Infrared transmissivity measurement method of quartz glass crucible

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.