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For elastography measurements, Muthupillai et al. declared that 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, 10 ns, 200 mJ for a 5-mm diameter beam, is about fifty times higher than the 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 tatoo removal \cite{8352621}.As their is a linear dependence with laser energy, lower amplitude 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 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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