Copper-contaning silica glass, method for producing the same, and xenon flash lamp using the same

Abstract

It is an object of the present invention to provide a copper-containing silica glass which emits fluorescence having a peak in a wavelength range of from 520 nm to 580 nm under irradiation of ultraviolet light with a wavelength of 400 nm or less, and which is excellent in long term stability even in the high output use. The copper-containing silica glass is made to have copper of from 5 wtppm to 200 wtppm, which emits fluorescence having a peak in a wavelength range of from 520 nm to 580 nm under irradiation of ultraviolet light with a wavelength ranging from 160 nm to 400 nm, and in which an internal transmittance per 2.5 mm thickness at a wavelength of 530 nm is 95% or more.

1 . A copper-containing silica glass having copper of from 5 wtppm to 200 wtppm, which emits fluorescence having a peak in a wavelength range of from 520 nm to 580 nm under irradiation of ultraviolet light with a wavelength ranging from 160 nm to 400 nm, wherein an internal transmittance per 2.5 mm thickness at a wavelength of 530 nm is 95% or more. 
   
   
       2 . The copper-containing silica glass according to  claim 1 , wherein the total cross-sectional area of bubbles each having a diameter of 0.08 mm or more which are contained in 100 cm 3  thereof is 0.1 mm 2  or less. 
   
   
       3 . The copper-containing silica glass according to  claim 1 , wherein viscosity log η at a temperature of 1,280° C. is of from 11 to 12.5. 
   
   
       4 . The copper-containing silica glass according to  claim 1 , wherein each of the concentrations of Na, K, Mg, Ca and Al is less than 1 wtppm. 
   
   
       5 . The copper-containing silica glass according to  claim 1 , wherein the OH group concentration is of from 0.1 wtppm to 500 wtppm. 
   
   
       6 . A xenon flash lamp using a silica glass tube which is produced with the copper-containing silica glass according to  claim 1 . 
   
   
       7 . A method of producing the copper-containing silica glass according to  claim 1  comprising the steps of:
 a) depositing silica particles produced by hydrolyzing silicon compounds with an oxyhydrogen flame to obtain silica porous body,   b) immersing the silica porous body obtained in the step a) in a solution containing copper ions, keeping it for a predetermined time, and then removing it from the solution to dry, and   c) vitrifying the dried silica porous body under a weak reducing atmosphere at a temperature ranging from 1,350° C. to 1,600° C.   
   
   
       8 . The method of producing the copper-containing silica glass according to  claim 7 , wherein the weak reducing atmosphere is a vacuum atmosphere in a graphite furnace. 
   
   
       9 . The method of producing the copper-containing silica glass according to  claim 7 , wherein the weak reducing atmosphere is a mixed gas atmosphere of hydrogen and an inert gas which contains 5 vol % or less of hydrogen. 
   
   
       10 . The method of producing the copper-containing silica glass according to  claim 7 , wherein the step b) is followed by performing unstuffing. 
   
   
       11 . The method of producing the copper-containing silica glass according to  claim 7 , wherein in the step c) the silica porous body is heated at a temperature ranging from 900° C. to 1,250° C. before vitrifying.