deletions | additions       diff --git a/When_a_laser_beam_of__1.tex b/When_a_laser_beam_of__1.tex  index 75b1973..7c45360 100644  --- a/When_a_laser_beam_of__1.tex  +++ b/When_a_laser_beam_of__1.tex 
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I=(1-R)I_0 \exp(- \gamma r)  \label{eq:opticalIntensity}  \end{equation}  where $R$ is the reflexion coefficient of the medium (typically less than a few pourcents for a black mat medium such as the one used here, so can be neglected), $I_0=\frac{d E}{Sdt}$ $I_0=\frac{1}{S}\frac{d E}{dt}$  the incident intensity distribution at the surface and $\gamma$ the absorption coefficient of the medium. %A measurement of the fraction of light which go through different thicknesses of the medium, cut by a microtome, indicates that $\gamma \approx$ 10$^4$ m$^{-1}$ in our sample, meaning that most of the radiation is absorbed in the first hundred of micrometers.  %Even if the sample is mainlyeFor low concentration medium, $\gamma$ is hard to calculate in our case, as the sample is composed of different materials, but the graphite, even in low concentration, absorbate much more than other components, so we can approximate $\gamma \approx \gamma_{graphite}$. For graphite particles of 1.85 $\mu$m at a concentration of 10 g.L$^{-1}$, the order of magnitude of $\gamma$ is 10$^4$ m$^{-1}$, meaning that most of the radiation is absorbed in the first hundred of micrometers of sample.  This is quite higher than metals where the radiation is absorbed within a few nanometres. 
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