Manufacturing process for striae-free multicomponent chalcogenide glasses via convection mixing

A method for making a striae-free chalcogenide glass, comprising:

• loading chalcogenide glass precursors into an ampoule, sealing the ampoule, and placing the ampoule in a furnace, wherein said furnace has an upper furnace element corresponding to a top zone and a lower furnace element corresponding to a bottom zone, and wherein the furnace is fixed without undergoing any rocking or external mechanical agitation;
• heating the ampoule to form a glass melt from the chalcogenide glass precursors, wherein said heating creates a negative temperature gradient between the top zone and the bottom zone, wherein the bottom zone has a higher temperature than the top zone, and wherein said temperature gradient creates convection currents in said glass melt;
• reversing said negative temperature gradient and creating a positive temperature gradient between said top zone and said bottom zone by adjusting said upper furnace element to heat said top zone and adjusting said lower furnace element to cool said bottom zone, wherein said bottom heat zone has a lower temperature than said top heat zone;
• cooling said glass melt while maintaining said positive temperature gradient, wherein during said cooling there are holds at multiple temperatures;
• removing said ampoule from said furnace and water quenching said glass melt.