Patent ID: 6376401
Filing Date: 2002-04-23
Classification: C03B,C03C

Abstract:
An ultraviolet ray-transparent optical glass material comprising a synthetic silica glass produced from a silicon compound having a high degree of purity by a soot method in which the silicon compound is flame-hydrolyzed, the resultant soots are accumulated to form a porous silica preform body and the porous silica preform body is converted to a transparent glass by heating in a gas atmosphere consisting of nitrogen, helium, a mixture of carbon monoxide with nitrogen or a mixture of nitrogen with helium, said synthetic silica glass containing substantially no impurity other than hydroxyl group, and having a difference between highest and lowest fictive temperatures of the glass of 50Â° C. or less, and a transmittance of ultraviolet rays at a wave length of 157 nm through an optical path having a length of 10 mm of 60% or more.