HIGH PURITY FUSED SILICA WITH LOW ABSOLUTE REFRACTIVE INDEX

摘要

PROBLEM TO BE SOLVED: To provide fused silica glass which has excellent birefringence and resistance to laser damage.;SOLUTION: The fused silica article has combined concentration of protium-containing hydroxy groups and deuteroxy groups less than about 10 ppm, and also has an absolute refractive index of less than or equal to 1.560835 at a wavelength of about 193.368 nm. A method of annealing fused silica glass is also provided. The method comprises the steps of: heating provided fused silica glass to a first temperature above the anneal point; cooling the fused silica glass to a second temperature below the strain point at a progressively decreasing cooling rate that is less than the anneal rate, wherein the progressively decreasing cooling rate is lower than the anneal rate of the fused silica glass; and cooling the fused silica glass from the second temperature to room temperature at a third cooling rate.;COPYRIGHT: (C)2010,JPO&INPIT