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

Abstract

The present invention is to provide a synthetic quartz glass body having a high light transmittance. The present invention provides a synthetic quartz glass body having pores in a surface part thereof.

1 . A synthetic quartz glass body which has pores in a surface part thereof. 
     
     
         2 . The synthetic quartz glass body of  claim 1 , wherein the pores in the surface part have been formed by physical or chemical etching. 
     
     
         3 . The synthetic quartz glass body of  claim 2 , wherein the pores in the surface part have been formed by etching with a fluorinating agent. 
     
     
         4 . A synthetic quartz glass body which has a surface part having a gradient fluorine atom concentration decreasing from the surface toward the depth direction. 
     
     
         5 . A synthetic quartz glass body which has pores in a surface part thereof, the surface part having a gradient fluorine atom concentration decreasing from the surface toward the depth direction. 
     
     
         6 . The synthetic quartz glass body of  claim 1 , which satisfies 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°.   
     
     
         7 . The synthetic quartz glass body of  claim 4 , having a fluorine concentration in an outermost surface of from 1,000 ppm by weight to 2% by weight. 
     
     
         8 . The synthetic quartz glass body of  claim 4 , wherein when depth from the surface and the logarithm of fluorine concentration at a given depth from the surface are plotted along the X axis and the Y axis, respectively, to obtain a linear relational expression concerning Y value and X value by the least square method, then the depth from the surface at a fluorine concentration of 100 ppm by weight as obtained using the linear relational expression is 500 nm or smaller. 
     
     
         9 - 16 . (canceled) 
     
     
         17 . The synthetic quartz glass body of  claim 4 , which satisfies 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°.