Manufacturing method for optical fiber

Abstract

This method for manufacturing an optical fiber includes: a step for melting an optical fiber preform and drawing an optical fiber; a step for causing the drawn optical fiber to contact a roller that switches the traveling direction of the optical fiber; and a step for measuring the location at which the optical fiber contacts the roller.

Description

Optical fiber manufacturing method

[0001] This disclosure relates to a method for manufacturing an optical fiber. This application claims priority to Japanese Patent Application No. 2023-204611 filed on December 4, 2023, and incorporates by reference the entire contents of said Japanese application.

[0002] Patent Document 1 describes a method for measuring the twist of an optical fiber. In this method, light is irradiated onto the optical fiber from multiple irradiation positions, and the intensity distribution of the light transmitted through the optical fiber is detected at multiple detection positions. The twist of the optical fiber is calculated based on the detected multiple intensity distributions.

[0003] International Publication No. 2023 / 095916

[0004] A method for manufacturing an optical fiber according to one aspect of the present disclosure includes the steps of melting an optical fiber preform and drawing an optical fiber, bringing the optical fiber into contact with a roller that changes the running direction of the drawn optical fiber, and measuring the position at which the optical fiber contacts the roller.

[0005] Fig. 1 is a schematic diagram of a manufacturing apparatus used in a method for manufacturing an optical fiber according to an embodiment. Fig. 2 is a perspective view showing a roller directly below the manufacturing apparatus and an optical fiber of Fig. 1. Fig. 3 is a diagram for explaining the inclination of the roller directly below the manufacturing apparatus of Fig. 2. Fig. 4 is a diagram for explaining a step of measuring the position. Fig. 5 is a diagram for explaining a step of adjusting the position or inclination of the roller.

[0006] Twisted optical fibers can be difficult to handle, so it is necessary to be able to determine the degree of twist in optical fibers.

[0007] An object of the present disclosure is to provide a method for manufacturing an optical fiber that allows the degree of twist in the optical fiber to be determined.

[0008] According to the present disclosure, it is possible to grasp the degree of twist in an optical fiber.

[0009] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described. (1) A method for manufacturing an optical fiber according to one embodiment includes the steps of melting an optical fiber preform and drawing an optical fiber, bringing the optical fiber into contact with a roller that changes the running direction of the drawn optical fiber, and measuring the position at which the optical fiber contacts the roller.

[0010] In the above-described method for manufacturing an optical fiber, the degree of twist in the optical fiber can be determined by measuring the position of the optical fiber that comes into contact with the roller that changes the running direction of the optical fiber.

[0011] (2) In the above (1), the roller may be a roller directly below the optical fiber that changes the running direction of the optical fiber drawn vertically downward. In this case, it is possible to measure the contact position of the optical fiber at the roller directly below the optical fiber, where twisting is likely to occur.

[0012] (3) In the above (1) or (2), the measuring step may measure the relative position of the optical fiber with respect to a reference point of the roller. In this case, by measuring the relative position of the optical fiber with respect to the reference point of the roller, the position of the roller can be measured with higher accuracy.

[0013] (4) In any of the above (1) to (3), the measuring step may measure the positions where the optical fiber contacts the roller at multiple parts. In this case, by measuring the positions where the optical fiber contacts the roller at multiple parts, the degree of twist of the optical fiber can be determined with higher accuracy.

[0014] (5) In any of the above (1) to (4), the method for manufacturing an optical fiber may include a step of adjusting the position or inclination of the roller according to the position measured in the measuring step. In this case, by adjusting the position or inclination of the roller according to the position where the optical fiber contacts, twisting of the optical fiber can be reduced.

[0015] [Details of the embodiments of the present disclosure] Specific examples of the manufacturing method of the optical fiber of the present disclosure will be described below with reference to the drawings. The present invention is not limited to the following examples, but is intended to include all modifications set forth in the claims and within the scope equivalent to the claims. In the description of the drawings, identical or corresponding elements are designated by the same reference numerals, and redundant description will be omitted as appropriate. The drawings may be appropriately simplified or exaggerated for ease of understanding, and dimensional proportions and the like are not limited to those shown in the drawings.

[0016] Fig. 1 is a diagram showing a manufacturing apparatus used in a manufacturing method of an optical fiber according to an embodiment. As shown in Fig. 1, the manufacturing apparatus 1 includes a heating furnace 2, a cooling device 3, a die 4, a resin curing unit 5, a roller 6, a capstan 7, a winding drum 8, and a measuring unit 10. The heating furnace 2, the cooling device 3, the die 4, the resin curing unit 5, the roller 6, the capstan 7, and the winding drum 8 are arranged in this order along the running direction D1 of the optical fiber 12.

[0017] The heating furnace 2 heats the optical fiber preform 11. The optical fiber preform 11 is melted by heating it in the heating furnace 2. An optical fiber 12 is drawn vertically downward from the lower end of the optical fiber preform 11 melted in the heating furnace 2. The cooling device 3 cools the optical fiber 12.

[0018] The die 4 applies a coating resin to the surface of the optical fiber 12. The die 4 is, for example, a jig having a hole in the center through which the optical fiber 12 passes. The die 4 is supplied with liquid coating resin, and applies the coating resin to the surface of the optical fiber 12 that passes through the hole. In this embodiment, the coating resin is an ultraviolet-curable resin. The resin curing unit 5 hardens the coating resin applied to the surface of the optical fiber 12. In this embodiment, the resin curing unit 5 is an ultraviolet irradiation device that hardens the coating resin by irradiating it with ultraviolet light.

[0019] The roller 6 is a roller disposed directly below the optical fiber preform 11. The roller 6 contacts the optical fiber 12 and changes the running direction D1 of the optical fiber 12 from a vertically downward direction to a direction different from the vertically downward direction. The capstan 7 has a function of taking up the optical fiber 12, and the winding drum 8 has a function of winding up the optical fiber 12.

[0020] The measuring unit 10 measures the position where the optical fiber 12 contacts the roller 6. For example, the manufacturing apparatus 1 has a control unit 15 that controls the position or inclination of the roller 6 in accordance with the position of the optical fiber 12 measured by the measuring unit 10. The functions of the measuring unit 10 and the control unit 15 will be described in detail later.

[0021] 2 and 3 are diagrams schematically illustrating the roller 6 and the optical fiber 12. For example, the peripheral surface of the roller 6 has a groove 6b extending along the rotation direction D2 of the roller 6. As an example, the groove 6b is a V-groove (a groove whose cross section including the depth direction has a V-shape). For example, the groove 6b is defined by a pair of inclined surfaces 6d that are inclined with respect to the direction D3 in which the diameter of the roller 6 extends and that are aligned along the direction D4 in which the rotation axis A of the roller 6 extends.

[0022] The optical fiber 12 extending vertically downward from the resin curing portion 5 comes into contact with the groove 6b of the roller 6. When the roller 6 rotates with the optical fiber 12 in contact with the groove 6b, the running direction D1 of the optical fiber 12 is changed from vertically downward to a direction different from vertically downward. As an example, the running direction D1 of the optical fiber 12 is changed obliquely upward.

[0023] For example, the roller 6 has a contact portion 6c with which the optical fiber 12 comes into contact, and the contact portion 6c extends along the rotation direction D2. However, twisting of the optical fiber 12 may occur on the roller 6. For example, when the rotation axis of the roller 6 is perpendicular to the vertical direction, the optical fiber 12 entering the roller 6 comes into contact near the connection point of the pair of inclined surfaces 6d.

[0024] On the other hand, if the direction D3 in which the diameter of the roller 6 extends is inclined with respect to the vertical direction, the optical fiber 12 entering the roller 6 may only come into contact with one of the inclined surfaces 6d. In this case, twisting of the optical fiber 12 may occur at the roller 6. More specifically, when the optical fiber 12 enters the roller 6, it comes into contact with only one of the inclined surfaces 6d, and when the optical fiber 12 exits the roller 6, the optical fiber 12 is located near the connection point of the pair of inclined surfaces 6d. The optical fiber is twisted by the inclined surfaces with which it comes into contact. The greater the inclination of the direction D3 with respect to the vertical direction, the greater the amount of twisting of the optical fiber 12 may become.

[0025] In this embodiment, the measuring unit 10 observes where the optical fiber 12 is in contact with the roller 6. The measuring unit 10 is, for example, a laser measuring instrument. In this case, the measuring unit 10 irradiates the roller 6 and the optical fiber 12 with laser light L. For example, the measuring unit 10 receives light reflected from the roller 6 and the optical fiber 12 in response to the irradiation of the laser light L, and measures the position of the optical fiber 12 on the roller 6 by detecting the distance from the measuring unit 10 to the roller 6 and the optical fiber 12.

[0026] For example, the manufacturing apparatus 1 may have a plurality of measuring units 10. The measuring units 10 may measure the positions at which the optical fiber 12 contacts at a plurality of portions of the roller 6. For example, the measuring unit 10 measures the positions at which the optical fiber 12 contacts at both the upstream end 6 f and the downstream end 6 g of the contact portion 6 c of the roller 6. However, the measuring unit 10 may also measure the position at which the optical fiber 12 contacts at one portion of the roller 6. For example, the measuring unit 10 may measure the position at which the optical fiber 12 contacts at the upstream end 6 f of the contact portion 6 c of the roller 6.

[0027] 4 is a diagram showing an example of the results measured by the measurement unit 10. For example, the results measured by the measurement unit 10 are displayed on the monitor M. In this embodiment, the measurement unit 10 measures the position of the optical fiber 12 with respect to the groove 6b of the roller 6. For example, the measurement unit 10 sets the intersection of the pair of slopes 6d as a reference point P and measures the relative position of the vertex 12b of the optical fiber 12 with respect to the reference point P.

[0028] The vertex 12b is a point on the optical fiber 12 that is located farthest from the X-axis that passes through the reference point P and extends along the direction D4 in which the rotation axis A of the roller 6 extends. For example, the measuring unit 10 may set the Y-axis to a line that passes through the reference point P and is perpendicular to the X-axis, and measure the distance K from the Y-axis to the vertex 12b as the amount of positional deviation of the optical fiber 12. In this case, the magnitude of the distance K can be used to determine the magnitude of the possibility of twisting of the optical fiber 12.

[0029] After the measurement step of measuring the position of the optical fiber 12 in contact with the roller 6, for example, an adjustment step is performed to adjust the position or inclination of the roller 6 in accordance with the position of the optical fiber 12 measured by the measurement unit 10. The adjustment step is performed by the control unit 15. The control unit 15 is connected to the measurement unit 10 and the roller 6 so as to be able to communicate with them.

[0030] The control unit 15 may be configured as a computer system including, for example, a processor such as a CPU (Central Processing Unit), memories such as RAM (Random Access Memory) and ROM (Read Only Memory), input / output devices such as a touch panel, mouse, keyboard, and display, and a communication device such as a network card. The control unit 15 realizes its functions by operating each piece of hardware under the control of the processor based on a computer program stored in the memory.

[0031] 5 is a schematic diagram illustrating the adjustment process. As shown in FIG. 5, the control unit 15 controls the roller 6 to change the position of the roller 6 based on the position of the optical fiber 12 relative to the roller 6 measured by the measurement unit 10. For example, the control unit 15 sends a control signal based on the measurement results by the measurement unit 10 to the roller 6 to adjust the position of the roller 6 in the direction D4 in which the rotation axis A of the roller 6 extends or the inclination of the roller 6. The control unit 15 moves the portion that receives the rotation axis of the roller 6 by outputting a control signal to an actuator that moves the portion that receives the rotation axis of the roller 6.

[0032] For example, the control unit 15 adjusts the position or inclination of the roller 6 so that the point at which the optical fiber 12 first contacts the roller 6 is near the connection point of the pair of inclined surfaces 6 d. By performing this adjustment step, it is possible to reduce the possibility of twisting of the optical fiber 12. However, this adjustment step is not necessary.

[0033] As described above, in the optical fiber manufacturing method according to the embodiment, the measuring unit 10 measures the position of the optical fiber 12 at which it contacts the rollers 6 that change the running direction D1 of the optical fiber 12, thereby making it possible to determine the degree of twist of the optical fiber 12. In this embodiment, the measuring unit 10 makes it possible to observe where the optical fiber 12 contacts the rollers 6. By previously determining the relationship between the contact position of the optical fiber 12 with the rollers 6 and the degree of twist, and then observing the contact position of the optical fiber 12 with the rollers 6 during manufacturing of the optical fiber 12, it is possible to determine the degree of twist of the optical fiber 12.

[0034] As described above, when adjusting the position or inclination of the roller 6 in the adjustment process, the position or inclination of the roller 6 is adjusted according to the position at which the optical fiber 12 comes into contact. This adjustment suppresses twisting of the optical fiber 12, which makes it easier to align the core positions of the optical fiber 12 when splicing the optical fiber 12 when the optical fiber 12 is a multicore fiber. When the optical fiber 12 is a polarization-maintaining fiber, suppressing twisting of the optical fiber 12 can suppress deviation of the polarization plane at the input end from the polarization plane at the output end.

[0035] The above describes an embodiment of the optical fiber manufacturing method according to the present disclosure. However, the present disclosure is not necessarily limited to the above-described embodiment, and various modifications are possible within the scope of the claims.

[0036] In the above-described embodiment, an example has been described in which the measurement unit 10 sets the intersection of the pair of inclined surfaces 6d as the reference point P. However, the reference point P may be located at a position other than the intersection of the pair of inclined surfaces 6d, and the position of the reference point P is not particularly limited.

[0037] In the above-described embodiment, an example has been described in which the measuring unit 10 measures the position of the optical fiber 12 by detecting the distance from the measuring unit 10 to the roller 6 and the optical fiber 12. However, the measuring unit 10 may measure the position of the optical fiber 12 by detecting scattered light or shadow. The measuring unit 10 does not have to be a laser measuring instrument, and may be, for example, a measuring instrument that takes microscopic photographs of the roller 6 and the optical fiber 12. The type of measuring unit 10 is not particularly limited.

[0038] The roller 6 does not need to have the groove 6b. The shape of the roller 6 is not limited to that of the embodiment described above and can be modified as appropriate. In the embodiment described above, the measuring unit 10 measured the contact position of the optical fiber 12 on the roller 6, which is a roller directly below the optical fiber preform 11 and is arranged vertically below the optical fiber preform 11. However, the measuring unit 10 may measure the contact position of the optical fiber 12 on a roller other than the roller directly below the roller. The type of roller to be measured by the measuring unit 10 is not particularly limited.

[0039] DESCRIPTION OF SYMBOLS 1... Manufacturing device 2... Heating furnace 3... Cooling device 4... Die 5... Resin curing section 6... Roller 6b... Groove 6c... Contact section 6d... Inclined surface 6f... Upstream end 6g... Downstream end 7... Capstan 8... Winding drum 10... Measuring section 11... Optical fiber preform 12... Optical fiber 12b... Apex 15... Control section A... Rotation axis K... Distance L... Laser light M... Monitor P... Reference point

Claims

1. A method for manufacturing an optical fiber, comprising the steps of: melting an optical fiber preform and drawing an optical fiber; bringing the optical fiber into contact with a roller that changes the running direction of the drawn optical fiber; and measuring the position at which the optical fiber contacts the roller.

2. The method for manufacturing optical fiber according to claim 1, wherein the roller is a vertically downward roller that changes the running direction of the optical fiber that is pulled out vertically downward.

3. The method of claim 1 or 2, wherein in the measuring step, a relative position of the optical fiber with respect to a reference point of the roller is measured.

4. The method for manufacturing an optical fiber according to any one of claims 1 to 3, wherein in the measuring step, positions at which the optical fiber contacts the roller at multiple portions are measured.

5. A method for manufacturing an optical fiber according to any one of claims 1 to 4, further comprising a step of adjusting a position or an inclination of the roller in accordance with the position measured in the measuring step.

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