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For elastography measurements, Muthupillai et al. declared that displacements a displacement  of a few hundreds of nanometers should be sufficient to perform shear wave elastography \cite{7569924}. However, displacements of 5 to 20 $\mu$m are usually required, which is slightly higher than the maximum displacement observed here (about 2 $\mu$m in the chicken breast sample). The maximum laser beam energy used in the samples, 532 nm, 20 ns, 200 mJ for a 5-mm diameter beam, is about fifty times the higher thanthe  maximum exposure permissible as given by the current American National Standard Institute (Z136.1-2000) for skin \cite{ANSIZ1361}, but is also about five to ten times lower than the typical energy used for skin tatto tatoo  removal \cite{8352621}. The As their is a  linear dependence with laser energy means that shear waves of energy,  lower amplitude can shear waves should also  be observed. More efficient displacement observation methods could be performed with better displacement tracking algorithms, and devices with an higher spatial resolution, like ultrasound probe of higher frequency or an a  optical coherence tomography probe. Shear wave frequency in elastography ranges typically between 50 and 500 Hz, with higher frequency meaning better spatial resolution. The experiments demonstrated that these frequencies can be reached, although the mechanism explaining this particular frequency is not clear yet. 
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