| CPC C30B 15/10 (2013.01) [C03B 20/00 (2013.01); C03C 19/00 (2013.01); C30B 29/06 (2013.01); F27B 14/10 (2013.01); G01N 21/3563 (2013.01); G01N 33/386 (2013.01); C03B 19/095 (2013.01)] | 5 Claims |

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1. An infrared transmissivity measurement method of a quartz glass crucible,
in which the quartz glass crucible includes
a transparent layer made of quartz glass that does not contain bubbles,
a bubble layer formed outside the transparent layer and made of quartz glass containing bubbles, and
a semi-molten layer formed outside the bubble layer and made of raw material silica powder solidified in a semi-molten state,
the infrared transmissivity measurement method comprising:
a step of processing an outer surface of the quartz glass crucible formed by the semi-molten layer to remove a part of the semi-molten layer to form at least one recess in the semi-molten layer as a semi-molten layer removed portion such that a surface roughness of the semi-molten layer removed portion is lower than a surface roughness of the outer surface, wherein the semi-molten layer removed portion is surrounded by the semi-molten layer; and
a step of measuring an infrared transmissivity of the quartz glass crucible based on infrared light passing through the semi-molten layer removed portion.
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