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公开(公告)号:US4918520A
公开(公告)日:1990-04-17
申请号:US185894
申请日:1988-04-25
CPC分类号: C30B13/30 , Y10T117/1004
摘要: A device for use in a monocrystal producing apparatus based on the FZ method and designed to detect a crystallization interface (20) between a melt (16) and a monocrystalline rod (12) even if the luminous line of the crystallization interface is partly curved downward. This device samples a series of luminance signals from the side of the melt to the side of the monocrystalline rod along a sensing line intersecting the crystallization interface, thereby successively outputs a series of sampled luminance signals (Sj), determines a value as a reference level (S.sub.0) relative to this specific level of the luminance signals, e.g., a peak value thereof, and discriminates the crystallization interface when one of the series of sampled luminance signals exceeds the reference level. A pixel position corresponding to this discrimination is determined as a pixel position corresponding to the crystallization interface.