Patent ID: 7001458
Filing Date: 2006-02-21
Classification: C30B

Abstract:
1. A process for growing optical fluorite crystals, said process comprising: (a) having a furnace having a melting zone and an annealing zone; (b) placing in the furnace a crucible having wherein said crucible and seed crystal unit are placed in the furnace such that the fluorite material to be melted is in the melting zone, and a top portion of the seed crystal within the seed unit is within the melting zone; (c) holding the crucible as described in step (b) in the melting zone for a time for the melt to become homogeneous; (e) moving the crucible and seed crystal unit in a direction such that 10–40% of the seed crystal extends into the melting zone; (f) holding the moved crucible and seed crystal unit in the melting zone for a dime in the range of 10–20 minutes; (g) moving said crucible and seed crystal unit from the melting zone to the annealing zone; and (h) lowering the temperature in a programmed manner to room temperature.