Problem 1: Compute the power densities for the medically realistic situations described below:

(a) Photocoagulation of the retina using 500μm-diameter spots and a laser power of 200 milliwatts.
(b) Photovaporization of opacities within the eye using 50μm-diameter spots and laser power setting of 2 watts.
(c) Compare these two power densities by computing the ratio between them, and explain why your answer makes physical sense given the uses to which the lasers are applied.