Hi!. I´m modeling a gaussiam beam. I found that considering the electric field distribution of Gaussian laser pulses along the axis of propagation, we can write the intensity as: Where [itex]y = I_l[/itex] R is the power is the power reflection coefficient [itex]y = w_0[/itex] is the beam waist radius at [itex]y = z=0[/itex] [itex]t_l[/itex] is the laser pulse duration But, I don´t now what represents [itex]r[/itex] in the formula. I find that r is the distance from the center axis of the beam, but i don´t understand this explanation. Thank you very much.