Method for determining the eccentricity of an optical fiber and method for manufacturing an optical fiber

Abstract

To determine a state of eccentricity of a coating of an optical fiber from a glass fiber even if the coating is thin.SOLUTION: A method for an optical fiber having a glass fiber and a coating formed around the glass fiber that determines a state of eccentricity of the coating from the glass fiber causes a control part to perform: an acquisition step of acquiring measurements of outer diameter at a plurality of positions along a length of the optical fiber; a calculation step of calculating a standard deviation based upon the plurality of measurements of the outer diameter of the optical fiber; and a determination step of determining the state of eccentricity of the coating based upon the standard deviation.SELECTED DRAWING: Figure 2

Claims

1. A method for determining the eccentricity of the coating on a glass fiber in an optical fiber having a glass fiber and a coating formed around the glass fiber, The outer diameter of the optical fiber is 160 μm or more and 200 μm or less. An acquisition step of obtaining measurements of the outer diameter at multiple locations along the longitudinal direction of the optical fiber, A calculation step of calculating the standard deviation based on multiple measurements of the outer diameter of the optical fiber, A determination step of determining the eccentricity of the coating based on the standard deviation, This is done by the control unit. The acquisition step involves acquiring the measured values ​​of the outer diameter of the optical fiber, which are measured at predetermined time intervals during the manufacturing of the optical fiber. The calculation step involves calculating a first standard deviation based on a plurality of measurements of the outer diameter of the optical fiber measured in a first period, and calculating a second standard deviation based on a plurality of measurements of the outer diameter of the optical fiber measured in a second period that is later than the first period. The aforementioned determination step, based on a comparison of the first standard deviation and the second standard deviation, determines that the eccentricity is large if the second standard deviation is larger than the first standard deviation. The aforementioned determination step is an eccentricity determination method in which, if the standard deviation is 0.3 μm or more, it is determined that the eccentricity of the coating exceeds the allowable range.

2. The eccentricity determination method according to claim 1, wherein the acquisition step acquires the measured value of the outer diameter of the optical fiber measured every 20 ms for a total of 15 seconds during the manufacturing of the optical fiber.

3. A method for manufacturing optical fibers, comprising forming glass fibers by heating and melting an optical fiber base material and drawing it, and then forming a coating around the glass fibers with a resin coating portion, The outer diameter of the optical fiber is 160 μm or more and 200 μm or less. A measurement step of measuring the outer diameter of the optical fiber at predetermined time intervals during the manufacturing of the optical fiber, A calculation step of calculating the standard deviation based on multiple measurements of the outer diameter of the optical fiber, Based on the standard deviation, the step of tilting the resin coating portion, Includes, The calculation step involves calculating a first standard deviation based on a plurality of measurements of the outer diameter of the optical fiber measured in a first period, and calculating a second standard deviation based on a plurality of measurements of the outer diameter of the optical fiber measured in a second period that is later than the first period. The step of tilting the resin coating portion is performed if the second standard deviation is greater than the first standard deviation, A method for manufacturing an optical fiber, wherein the step of tilting the resin-coated portion is performed when the standard deviation is 0.3 μm or more.

4. The step of tilting the resin coating portion is, A method for manufacturing an optical fiber according to claim 3, wherein if the standard deviation calculated based on a plurality of measurements of the outer diameter of the optical fiber, including at least one measurement taken after tilting the resin-coated portion, is greater than the standard deviation calculated based on a plurality of measurements of the outer diameter of the optical fiber taken before tilting the resin-coated portion, the resin-coated portion is tilted in a different direction than the previous time.

5. The method for manufacturing an optical fiber according to claim 3, wherein the measurement step involves measuring the outer diameter of the optical fiber every 20 ms for a total of 15 seconds during the manufacturing of the optical fiber.

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