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Crystal growth and annealing method and apparatus

United States Patent Application

20020011202
A1
View the Complete Application at the US Patent & Trademark Office
Sandia National Laboratories - Visit the Intellectual Property Management and Licensing Website
A method and apparatus for producing crystals that minimizes birefringence even at large crystal sizes, and is suitable for production of CaF.sub.2 crystals. The method of the present invention comprises annealing a crystal by maintaining a minimal temperature gradient in the crystal while slowly reducing the bulk temperature of the crystal. An apparatus according to the present invention includes a thermal control system added to a crystal growth and annealing apparatus, wherein the thermal control system allows a temperature gradient during crystal growth but minimizes the temperature gradient during crystal annealing. An embodiment of the present invention comprises a secondary heater incorporated into a conventional crystal growth and annealing apparatus. The secondary heater supplies heat to minimize the temperature gradients in the crystal during the annealing process. The secondary heater can mount near the bottom of the crucible to effectively maintain appropriate temperature gradients.
Gianoulakis, Steven E. (Albuquerque, NM), Sparrow, Robert (North Brookfield, MA)
09/ 952,172
September 15, 2001
[0001] This invention was made with Government support under Contract DE-AC04-94AL85000 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.