Graphite heating furnace
AssigneeFurukawa Electric Co., Ltd.
InventorTadashi TAKAHASHI
Life of this patent
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Abstract
A gas supplying unit supplies a nitrogen gas into a furnace body of a graphite heating furnace in which at least a part of the furnace body is formed with a graphite. An exhausting unit exhausts a gas inside the furnace body to outside the furnace body. A dew-point temperature of the nitrogen gas supplied into the furnace body is equal to or lower than −80° C. A pressure inside the furnace body is equal to or higher than 140 Pa with respect to an atmospheric pressure outside the furnace body.
Claims13
(canceled)
A method of producing an optical fiber preform, comprising:
- forming an optical fiber porous preform;
- dehydrating and sintering the optical fiber porous preform by using a graphite heating furnace of which at least a part of a furnace body is formed with a graphite, wherein the graphite heating furnace includes a reaction container and a furnace body which surrounds the reaction container and in which a heater is displaced;
- and
- supplying a nitrogen gas that has a dew point temperature that is equal to or lower than −80° Celsius into the furnace body and exhausting a gas inside the furnace body by discharging at least a part of the gas inside the furnace body directly to an atmosphere surrounding an outside of the furnace body in the dehydrating and sintering, wherein
- a pressure inside the furnace body is equal to or higher than 140 pascals with respect to an atmospheric pressure of the atmosphere outside the furnace body.
A method of producing an optical fiber preform, comprising:
- forming an optical fiber preform;
- elongating the optical fiber preform by using a graphite heating furnace of which at least a part of a furnace body is formed with a graphite, wherein the graphite heating furnace includes a reaction container and a furnace body which surrounds the reaction container and in which a heater is displaced;
- and
- supplying a nitrogen gas that has a dew point temperature that is equal to or lower than −80° Celsius into the furnace body and exhausting a gas inside the furnace body by discharging at least a part of the gas inside the furnace body directly to an atmosphere surrounding an outside of the furnace body in the elongating, wherein
- a pressure inside the furnace body is equal to or higher than 140 pascals with respect to an atmospheric pressure of the atmosphere outside the furnace body.
A method of producing an optical fiber comprising:
- forming an optical fiber preform;
- drawing the optical fiber preform to an optical fiber by using a graphite heating furnace of which at least a part of a furnace body is formed with a graphite, wherein the graphite heating furnace includes a reaction container and a furnace body which surrounds the reaction container and in which a heater is displaced;
- and
- supplying a nitrogen gas that has a dew point temperature that is equal to are lower than −80° Celsius into the furnace body and exhausting a gas inside the furnace body by discharging at least a part of the gas inside the furnace body directly to an atmosphere surrounding an outside of the furnace body in the drawing, wherein
- a pressure inside the furnace body is equal to or higher than 140 pascals with respect to an atmospheric pressure of the atmosphere outside the furnace body.
Dependencies are inferred from the claim text.