| 摘要 |
PURPOSE:To well observe the state of a material held at a low temperature by filling up a barrel with a dry gas having a boiling point lower than the temperature of the use to prevent the occurrence of congelation or dew condensation in the barrel. CONSTITUTION:A barrel 11 is evacuated through a gas charging hole 17 after adjusting the lens position to a prescribed position, and dry gaseous nitrogen is flowed into the barrel 11 through the gas charging hole 17 to fill up the barrel 11 with gaseous nitrogen, and the gas charging hole 17 is sealed up. In this case, the environment of the use is an LNG, and nitrogen is selected as the charging gas which is not liquefied at the temperature of this LNG. A fiber scope constituted in this manner is used to observe the image of a sample 32 arranged in the bottom part of a low-temperature vessel 30 filled up with the LNG 31.
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