| 摘要 |
There is provided a substrate material for an optical component for X-rays of wavelength lambda<SUB>R</SUB>. The substrate includes (a) a glass phase made of amorphous material having a positive coefficient of thermal expansion, and (b) a crystal phase including microcrystallites having a negative coefficient of thermal expansion and a mean size of less than about 4 lambda<SUB>R</SUB>. The substrate material has a stoichiometric ratio of the crystal phase to the glass phase such that a coefficient of thermal expansion of the substrate material is less than about 5x10<SUP>-6 </SUP>K<SUP>-1 </SUP>in a temperature range of about 20 °C. to 100°C. The substrate material, following a surface treatment, has a high spatial frequency roughness (HSFR) of less than about lambda<SUB>R</SUB>/30 rms.
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