Shin-etsu Chemical Co., Ltd.

Takashi Koshigai

Hideki Fujii

Kazuya Uchida

A heat treatment apparatus includes: a furnace core tube made of silica glass; a heater provided adjacent to the furnace core tube, the heater heating a heating region; and a moving mechanism supporting a porous glass base material and relatively moving the porous glass base material with respect to the heater in the furnace core tube in a state where the heating region is heated by the heater to make the porous glass base material pass through the heating region. The heat treatment apparatus includes a thin-walled part provided in a region adjacent to a portion located in the heating region in the furnace core tube, the thin-walled part having a thickness of glass less than that of the portion located in the heating region.

Heat treatment apparatus

An optical fiber base material machining method for forming spindle-shaped portions at ends of the optical fiber base material by severing the optical fiber base material after reducing an outer diameter of the optical fiber base material to a predetermined target outer diameter at a predetermined machining position, comprising: reducing the outer diameter to a predetermined intermediate outer diameter between the outer diameter before the machining and the target outer diameter at the machining position; flame polishing a surface of the optical fiber base material in a region including the machining position; and further reducing the outer diameter of the optical fiber base material.

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Gunma-ken, Japan

Takashi Koshigai