| 摘要 |
<p>PROBLEM TO BE SOLVED: To produce the silica glass having a UV absorption edge of a shorter wavelength and yet excellent UV resistance and radiation resistance. SOLUTION: In this production, pure silica glass samples A to C are prepared and each of the samples A to C is irradiated with an ArF excimer laser beam and correlation of the degrees of reduction in UV transmissivity with the number of irradiation shots of each of the samples A to C is measured and plotted. At this time, the plot for the sample A shows almost no reduction in transmissivity even at the time of increasing the number of irradiation shots. The sample A having such excellent UV resistance and radiation resistance, can be obtained by positively generating many structural defects in the quartz glass in the UV irradiation treatment and removing the generated defects with heat treatment of the irradiated quartz glass, to widen the average bond angle of the Si-0-Si network in the quartz glass after the heat treatment as compared with that before the heat treatment, to allow structural relaxation of the irradiated quartz glass to progress, to form structurally stable quartz glass and to inhibit defects due to the UV irradiation from being generated in the quartz glass. Thus, since the enhancement of UV resistance and radiation resistance of the quartz glass of the sample A is not due to the increase in hydroxyl group concn. in the quartz glass, the wavelength of the UV absorption edge does not become longer.</p> |
