Abstract: Disclosed is a method for treating glass and crystalline inorganic materials whereby metal contamination during such process is inhibited. Such process includes treating the material in the presence of a purifying atmosphere comprising a cleansing gas. The process is especially advantageous for treating high purity fused silica glass for use in advanced lithographic devices.

Abstract: Disclosed are synthetic silica glass body with a birefringence pattern having low fast axis direction randomness factor and glass reflow process. The glass reflow process comprises steps of: providing a glass tube having a notch; and thermally reflowing the glass tube to form a glass plate. The process can be advantageously used to produce fused silica glass plate without observable striae when viewed in the direction of optical axis. Also disclosed are optical members comprising the fused silica glass body and a process for reflowing glass cylinders.

Abstract: Disclosed are refractory body and refractory vessel for reforming or reflowing glass materials. The refractory body and vessel have gas venting channels, including surface grooves and/or vias formed on the surface in contact with the glass during high temperature treatment thereof. The refractory body and vessel are particularly advantageous for reflowing fused silica glass at an elevated temperature such as above 1700° C.