Crystal growth and annealing method and apparatus
US6309461A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Jun 7, 1999 |
| Grant date | Oct 30, 2001 |
| Priority date | — |
| Expiry date | Jun 7, 2019 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T117/1024
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.