Synthetic quartz glass body, process for producing the same, optical element, and optical apparatus

1. A process for producing a synthetic quartz glass body having a modified surface part which comprises:

bringing a fluorinating agent into contact with a surface of a synthetic quartz glass body in the presence of a solid metal fluoride; and

infiltrating the fluorinating agent to inside the synthetic quartz glass body to modify the surface part.

2. The process for producing a synthetic quartz glass body of claim 1 , wherein the solid metal fluoride comprises one member selected from the group consisting of fluorides of alkali metals, fluorides of alkaline earth metals, and mixtures thereof.

3. The process of claim 1 , wherein the fluorinating agent has a partial pressure in the range of from 1 kPa to 500 kPa.

4. The process of claim 1 , wherein the contacting treatment with the fluorinating agent is conducted until the synthetic quartz glass body being treated comes to satisfy at least one of the following requirements (1) to (6):

(1) the synthetic quartz glass body has a light transmittance of 91.0% or higher when examined with ArF laser light (wavelength: 193 nm) incoming on the surface part at an incidence angle of 0°;

(2) the synthetic quartz glass body has a light transmittance of 92.4% or higher when examined with KrF laser light (wavelength: 248 nm) incoming on the surface part at an incidence angle of 0°;

(3) the synthetic quartz glass body has a light transmittance of 92.5% or higher when examined with the fourth harmonic of YAG light (wavelength: 266 nm) incoming on the surface part at an incidence angle of 0°;

(4) the synthetic quartz glass body has a light transmittance of 93.0% or higher when examined with the third harmonic of YAG light (wavelength: 355 nm) incoming on the surface part at an incidence angle of 0°;

(5) the synthetic quartz glass body has a light transmittance of 89.5% or higher when examined with xenon excimer lamp light (wavelength: 172 nm) incoming on the surface part at an incidence angle of 0°; and

(6) the synthetic quartz glass body has a light transmittance of 93.0% or higher when examined with XeCl laser light (wavelength: 308 nm) incoming on the surface part at an incidence angle of 0°.

5. A process for producing a synthetic quartz glass body having a modified surface part which comprises:

bringing a fluorinating agent into contact with a surface of a synthetic quartz glass body with a gas of the fluorinating agent or a gas mixture obtained by diluting the fluorinating agent with an inert gas; wherein the gas of the fluorinating agent or the gas mixture has a temperature in the range of from −50 to 300° C.; and

infiltrating the fluorinating agent to inside the synthetic quartz glass body to modify the surface part.

6. The process of claim 5 , wherein the fluorinating agent comprises one member selected from the group consisting of elemental fluorine, silicon tetrafluoride, and mixtures thereof.

7. The process of claim 5 , wherein the fluorinating agent has a partial pressure in the range of from 1 kPa to 500 kPa.

8. The process of claim 5 , wherein the contacting treatment with the fluorinating agent is conducted until the synthetic quartz glass body being treated comes to satisfy at least one of the following requirements (1) to (6):

(1) the synthetic quartz glass body has a light transmittance of 91.0% or higher when examined with ArF laser light (wavelength: 193 nm) incoming on the surface part at an incidence angle of 0°;

(2) the synthetic quartz glass body has a light transmittance of 92.4% or higher when examined with KrF laser light (wavelength: 248 nm) incoming on the surface part at an incidence angle of 0°;

(3) the synthetic quartz glass body has a light transmittance of 92.5% or higher when examined with the fourth harmonic of YAG light (wavelength: 266 nm) incoming on the surface part at an incidence angle of 0°;

(4) the synthetic quartz glass body has a light transmittance of 93.0% or higher when examined with the third harmonic of YAG light (wavelength: 355 nm) incoming on the surface part at an incidence angle of 0°;

(5) the synthetic quartz glass body has a light transmittance of 89.5% or higher when examined with xenon excimer lamp light (wavelength: 172 nm) incoming on the surface part at an incidence angle of 0°; and

(6) the synthetic quartz glass body has a light transmittance of 93.0% or higher when examined with XeCl laser light (wavelength: 308 nm) incoming on the surface part at an incidence angle of 0°.