NSF/DFG Collaboration Brinksmeier/Riemer/Lucca: "Ultra-Precision Machining and Near Surface Damage Evolution in Single Crystal Fluorides for Advanced Optics"

• Applicant: Dr.-Ing. Oltmann Riemer
• Subject Area: Metal-Cutting and Abrasive Manufacturing Engineering ; Synthesis and Properties of Functional Materials
• Term: from 2017 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 387318746

• Final Report Year: 2023

Final Report Abstract

The overall objective of the research project was to investigate the relationship between optical performance of single crystal calcium fluoride and subsurface damage introduced by diamond machining. Within the project, fixtures were developed, allowing the alignment of specimens and thus enabling planing experiments without prior pre-machining of the specimens. Furthermore, different fixtures were tested for off-axis diamond turning experiments and two pre-machining strategies were developed and applied. These allow the pre-machining of specimens with surface roughness below 1 nm and minimal subsurface damage. Based on the premachining, diamond turning experiments were performed and surface roughness in the low single-digit nm range could be generated. Analyses of the subsurface by means of transmission electron microscopy showed an influence of the crystal lattice in the vicinity to the machined surface, mostly limited to below 110 nm. The alteration of the crystal lattice is indicated by dislocations and a rotation of the crystal lattice in feed direction. The optical properties of the processed samples were characterized by means of UV-Vis measurements. These showed a measurable influence of the processing parameters and the resulting subsurface properties on the transmissivity of the specimens.

Publications

• Development of a manual multiaxes work-piece adjustment system for ultraprecision diamond machining, euspen’s 19th International Conference & Exhibition, 2019, ISBN: 978-0-9957751- 4-5
  H. Shizuka, K. Rickens, O. Riemer & D. A. Lucca
  
• Analysis of surface integrity of orthogonal diamond cut single-crystal Calcium Fluoride for ultraviolet and vacuum ultraviolet wavelength applications, euspen’s 20th International Conference & Exhibition, 2020, ISBN: 978-0-9957751-7-6
  K. Rickens, O. Riemer & D. A. Lucca
  
• Ultra-Precision Machining: Cutting With Diamond Tools. Journal of Manufacturing Science and Engineering, 142(11).
  Lucca, D. A.; Klopfstein, M. J. & Riemer, O.
  
• Influence of clamping technique on the resulting surface roughness in diamond machining of CaF2, euspen’s 22nd International Conference & Exhibition, 2022, ISBN: 978-1-9989991- 1-8
  B. Adam, O. Riemer, K. Rickens, D. A. Lucca & M. Tunesi