Solve the below problem:
Q: The intensity (mW/mm2) of a laser beam on a surface theoretically follows a bivariate normal distribution with maximum intensity at the center, equal variance s in the x and y directions, and zero covariance. There are several definitionsfor the width of the beam. One definition is the diameter at which the intensity is 50% of its peak. Suppose that the beamwidth is 1.6 mm under this definition. Determine s. Also determine the beam width when it is defined as the diameter where the intensity equals 1/ e2 of the peak.