Pol Grasland-Mongrain edited Biological tissue.tex  over 8 years ago

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The sample was then replaced by a similar phantom except that cellulose particles were used instead of graphite particles: thus, the phantom presented a weak optical absorption but a comparable speckle pattern. A black disk of variable diameter was painted on a surface of the phantom at the laser beam impact location, to control the absorption area. Paint thickness was higher than 500 $\mu$m. The amplitude of the induced shear waves versus black disk diameter in the second phantom is illustrated in Figure \ref{figDepTache}. \ref{figDepTache}-(A). Displacements maps at t = 1.0, 1.5, 2.0 and 2.5 ms for a black paint disk of 4 mm of diameter are illustrated in Figure \ref{figDepTache}-(B).  We observe a linear relationship between shear wave amplitude and black disk diameter, with a correlation coefficient of 0.9281. We can deduce from this graph that the displacement is mostly due to the absorption of the shear wave by the paint, which is sufficient to induce shear waves. Moreover, the displacement is displacements are  similar as ablative regime with the graphite sample: involved phenomenons are expected to be identical.