at the stress-free boundary can be treated like a continuously transmitted wave propagating twice the sample thickness because there is no phase difference between the two third harmonics after reflection [ 11 , 12 ]. The resulting third harmonic component accumulates in proportion to the propagation distance.…”

Section: Introductionmentioning

confidence: 99%

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Highly Sensitive Detection of Microstructure Variation Using a Thickness Resonant Transducer and Pulse-Echo Third Harmonic Generation

et al. 2023

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In nonlinear ultrasound testing, the relative nonlinear parameter is conveniently measured as a sensitive means of detecting and imaging overall variation of microstructures and damages. Compared to the quadratic nonlinear parameter (β′), the cubic nonlinear parameter (γ′), calculated as the third harmonic amplitude divided by the cube of the fundamental amplitude, has generally a higher value, providing better sensitivity in nonlinear parameter mapping. Since the third harmonic amplitude is about two orders of magnitude lower than the fundamental amplitude, efficient excitation and highly sensitive reception of third harmonic is very important. In this paper, we explore an odd harmonic thickness resonant transducer that meets the requirements for pulse-echo third harmonic generation (THG) measurements. We also address the problem of source nonlinearity that may be present in the measured amplitude of the third harmonic and propose a method to properly correct it. First, we measure γ′ for a series of aluminum specimens using the through-transmission method to observe the behavior of γ′ as a function of specimen thickness and input voltage, and examine the effects of various corrections such as attenuation, diffraction and source nonlinearity. Next, we apply the odd harmonic resonant transducer to pulse-echo THG measurements of precipitation heat-treated specimens. It is shown that such transducer is very effective in generation and detection of fundamental and third harmonics under finite amplitude toneburst excitation. The highly sensitive detectability of γ′ are presented as a function of aging time, and the sensitivity of γ′ is compared with that of β′ and β′2.

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Section: Thickness Resonant Transducer For Thg Measurement In Pulse-e...mentioning

confidence: 99%