The objective of this appendix is to review a scalar Kirchhoff calculation of diffraction from surfaces composed of sinusoidal reflection gratings by the method outlined in Section 3.2. The surface material is assumed to have a reflectance of 1.0. The examples are important because of the use of Fourier composition to represent more-arbitrary surface topography. Equation (3.28) will be used. This requires that the Fourier transform of E_a(x, y, 0), the incident field in the aperture, be found.