Glass

特許 係属中 A method for producing an ultra-low expansion glass, comprising: preparing a TiO2-SiO2 glass ingot having a desired TiO2 concentration; cutting out a sample from the TiO2-SiO2 glass ingot; measuring the OH concentration C(OH), TiO2 concentration C(TiO2) and fictive temperature (TF); calculating the zero-CTE temperature (T) based on the C(OH), C(TiO2) and (TF) having been measured above.