The authors have developed a very simple and rapid x-ray technique for the characterisation of superlattices. The method relies on continuous photographic recording of diffracted x-rays while scanning the superlattice sample through a small range of angles. They have worked up to the seventh-order diffraction spot with relatively short (1 h) exposures. A series of exposures of increasing duration permits the estimate of relative diffraction spot intensities and ultimately provides a measure of the range of interface roughness and/or intermixing between the layers forming the superlattice. The technique is demonstrated with an evaporated amorphous Ge-SiO superlattice, for which a roughness length of approximately 0.6 nm was found.