X-ray diffraction from smectic materials in device-like cells is used to determine the layer structure within the cells. The experimental method determines the smectic layer normal orientational distribution as a function of tilt and twist angles within the cell. In a special case where the layer normals are not twisted away from the alignment direction, the chevron structures have been reconstructed from the distributions. The influence of the surface pre-tilt due to the alignment layer, electric fields and skewed alignment layers on the smectic layer normal distributions are reviewed and discussed.