Power spectral density of the simulated micro-roughness structure, as a function of spatial frequency f_r. The frequency domain is restricted to f_l = 1/2s_A = 2.70 × 10⁴ m⁻¹ – for N = 2¹³ and s_A = 18.5 μm. The red line shows the model curve , with our selected A, B, and C parameters. Light gray: radial cut of one random realization 𝒫_h. The dark gray line shows the average of 100 random realizations.