= Power spectrum of surface height
{title2=$S_h(q)=\int C_h(\xi)e^{-iq\xi}d\xi$}
For a real zero-mean stationary height process, its <power spectrum of surface height> is the <Fourier transform> of the height <covariance function>. It is even and nonnegative, and $\sigma^2=(2\pi)^{-1}\int S_h(q)dq$. More general stationary processes have a spectral measure rather than a density. Weighted spectral moments control the existence of boundary derivatives and second-order mean scattering corrections.
Back to article page
