| 摘要 |
PROBLEM TO BE SOLVED: To drastically improve the stress birefringence of a crystal, to make the refractive index highly homogeneous over the whole volume of the crystal, and to provide the crystal especially as a crystal used for an optical element. SOLUTION: The method for producing a low stress, large volume crystal having prescribed dimensions confined in diameter and height, low stress birefringence and a homogeneous refractive index is constituted of (a) a process for growing a crystal having dimensions larger than prescribed dimensions from a melt, (b) a process for cooling the crystal having the large dimensions obtained in the process (a), (c) a process for tempering the crystal having the large dimensions obtained in the process (a), and (d) a process for removing the edge parts of the crystal so that the crystal has the prescribed dimensions confined in diameter and height by cutting each of the diameter and the height of the crystal by at least 5% after cooling in the process (b) and tempering in the process (c). In this method, tempering of the crystal is not performed after removing the edge parts. COPYRIGHT: (C)2005,JPO&NCIPI
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