Continuous melting of phosphate laser glasses

Continuous melting of phosphate laser glass is being used for the first time to prepare meter-scale amplifier optics for megajoule lasers, a description of the melting process is given. Two key factors in the successful melting of laser glasses are the elimination of damage-causing Pt-inclusions and dehydroxylation of the glass to concentrations less than similar to 100 ppmw OH. Oxidizing conditions using 100% O-2 or O-2 + Cl-2 mixtures (at one atmosphere) can be used to dissolve Pt inclusions and the effects of different gases on the dissolution of Pt-inclusions show the trend O-2 + Cl-2 > O-2 much greater than N-2. The removal of hydroxyl groups is achieved by reactive (O-2 + Cl-2) or non-reactive (O-2) gas bubbling; model calculations are used to simulate this process. (C) 2000 Published by Elsevier Science B.V. All rights reserved.