| 摘要 |
PROBLEM TO BE SOLVED: To provide a method and device for heat treatment of an optical fiber preform capable of preventing corrosion of a furnace body and contamination of a furnace core tube, and capable of precisely controlling a pressure difference between inside and outside of the furnace core tube, and also capable of using on pressurized or depressurized condition other than normal pressure condition. SOLUTION: This device is constituted of a 1st room TR wherein the heat treatment is to be performed, and a 2nd room HR provided outside of and separated from the 1st room, wherein a heater is provided, a 1st evacuation tube 7, a 2nd evacuation tube 8, and a 3rd evacuation tube 9a to which the 1st evacuation tube and the 2nd evacuation tube are joined, wherein a 1st regulation means MV 17 which regulates at least the pressure in the 1st room or gas flow of the 1st room is provided in the 1st evacuation pipe, and a 2nd regulation means (MV 19, 15) which regulate the pressure or gas flows of the 1st and 2nd rooms in the 3rd evacuating tube.
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