| 摘要 |
PROBLEM TO BE SOLVED: To stably grow a metal fluoride single crystal by suppressing the fluctuation of radiation state to the single crystal being pulled while maintaining a melt at a shallow state wherein the formation of scattering bodies is suppressed. SOLUTION: The metal fluoride single crystal (10) is pulled by using a double-structured crucible consisting of an outer crucible (4) and an inner crucible (5) and while maintaining such a state that the single crystal (10) is surrounded up to its upper end part by a cylindrical member (25) which is arranged in such a manner that its lower end part is situated in a part lower than the upper end part of the inner crucible (5). Then, the storing depth of the inner crucible (5) against the outer crucible (4) is made deeper in response to the decrease of a melt (7) of the raw material metal fluoride housed in the inner crucible (5) accompanied by the growth of the single crystal (10). Thereby, the melt (7) housed in the outer crucible (4) is supplied into the inner crucible (5) so that the amount of the melt (7) in the inner crucible (5) is maintained within a certain range. COPYRIGHT: (C)2008,JPO&INPIT
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