<math> \hat{\mathcal{K}}(\omega)\hat{\psi}(\omega)=\mathcal{F}\left\{\mathcal{K}(\mathbf{y})\right\}\mathcal{F}\left\{\psi(\mathbf{y})\right\}=\zeta^2\hat{\psi}(\omega). | <math> \hat{\mathcal{K}}(\omega)\hat{\psi}(\omega)=\mathcal{F}\left\{\mathcal{K}(\mathbf{y})\right\}\mathcal{F}\left\{\psi(\mathbf{y})\right\}=\zeta^2\hat{\psi}(\omega). |