| 摘要 |
PURPOSE:To provide the optical fiber drawing furnace having a high effect of preventing heat dissipation. CONSTITUTION:This optical fiber drawing furnace has a heater 3 arranged around an optical fiber preform A to be drawn, a heat resistant heat insulating material 5 which is disposed around this heater 3 and a furnace body 6 which houses the entire part thereof. The heat resistant heat insulating material 5 consists of carbon or a material contg. carbon and its bulk density is highest at the inner end in a diametral direction and is successively lower toward the outer side in the diametral direction. In addition, at least the inner end face 5a in the diametral direction of the outer peripheral surface of the heat resistant heat insulating material 5 is coated with graphite or thermally decomposable carbon. |
