Specific Process Knowledge/Back-end processing/Laser Micromachining Tool/fluence

Fluence definition

The fluence produces by a laser is, by definition, the energy delivered by a laser pulse ($E_{pulse}$) per surface unit ($S$) and it is given in J/cm2.

The function $E_{pulse}$ is defined as :

$E_{pulse}={\frac {\overline {P}}{f}}\,$

Where ${\overline {P}}$ (average power) and is measured with the laser sensor power measurement (see laser manual section 5.3) and the repetion rate ($f$) is set in the parameter file under " laser frequency".

The fluence is therefore determinate as such :

$Fluence={\frac {E_{pulse}}{S}}\,$

The theoretical spot sizes ($S$) can be found here