Optical fiber drawing methods and drawing furnaces
AssigneeFurukawa Electric Co., Ltd.
InventorsNobuaki Orita, Takashi Suzuki, Yoshiyuki Sakata
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Abstract
Drawing methods and drawing furnaces for drawing an optical fiber with small non-circularity by simple drawing system are provided. An optical fiber preform is received into a muffle tube and heated by a primary heater placed to surround the muffle tube. The optical fiber preform is heated such that a starting position of a meniscus portion is higher in its position than the top of the primary heater, wherein the meniscus portion is created at the bottom portion of the optical fiber preform.
Claims2
A method of drawing an optical fiber from an optical fiber preform, wherein the optical fiber preform is received into a muffle tube and heated by a heater placed to surround the muffle tube, the method comprising:
- heating the optical fiber preform such that a starting position of a meniscus portion is higher in its position than the top of the heater, the heater being an uppermost heater, wherein the meniscus portion is created at the bottom portion of the optical fiber preform,
- wherein the heater contributes to formation of the meniscus portion,
- wherein the optical fiber preform is made of silica glass and a diameter of the optical fiber preform is equal to or greater than 100 mm,
- wherein an outer diameter of the meniscus portion in a longitudinal direction includes a convex shape, a concave shape, and an inflection point between the convex shape and the concave shape, and
- wherein the optical fiber preform is heated such that the maximum absolute value of a rate of change in the outer diameter of the meniscus portion of the optical fiber preform in the longitudinal direction at the inflection point is equal to or less than 0.8.
Dependencies are inferred from the claim text.