Molding glass by using air bearings is a promising procedure for inexpensive and high precision glass shaping. Thin glass sheets are sandwiched between air bearings and pushed flat while being thermally cycled. In this study, a novel device for shaping glass is created and tested using 0.5 mm thick, 100 mm round, Schott D263 wafers. Numerous samples were shaped with varying values for bearing-to-glass gap and maximum temperature, and were measured with a Shack Hartmann metrology tool. Glass was shaped with bearing-to-glass gaps of >50 μm, 36±2.5 μm, and 30.5±2.5 μm. The best peak-to-valley (P-V) flatness achieved is 6.7/3.6±0.5 μm for front/back of the glass sheet, using a gap of 36±2.5 μm. The average steady-state P-V achieved is 12 μm. Using the same device parameters, the best repeatability achieved over the whole 100 mm wafer is 2.7±0.5 μm P-V and 9.5 arcseconds RMS slope error. When looking at 60 mm sections, the repeatability improves to <1 μm P-V and 5±0.5 arcsec.
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Edward Sung ; Brandon Chalifoux ; Mark L. Schattenburg and Ralf K. Heilmann
Non-touch thermal air-bearing shaping of x-ray telescope optics
", Proc. SPIE 8861, Optics for EUV, X-Ray, and Gamma-Ray Astronomy VI, 88610R (September 26, 2013); doi:10.1117/12.2026100; http://dx.doi.org/10.1117/12.2026100