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Fabrication of single crystal silicon mirror substrates for X-ray astronomical missions

The advancement of X-ray astronomy largely depends on technological advances in the manufacturing of X-ray optics. Future X-ray astronomy missions will require thousands of nearly perfect mirror segments to produce an X-ray optical assembly with < 5 arcsecond resolving capability. Present-day optical manufacturing technologies are not capable of producing thousands of such mirrors within typical mission time and budget allotments. Therefore, efforts towards the establishment of a process capable of producing sufficiently precise X-ray mirrors in a time-efficient and cost-effective manner are needed. Single-crystal silicon is preferred as a mirror substrate material over glass since it is stronger and free of internal stress, allowing it to retain its precision when cut into very thin mirror substrates. This paper details our early pursuits of suitable fabrication technologies for the mass production of sub-arcsecond angular resolution single-crystal silicon mirror substrates for X-ray telescopes.