This Small Business Innovation Research Phase I project seeks to revolutionize the manufacture of ultra-high precision, x-ray diffraction gratings. Mechanically ruled, x-ray gratings are used mainly at synchrotron radiation facilities, where they define the wavelength of x-rays used for chemical analysis and imaging studies in a wide range of disciplines including photovoltaics, electronic materials, catalysis, structural biology, and environmental science. These facilities serve a wide variety of industries and academic disciplines. While the technology to make such gratings, based on an instrument called a "ruling engine", was invented in the U.S., commercial manufacturing moved abroad decades ago to Japan and Europe. Previous feasibility studies suggest a potentially revolutionary new technology for manufacturing x-ray gratings: using a scanning probe platform based on piezoelectric motion stages, the ability to rule high-quality grating lines over length scales of 100 microns has been demonstrated. The objective of this project is to build a manufacturing platform to scale up this approach to areas of 75 square centimeters, which is sufficient for commercial gratings. The final objective is to deliver a full-sized prototype to a partner facility which will perform testing on the resulting structure.
The broader impact/commercial potential of this project is that, in the past three years, a crisis has occurred in the x-ray grating market. The only two global suppliers of mechanically-ruled gratings ceased to take orders, either because their technology was obsolete or because of severe infrastructure problems. This vanishing of world capacity has taken place when demand for x-ray gratings is at an all-time high and growing. Extensive communication with management at several synchrotron facilities has established that the average facility currently has an order backlog of six gratings. There are seventy such facilities in the world, which implies a near-term revenue potential of approximately $21 million. The goal is to capture the entire market and bring this area of manufacturing back to the U.S. This market aside, this project has the potential to enable new technologies based on the ability to realize customized optical wave fronts, as the proposed approach allows grating lines to be curved into arcs or ellipses, providing lateral focusing, or written with topological defects that create electromagnetic vortices with high angular momentum. These unexplored capabilities could find use in inertial confinement fusion, x-ray telescopes, or the wider market of optical gratings.
The goal of this Phase I SBIR project was to demonstrate the feasibility of a new technique to revolutionize the manufacture of ultrahigh precision, x-ray diffraction gratings. Mechanically ruled x-ray gratings, which define the wavelength of x-rays, are required at synchrotron radiation facilities, where x-ray imaging is used for chemical analysis and elucidating the structure of materials. Such imaging studies are essential to the development of improved photovoltaics and electronic materials and to better understanding of catalysis, structural biology, and environmental science. While the technology to make such gratings, based on an instrument called a "ruling engine," was invented in the United States, commercial manufacturing of these gratings moved abroad decades ago to Japan and Europe. In 2009–2011, however, the only two world suppliers of mechanically ruled gratings, Zeiss (Germany) and Hitachi (Japan), ceased to take orders, leaving synchrotron laboratories around the world no source for these essential components. Zeiss closed their grating division, which used decades-old technology, and Hitachi’s machine was damaged in the Tohoku earthquake and was not replaced. While several European companies provide plastic holographic gratings, they are inferior to mechanically ruled metal gratings. This vanishing of world production capacity has taken place when demand for x-ray gratings is at an all-time high and growing. Inprentus, Inc. has demonstrated the feasibility of mechanically ruling blazed x-ray diffraction gratings using two atomic force microscopes (AFMs), operated in tandem, to replace the mechanical ruling engine. Several prototype gratings were fabricated using this new technique and were evaluated for commercial viability by the Center for X-Ray Optics at Lawrence Berkeley National Laboratory, where they were found to meet specifications and outperform holographic gratings. A U.S. patent has been filed on this technique, and a second patent will be filed in 2014. The company sold its first grating to Brookhaven National Laboratory, which will be delivered by December 1, 2013. During this project, the company also worked with Delaware Diamond Knives, to develop the diamond AFM tips used to rule the gratings. This project has created new infrastructure having unique capabilities for manufacturing diffractive optics and has returned the manufacturing of high-quality blazed diffraction gratings to the United States from Germany and Japan. In addition, two graduate students have been trained in AFM scribing techniques and mechanical lithography. This project has enabled the creation of a new, manufacturing-based startup company in central Illinois. This new company will be a valuable asset to many commercial sectors that use high-precision diffractive optics.
