Figuring

Abstract: The computer controlled polisher uses a small, rotating tool which travels over the workpiece surface. By accurately controlling the velocity of the tool, a prescribed amount of material may be removed at each point on the surface. The use of a small tool permits rapid figuring of aspheric surfaces for lightweighted workpieces. The computer controlled polisher was optimized with regard to tool configurations, dwell times, scanning paths, and operating parameters. The unit has successfully fabricated several different workpieces including a mirror with a 1/80-wave rms departure, where a wave is 0.6328 μm.

Abstract: Aspheric reflective optics are becoming more and more important for synchrotron radiation source and X-ray applications. The manufacture of such highly precise optical surfaces requires deterministic ultra-precision machining technologies. The article focuses on the present status of development of ion beam finishing technology and of atmospheric plasma jet technology in Leibniz Institute of Surface Modification (IOM). The basics of the ion beam and the plasma jet processing technologies and the respective equipment and components developed or being under development for production purposes will be presented together with results on the ion beam figuring (IBF), ion beam smoothing (IBS), and the deep figuring and figure correction using atmospheric plasma jet machining (PJM) technique, respectively. Using IBF and IBS, we achieve nanometer and sub-nanometer accuracies over nearly the entire spectrum of spatial surface wavelength on a variety of materials. PJM technique has been developed to obtain high removal rates especially on silicon-based materials. Removal depths of some 10 μm can easily be achieved. The article gives an outlook to future activities on developments of the techniques with respect to advanced X-ray optics.

Abstract: Metrology plays an important role in surface figuring with subnanometer accuracy. We have developed relative angle determinable stitching interferometry for the surface figuring of elliptical mirrors, in order to realize hard x-ray nanofocusing. In a stitching system, stitching angles are determined not by the general method using a common area between neighboring shots, but by the new method using the mirror’s tilt angles measured at times when profile data are acquired. The high measurement accuracy of approximately 4nm (peak-to-valley) was achieved in the measurement of a cylindrical surface having the same curvature as the elliptically designed shape to enable hard x-ray nanofocusing.