Synthetic quartz glass for optical member and its production method
View Patent ↗A synthetic quartz glass for an optical member which is free from compaction and rarefaction is obtained. A synthetic quartz glass for an optical member to be used for an optical device employing a light having a wavelength of at most 400 nm and at least 170 nm as a light source, which contains substantially no oxygen excess defects, dissolved oxygen molecules nor reduction type defects, which has a chlorine concentration of at most 50 ppm and a OH group concentration of at most 100 ppm, and which contains oxygen deficient defects within a concentration range of at most 5×10 14 defects/cm 3 and at least 1×10 13 defects/cm 3 . The fluorine concentration is preferably at most 100 ppm.
1. A synthetic quartz glass for an optical member to be used for an optical device employing a light having a wavelength in range of 170 nm to 400 nm as a light source, said synthetic quartz glass comprises (i) substantially no oxygen excess defects no dissolved oxygen molecules, and (ii) oxygen deficient defects within a range of at least 1×10 13 defects/cm 3 and at most 5×10 14 defects/cm 3 least,
wherein a concentration of an OH group is most 100 ppm and a concentration of a chlorine is at most 10 ppm, and
the ratios of the scattering peak intensity I 495 at 495 cm −1 and the scattering peak intensity I 606 at 606 cm−1, to the scattering peak intensity I 440 at 440 cm −1 in the laser Raman spectrum, I 495 /I 440 and I 606 /I 440 are at most 0.585 and at most 0.136, respectively.
2. The synthetic quartz glass according to claim 1 , comprising substantially no reduction type defects attributable to SiH.
3. The synthetic quartz glass according to claim 2 ,which has a fluorine concentration of at most 100 ppm.
4. The synthetic quartz glass according to claim 2 , comprising hydrogen molecules within a range of from 5×10 15 molecules/cm 3 to 1×10 19 molecules/cm 3 .
5. The synthetic quartz glass according to claim 1 , wherein the total content of alkali metals, alkaline earth metals and transition metals in the synthetic quartz glass is at most 100 ppb.