Elastic Emission Machining of Optics for Structural Biology Imaging

As Free-Electron Laser and diffraction-limited storage ring X-ray light sources have come into their own in the past few years, the need for highly precise X-ray mirrors is becoming more and more apparent. These brighter X-ray light sources are being held back by the mirrors that are used, both in the availability of these optics, as well as their manufacturability. There are very few methods that are capable of polishing mirrors to atomic accuracy and is something that is both difficult and unreliable to manufacture. To address the shortcomings in reliability in manufacturing, OptiPro proposes to adapt current machinery built at OptiPro into Elastic Emission Machining equipment. Elastic Emission Machining (EEM) has been used for decades in Japan for the precise manufacturing of X-ray mirrors. This process submerges the mirror and tooling in a slurry solution made up of ultra-fine particles. These particles are then accelerated to the surface of the substrate, causing a strong bond to take place. This bond, specifically, is stronger than the covalent bonds of the substrate atoms. The fluid flow then creates a sheer force, causing the particle, and its attached substrate atom, to be removed from the surface. This atomic level of material removal is ideal for the final figuring of X-ray mirrors and can create both geometrically and crystallographically perfect surfaces. In Phase II, we propose to utilize our Phase I testbed based on the OptiPro OptiSonic 1230, to serve as the motion control system for the EEM process. Novel tooling, a new spindle design, a slurry containment tank, and advanced fluid jet polishing system will all be designed and implemented into the platform to complete its conversion into a machine capable of EEM. This testbed is capable of polishing optics up to 500 mm in length, and we mean to leverage that working envelope to polish optics ranging from 200mm to 500mm in length with differing geometries to include planar, spherical/cylindrical, off-axis ellipsoids and diaboloidal surfaces, encompassing any geometry of Kirkpatrick-Baez and Wolter Mirrors. X-ray mirrors can range from 100mm to over 1 meter in length and the machining platform is capable of handling optics up to 1200 mm in length. The proposed manufacturing system has already proven successful in Phase I and will significantly advance the state of the art in polishing techniques and is a crucial piece when considering the future of X-ray light sources and beam-line optics. While the X-ray mirror industry will benefit from EEM technology, they are not alone. Many industries are now requiring as close to geometrically and crystallographically perfect surfaces to include the semiconductor industry, astronomical telescope elements, defense equipment, and high-power laser systems. The proposed manufacturing testbed, manufacturing process, and ultimately finished X-ray mirrors will be designed, constructed, and tested at OptiPro facilities in Ontario, NY, just outside of Rochester. The project is expected to last 24 months.