# Laser power inside a vapour cell

I have a laser beam whose power I measured to be x $$\text{mW/cm}^2$$. Furthermore, I measured the beam profile of the laser beam and therefore can estimate its intensity. I shine this laser through a vapour cell filled with Rubidium atoms and after it passed the vapour cell let it reflect by a mirror and pass through the vapour cell again (perfectly collinear). Will the laser power/intensity inside my vapour cell be doubled since there are now effectively two laser beams? Or will there just form a standing wave and the power/intensity are unaffected?

This is relevant since, e.g., the scattering rate in Doppler cooling requires knowledge of the laser intensity "as perceived by the atoms".