Some additional information: I have attached the design file, and in the attached picture you can see the differences between the reflectivity calculated from an observation area and from an observation point. I am only interested on specular reflectivity
Regarding R from the observation area, I used the power spectrum option and then I calculated Pz normalized to input plane.
Regarding R from the observation point, I calculated the normalized DFT for Ex, Ey, and Ez and then R=(Ex)^2+(Ey)^2+(Ez)^2
Overall the coincidence is acceptable, but the ball should enhance the reflectivity at 0.0165 microns, and it only happens when I calculate R from the observation point. However, when I use the observation area, results are different.
I am lost! Any help would be very welcome!