deletions | additions       diff --git a/The_maximum_displace.tex b/The_maximum_displace.tex  index 7ba4048..3c26077 100644  --- a/The_maximum_displace.tex  +++ b/The_maximum_displace.tex 
...
For elastography measurements, Muthupillai et al. declared that displacements 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 \cite{11937286}, 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 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 removal \cite{8352621}. The linear dependence with laser energy means that shear waves of lower amplitude can 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 optical coherence tomography probe. The laser have also the advantage to be non-contact and totally remote. For example, Li et al. have proposed to induce surface acoustic waves by laser to measure elastic properties of biological thin layers like skin or cornea \cite{li2011elastic}, \cite{li2014laser}. Moreover, the probe used for laser can be made extremely small (smaller than 100 $\mu$m diameter if required), especially if optical fibres are employed. There could be then an interest for endoscopy, by inducing displacement with a simple optic fibre which can be inserted in small intima or vessels. Additionally, the shear wave source emits very weak electromagnetic noise (apart from the laser device itself), so it can be quite convenient for magnetic resonance elastography measurements, which are currently using external drivers or non-magnetic ultrasound probes. Moreover, the laser probe could help to shape precisely the shear wave shape, with focusing capabilities for example (see for example \cite{noroy1993laser}). 
...