| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To obtain silica glass free from the deterioration of transmittance of light in vacuum ultraviolet region and having a lifetime prolonged by improving the durability against ultraviolet ray or radiation. <P>SOLUTION: The silica glass consists essentially of silicon oxide SiO<SB>2</SB>and contains transition metals, alkaline earth metals and alkali metals respectively by≤50 ppb, and the vacuum ultraviolet characteristic and radiation resistant characteristic are improved by incorporating OH group by≤100 ppm and controlling dissolved hydrogen to 1×10<SP>17</SP>-1×10<SP>19</SP>molecule/cm<SP>3</SP>and oxygen discharge quantity under vacuum at 1000°C to≤1×10<SP>18</SP>molecule/cm<SP>3</SP>and is further improved preferably by doping 100-1,000 ppm fluorine. <P>COPYRIGHT: (C)2004,JPO</p> |
