Pol Grasland-Mongrain edited Dependance with beam power.tex  about 8 years ago

Commit id: cbb316a6e1a742bd6f2932b32a813ba342a67b0f

deletions | additions      

       

The Finally, the  dependence of thegenerated  shear wave amplitude with versus  laser energy was finally quantitavely  investigatedquantitatively  by increasing the laser beam energy from 10 to 200 mJ. Amplitude have been Amplitudes were  averaged over four experiments for each energy level and successive energy levels were randomly chosen to avoid any time-related bias and bias. In addition,  impact location was changed after each laser emission to avoid any potential local degradation of the medium. Shear wave amplitude was measured as the mean square amplitude at t = 1 ms of the displacement between 0 and 10 mm of the medium surface, which was  an arbitrary location where shear waves had demonstrated  high amplitudes. Resulting measurements are illustrated in Figure \ref{figDepEnergy}. Two linear dependencies are observed: one from 10 to 40 mJ, with a slope of 1.05 (R$^2$ = 0.87), and one from 30mJ  to 200 mJ, with a slope of 2.18 (R$^2$ = 0.97). This is in accordance with the theory which presents a linear dependence of the that  displacement with is linearly dependent on  energy at low energy, energies,  i.e. in the thermoelastic regime as described in equation \ref{eq:deplThermoApprox}, and a quadratic dependence but quadratically dependent  at high energy, energies,  i.e. in the ablative regime as described in equation \ref{eq:deplAblaApprox}.