The fabrication of large high-quality diffraction gratings remains one of the most challenging tasks in optical fabrication. Traditional direct-write methods, such as diamond ruling or electron-beam lithography, can be extremely slow and result in gratings with undesired phase errors. Holographic methods, while generally resulting in gratings with smoother phase, frequently require large aspheres and lengthy optical setup in order to achieve desired period chirps. In this paper we describe a novel interference lithography method called scanning-beam interference lithography (SBIL) that utilizes small phase-locked scanning beams to write general periodic patterns onto large substrates. Small mutually coherent beams are phase controlled by high-bandwidth electro-optic components and caused to overlap and interfere, generating a small grating image. The image is raster-scanned over the substrate by use of a high-precision interferometer-controlled air bearing stage, resulting in large grating patterns. We will describe a prototype system in our laboratory designed to write gratings with extremely low phase distortion. The system is being generalized to pattern gratings with arbitrary period progressions (chirps). This technology, with extensions, will allow the rapid, low cost patterning of high-fidelity periodic patterns of arbitrary geometry on large substrates that could be of great interest to astronomers.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.