Imaging of human tooth using ultrasound based chirp-coded nonlinear time reversal acoustics

This Letter presents a series of time reversal experiments conducted on the surface of a fused silica glass block. Four different time reversal techniques are compared using three different imaging conditions. The techniques include two classical time reversal experiments: one with a pulse waveform source and one with an impulse response generated from a chirp signal. The other two techniques utilize the deconvolution, or inverse filter, signal processing methods for obtaining the signals to back propagate using a pulse waveform and an impulse response from a chirp. The max-in-time, symmetry, and energy current imaging conditions are compared.

Section: Introductionmentioning

confidence: 99%

Comparison and visualization of focusing wave fields from various time reversal techniques in elastic media

Anderson

Ulrich

Bas

2013

“…TR in solid media has found application in nondestructive evaluation, to localize and characterize cracks in mechanical parts, 3,4 to estimate shear elasticity of materials, 5 to locate landmines, 6 and for imaging of human teeth. 7 It has also found application in the localization of seismic events 8,9 and localization in touch panel applications. 10,11 TR generally consists of two phases.…”

Section: Introductionmentioning

confidence: 99%

Time reversal reconstruction of finite sized sources in elastic media

Anderson

Griffa²,

Ulrich³

et al. 2011

The ability of the time reversal process to reconstruct sources of finite size relative to a wavelength is investigated. Specifically the quality of the spatial reconstruction of a finite sized source will be presented through the use of time reversal experiments conducted on an aluminum plate. The data presented in the paper show that time reversal can reconstruct a source equally well regarding less of its size, when the source is a half wavelength or less in size. The quality of spatial reconstruction when the source is larger than a half wavelength progressively decreases with the size of the source.

“…23 We apply the preceding signal processing approaches in combination with time reversal 28 (TR), an approach termed time reversed elastic nonlinearity diagnostic (TREND), part of the tool box known as time reversal nonlinear elastic wave spectroscopy and developed over the last decade as a new approach to detect defects in industrial materials, 29,30 landmine location, 27 rock characterization, 31 and more recently for tooth imaging. 32 Time reversal provides the means to focus energy at a desired location with large amplitudes, allowing very localized detection of nonlinear properties. Moreover, as high strain amplitude is only located at the focal point, weaker excitation at the source transducers is required to obtain an equivalent strain amplitude compared to unfocused methods; this reduces unwanted nonlinearities coming from the source or from associated source electronics.…”

Section: Introductionmentioning

confidence: 99%

Time reversed elastic nonlinearity diagnostic applied to mock osseointegration monitoring applying two experimental models

Rivière

Haupert

Laugier

et al. 2012

This study broadens vibration-like techniques developed for osseointegration monitoring to the nonlinear field. The time reversed elastic nonlinearity diagnostic is applied to two mock models. The first one consists of tightening a dental implant at different torques in a mock cortical bone; the second one allows one to follow glue curing at the interface between a dental implant and a mock jaw. Energy is focused near the implant interface using the time reversal technique. Two nonlinear procedures termed pulse inversion and the scaling subtraction method, already used successfully in other fields such as contrast agents and material characterization, are employed. These two procedures are compared for both models. The results suggest that nonlinear elasticity can provide new information regarding the interface, complementary to the linear wave velocity and attenuation. The curing experiment exhibits an overall low nonlinear level due to the fact that the glue significantly damps elastic nonlinearity at the interface. In contrast, the torque experiment shows strong nonlinearities at the focus time. Consequently, a parallel analysis of these models, both only partially reflecting a real case, enables one to envisage future in vivo experiments.