| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain the subject silica glass member which comprehensively satisfies optical properties including light transmittance, laserproofness, birefringence and homogeneity, SOLUTION: This optical silica glass member for F2 excimer laser transmission is obtained by the following steps: a silicon-contg. compound is subjected to flame hydrolysis in a vapor phase to produce silica microparticles, which are accumulated on a heat-resistant substrate to make a porous preform; the preform is then vitrified to clearness into a transparent vitreous form, from which the objective optical silica glass member is produced; wherein, after forming the porous preform and prior to clearly vitrifying it, the porous preform is subjected to OH group-diminishing treatment, oxygen deficiency removal treatment and fluorine doping treatment to bring the fluorine concentration and OH group concentration of the resultant porous preform to 0.1-2.0 mol and <=5 ppm, respectively.</p> |
