Continuous melting of phosphate laser glass is being used for the first tim
e to prepare meter-scale amplifier optics for megajoule lasers, a descripti
on of the melting process is given. Two key factors in the successful melti
ng of laser glasses are the elimination of damage-causing Pt-inclusions and
dehydroxylation of the glass to concentrations less than similar to 100 pp
mw OH. Oxidizing conditions using 100% O-2 or O-2 + Cl-2 mixtures (at one a
tmosphere) can be used to dissolve Pt inclusions and the effects of differe
nt 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 reac
tive (O-2 + Cl-2) or non-reactive (O-2) gas bubbling; model calculations ar
e used to simulate this process. (C) 2000 Published by Elsevier Science B.V
. All rights reserved.