The irradiance (power per unit area) of a laser oscillating in the TEM mode can be expressed as
where is the maximum irradiance of the beam and is a parameter that describes the width (i.e., the spatial extent) of the beam. You can show that when , the locations at which are . Show that when and , the irradiance is and show that the above expression for the irradance is equivalent to
where the “scaled variables” and are defined as . We can relate this expression to the total power transmitted by the beam:
(a) Assume mW and mm to generate a line plot of the irradiance on the vertical axis versus on the horizontal axis for for different values of and .
(b) Repeat (a) but now plot the irradiance divided by the maximum irradiance for that particular value of (in other words, plot ) versus on the horizontal axis. Comment on the resulting plot.