| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To obtain a synthetic quartz glass substrate having a high annealing point (a temperature at which the viscosity of the glass is equivalent to 10<SP>13</SP>poises), and excellent thermal resistance, and preventing optical fog form generating. <P>SOLUTION: In the synthetic quartz glass substrate the halogen content is less than 10 ppm, the OH group content is less than 100 ppm, the heavy metal and alkali metal content in total is less than 1 ppm, the annealing point is more than 1050°C and the double refraction within the substrate is less than 0.5 nm/cm. <P>COPYRIGHT: (C)2003,JPO</p> |
