Optical fiber testing method and optical fiber winding device

Abstract

The present application provides an optical fiber testing method and an optical fiber winding device, which can appropriately reproduce the same lateral pressure and slight bending state as in an optical cable in the testing of an optical fiber. The optical fiber testing method takes a second layer optical fiber (51-2) wound on a bobbin (12) as a test object. Further, a third layer optical fiber (51-3) is applied to the second layer optical fiber (51-2) with lateral pressure. The lateral pressure is adjusted by the tension when winding the third layer optical fiber (51-3) on the bobbin. That is, since the lateral pressure is applied to the test object optical fiber from other optical fibers, the same lateral pressure and slight bending state as in an optical cable can be reproduced.

Description

Technical Field

[0001] This invention relates to a fiber optic testing method for testing the optical properties of optical fibers and a fiber optic winding device used in the testing. Background Technology

[0002] Previously disclosed methods involve bundling optical fiber cores into small-diameter, high-density optical fiber cables (see, for example, Patent Document 1). These cables are made into cables by densely bundling the optical fiber cores. This results in a thin and lightweight structure, improving processability and facilitating the construction of economical optical fiber networks. When implementing such cables, the optical fiber design must avoid increasing optical loss due to cable bundling.

[0003] It is known that when an optical fiber is subjected to a certain lateral pressure, an increase in optical loss occurs due to the minute bending of the fiber, known as micro-bending loss. Several methods for testing this lateral pressure-induced micro-bending loss characteristic are disclosed. In these testing methods, Figure 1 (a) is a diagram illustrating the wire mesh method. Figure 1 (b) is a diagram illustrating the sandpaper method.

[0004] Figure 1 The wire mesh method (a) is a method for measuring optical loss by winding the optical fiber 50 of the object to be measured onto a wire mesh 20 pre-wound onto a cylindrical winding tube 10. Additionally, Figure 1 (X) in the figure represents a cross-section of a plane perpendicular to the axial direction of the winding tube (a portion of the surface of the winding tube in the cross-section). Figure 1 In this context, (Y) represents a cross-section of the plane containing the axis of the winding tube (a portion of the surface of the winding tube in the cross-section).

[0005] Figure 1 The sandpaper method of (b) is a method for measuring optical loss by winding the optical fiber 50 of the object to be measured on sandpaper 30 pre-wound on a cylindrical winding tube 10.

[0006] The above methods all involve pressing the optical fiber 50 onto the metal mesh 20 and sandpaper 30 and applying lateral pressure and slight bending to test the micro-bending loss characteristics (for example, see Non-Patent Literature 1).

[0007] Existing technical documents

[0008] Patent Document 1: Japanese International Publication WO / 2010 / 001663

[0009] Non-patent literature

[0010] Non-patent document 1: "An Overview of Macrobending and Microbending of Optical Fibers", Internet URL: https: / / www.corning.com / media / worldwide / coc / documents / Fiber / white-paper / WP1212.pdf, retrieved on May 14, 2021.

[0011] However, according to the technology in Non-Patent Document 1, the loss characteristics vary greatly depending on the diameter of the metal wires and the mesh size of the wire mesh, or the particle size and shape of the sandpaper. Furthermore, the lateral pressure applied to the optical fiber, in the case of a wire mesh, such as... Figure 1 As shown in (a), the conditions are only applied to the surface where the metal mesh and the optical fiber are in contact in an interlaced manner, and are very different from the state of the optical fiber inside the optical cable.

[0012] The same applies when using sandpaper. Figure 1 As shown in (b), the surface of the sandpaper acting only on the optical fiber, which is irregularly in contact with the optical fiber, is under conditions that are very different from the state of the optical fiber inside the cable.

[0013] In other words, according to the technology in Non-Patent Document 1, it is difficult to properly reproduce the same lateral pressure and minute bending conditions as inside an optical cable during optical fiber testing, and it is impossible to compare the relative characteristics of optical fibers under the same test conditions. Therefore, the problem with the technology in Non-Patent Document 1 is that it is difficult to design optical fibers that can suppress the loss of high-density optical cables. Summary of the Invention

[0014] In order to solve the aforementioned problems, the object of the present invention is to provide an optical fiber testing method and an optical fiber winding device that can appropriately reproduce the same lateral pressure and minute bending conditions as those inside an optical cable during optical fiber testing.

[0015] To achieve the above objectives, the optical fiber testing method and optical fiber winding apparatus of the present invention have the function of causing slight bending by applying lateral pressure while making the optical fibers in contact with each other as in the high-density optical cable.

[0016] Specifically, the optical fiber testing method of the present invention is characterized by the following features:

[0017] Three layers of optical fiber are wound around the winding tube;

[0018] When winding the third layer of optical fiber onto the winding tube, a desired tension is applied to the optical fiber that is stronger than the tension applied when winding the first and second layers of optical fiber onto the winding tube; and

[0019] Optical measurements were performed on the optical fiber in the second layer.

[0020] Furthermore, the optical fiber winding apparatus of the present invention includes: a winding tube for winding a supplied optical fiber; a positioning part for winding the optical fiber at a desired position along the axial direction of the winding tube; and a tension control part for applying a desired tension to the optical fiber when winding the optical fiber on the winding tube.

[0021] The optical fiber winding device of the present invention further includes a tension measuring unit, which measures the tension applied to the optical fiber and feeds it back to the tension control unit so that the measured tension becomes the desired tension.

[0022] In the optical fiber winding device of the present invention, when the outer diameter of the optical fiber is D, the amount of movement Δ of the positioning part relative to the axial direction of the winding tube is D≤Δ<2D for each revolution of the winding tube.

[0023] The tension control unit of the optical fiber winding apparatus of the present invention applies a desired tension to the optical fiber when the third layer of the optical fiber is wound on the winding tube, which is stronger than the tension applied when the first and second layers of the optical fiber are wound on the winding tube.

[0024] The optical fiber winding apparatus of the present invention also includes an optical measuring device for optically measuring the optical fiber of the second layer.

[0025] This fiber optic testing method will be as follows: Figure 1 (c) shows the second layer of optical fiber 51-2 wound on the winding tube 12 on the take-up side as the test object. Furthermore, lateral pressure is applied to the second layer of optical fiber 51-2 by the third layer of optical fiber 51-3. This lateral pressure is adjusted by the tension when the third layer of optical fiber 51-3 is wound on the winding tube. That is, because lateral pressure is applied to the optical fiber of the test object from other optical fibers, the same lateral pressure and slight bending conditions as inside the optical cable can be reproduced.

[0026] Therefore, the present invention can provide an optical fiber testing method and an optical fiber winding device that can appropriately reproduce the same lateral pressure and minute bending conditions as those inside an optical cable during optical fiber testing.

[0027] In this optical fiber testing method, the optical fiber may be a single fiber, and the optical measurement may measure the interval of the optical fiber corresponding to the second layer; alternatively, the optical fiber may be three different fibers in each layer.

[0028] Furthermore, the above inventions can be combined where possible.

[0029] The present invention provides an optical fiber testing method and an optical fiber winding device that can appropriately reproduce the same lateral pressure and minute bending conditions as those inside an optical cable during optical fiber testing. Attached Figure Description

[0030] Figure 1This diagram illustrates a method of applying lateral pressure and slight bending to an optical fiber.

[0031] Figure 2 This is a diagram illustrating the structure of the optical fiber winding device of the present invention.

[0032] Figure 3 This is a diagram illustrating the structure of the optical fiber winding device of the present invention.

[0033] Figure 4 This is a diagram illustrating the positioning section of the optical fiber take-up device of the present invention.

[0034] Figure 5 This is a diagram illustrating the state of an optical fiber wound using the optical fiber winding device of the present invention.

[0035] Figure 6 This is a diagram illustrating the optical fiber testing method of the present invention. Detailed Implementation

[0036] Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to these embodiments. Furthermore, in this specification and the accompanying drawings, the same structural elements are indicated by the same reference numerals.

[0037] Figure 2 This is a diagram illustrating the structure of the optical fiber winding device according to this embodiment. The optical fiber winding device includes:

[0038] The take-up side winding tube 12 of the optical fiber 51 supplied from the feed-out side winding tube 11 is wound up.

[0039] A positioning part 13 for winding the optical fiber 51 to a desired position along the axial direction of the winding tube 12 on the take-up side; and

[0040] Tension control section 14 applies desired tension to optical fiber 51 when it is wound on the winding tube 12 on the take-up side.

[0041] An optical fiber 51 is pre-wound onto the delivery-side winding tube 11. Here, the optical fiber 50 is the test optical fiber, and the optical fiber 51 is used to create an environment similar to that inside the optical cable. The optical fiber 51 is delivered from the delivery-side winding tube 11 and wound onto the take-up-side winding tube 12. The power for winding is provided through the shaft portion of the take-up-side winding tube 12, for example, simply by using a motor.

[0042] The shaft of the feed-side winding tube 11 is designed to apply tension to the optical fiber. This function involves braking and motor operation. Tension can be applied to the optical fiber 51 by braking the rotation of the feed-side winding tube 11 or by using a motor to make the rotation speed of the feed-side winding tube 11 slightly slower than that of the take-up-side winding tube 12. The tension control unit 14 can control the tension applied to the optical fiber 51 by controlling the strength of the braking or the rotation speed of the motor.

[0043] like Figure 3 As shown, this optical fiber winding device also includes a tension measuring unit 15, which measures the tension applied to the optical fiber 51 and feeds it back to the tension control unit 14 so that the measured tension becomes the desired tension.

[0044] like Figure 3 As shown, the tension measuring unit 15 includes, for example, three pulleys (151, 152, 153) and a measuring device 150, arranged such that the optical fiber 51 travels in a curved path along the three pulleys. When tension is applied to the optical fiber 51, the force that causes the optical fiber 51 to tend towards a straight line applies an upward force to the central pulley 152. By measuring this force with the measuring device 150, the tension can be measured. Furthermore, by feeding this tension back to the tension control unit 14 through the tension measuring unit 15, the desired tension can be kept constant.

[0045] Figure 4 This diagram illustrates the structure of the positioning part 13. Each rotation of the take-up side winding tube 12 causes the positioning part 13 to move the optical fiber 51 along the axial direction of the take-up side winding tube 12, thereby ensuring that the optical fiber 51 is wound evenly without being concentrated in one place on the take-up side winding tube 12. For example, if the outer diameter of the optical fiber 51 is D, the amount of movement Δ of the positioning part 13 relative to the axial direction of the take-up side winding tube 12 per rotation is set as D ≤ Δ < 2D.

[0046] Let the outer diameter of optical fiber 51 be D. Let the axial movement of the positioning part 13 relative to the winding tube 12 of the winding side be Δ per revolution. By setting the movement Δ to D≤Δ, adjacent optical fibers in each layer can be prevented from contacting each other. Furthermore, by setting the movement Δ to Δ<2D, the optical fiber of the upper layer can be prevented from entering between the optical fibers of the lower layer.

[0047] Figure 5 This is a diagram illustrating the winding tube 12 with optical fiber wound around it. Figure 5 (A) is an overall view of the winding tube 12 on the take-up side. Figure 5 (B) is an enlarged cross-sectional view of part K. Figure 5 (B) Explanation and Figure 1 The same part of (c) and (Y).

[0048] First, the first layer of optical fiber 51-1 is wound onto the take-up side winding tube 12. Here, the tension used for winding the optical fiber 51-1 is only the minimum tension required to properly wind the optical fiber 51-1 onto the take-up side winding tube 12. For example, the tension can be set to 10-100 gf. Furthermore, when winding the second and third layers of optical fiber (51-2, 51-3) above the optical fiber 51-1, the tension can be higher than 10-100 gf to prevent the optical fiber 51-1 from breaking apart.

[0049] Next, the optical fiber 51-2 of the test object is wound around the second layer of the take-up side winding tube 12. Preferably, the tension used for winding the optical fiber 51-2 is as small as possible. This is because the lateral pressure applied to the optical fiber 51-2 can be controlled by the tension of the third layer of optical fiber 51-3. Therefore, the tension when winding the optical fiber 51-2 is set to the minimum tension required to properly wind the optical fiber to the extent that it reaches the take-up side winding tube 12. For example, this tension is 10 to 100 gf.

[0050] Alternatively, to confirm whether the tension when winding the optical fiber 51-2 is appropriate, a prescribed optical measurement can be performed on the optical fiber 51-2 before and after winding the second layer, so as to confirm that the characteristics of the optical fiber 51-2 have not changed.

[0051] Next, the third layer of optical fiber 51-3 is wound onto the take-up side winding tube 12 with a desired tension. This tension is used to apply a slight bend to the optical fiber 51-2, similar to the lateral pressure inside the high-density optical cable. Specifically, when the tension control unit 14 winds the third layer of optical fiber 51-3 onto the take-up side winding tube 12, it applies a desired tension to the optical fiber 51-3 that is stronger than the tension applied when the first and second layers of optical fiber (51-1, 51-2) are wound onto the take-up side winding tube 12.

[0052] This fiber optic winding device also includes an optical measuring instrument (not shown) for performing optical measurements on the second-layer fiber 51-2. The optical measuring instrument is, for example, an OTDR (Optical Time Domain Reflectometer). The optical measuring instrument is connected to the test object, i.e., the fiber 51-2, to perform the desired optical measurements (e.g., propagation loss measurement).

[0053] By making the optical fibers 51 of each layer the same type, the lateral pressure applied to the optical fibers inside the optical cable can be reproduced. Using this method, the same lateral pressure can be applied to the optical fiber 51-2 used for measurement as it is inside the optical cable.

[0054] Furthermore, in the above embodiment, it is described that the optical fibers (51-1, 51-2, 51-3) of each layer are three separate optical fibers, which are wound around the take-up side winding tube 12. In another embodiment, the optical fibers (51-1, 51-2, 51-3) of each layer can also be a single optical fiber. When measuring with an optical measuring instrument such as an OTDR capable of measuring the distribution along the length direction of the optical fiber, the three layers of optical fibers (51-1, 51-2, 51-3) can be treated as a single continuous optical fiber (i.e., the optical measuring instrument only measures the section of the second layer). In the case of the above embodiment, when winding the optical fiber 51 onto the take-up side winding tube 12, it is not necessary to cut the optical fiber or replace the feed-out side winding tube 11, which simplifies the optical fiber testing.

[0055] Figure 6 This is a diagram illustrating the optical fiber testing method of this embodiment. The optical fiber testing method is characterized by:

[0056] Three layers of optical fiber 51 are wound on the winding tube 12 on the winding side (step S01).

[0057] When winding the third layer of optical fiber 51-3 onto the take-up side winding tube 12, a desired tension is applied to the optical fiber 51-3 that is stronger than the tension applied when winding the first and second layers of optical fiber (51-1, 51-2) onto the take-up side winding tube 12; and

[0058] Optical measurements were performed on the second layer optical fiber 51-2 (step S02).

[0059] In this optical fiber testing method, optical fiber 51 can be a single fiber, and the optical measurement can measure the interval of optical fiber 51 corresponding to the second layer. Alternatively, optical fiber 51 can be three different fibers in each layer.

[0060] [Postscript]

[0061] The optical fiber testing method of this embodiment will be described below.

[0062] This embodiment describes a fiber optic testing method that applies lateral pressure to the optical fiber, and the method utilizes a testing apparatus.

[0063] The experimental apparatus is characterized by comprising:

[0064] The output-side winding tube used to deliver optical fiber;

[0065] A winding tube for winding optical fiber;

[0066] The delivery section of the delivery-side winding tube is fixed;

[0067] Secure the winding section of the winding tube on the winding side;

[0068] In order to provide rotational power to the winding tube for winding the optical fiber in the winding section;

[0069] A control mechanism that controls the rotation of the winding tube by braking or changing its speed when the optical fiber is delivered from the delivery section; and

[0070] A positioning part used to wind optical fiber in the desired position along the axial direction of the winding tube on the take-up side.

[0071] When winding the optical fiber pre-wound on the feed-side winding tube to the take-up-side winding tube, the control mechanism is used to maintain tension on the optical fiber during winding.

[0072] The optical fiber testing method is characterized by the following:

[0073] First, the first layer of optical fiber is pre-wound onto the winding tube on the take-up side.

[0074] Second, the optical fiber of the test object, which was pre-wound onto the feed-side winding tube, is wound onto the second layer of the take-up-side winding tube.

[0075] Third, the third layer of optical fiber is wound under tension onto the winding tube on the take-up side.

[0076] Fourth, optical measurements were performed on the optical fiber of the test object.

[0077] The test apparatus also includes a tension measuring unit applied to the optical fiber and a feedback unit that feeds back the measured tension to the control mechanism.

[0078] The feature is that, when the outer diameter of the optical fiber is D, the amount of movement Δ of the positioning part relative to the axial direction of the winding tube is D≤Δ<2D when the winding tube rotates once.

[0079] By employing this invention, lateral pressure and minute bending within high-density optical cables can be reproduced, and the micro-bending loss characteristics of the optical fiber can be tested to ensure that the loss characteristics of the optical cable are appropriate.

[0080] Explanation of reference numerals in the attached figures

[0081] 11: Send out the side winding tube

[0082] 12: Take-up side winding tube

[0083] 13: Positioning Department

[0084] 14: Tension Control Section

[0085] 15: Tension Measurement Section

[0086] 20: Metal Wire Mesh

[0087] 30: Sandpaper

[0088] 51: Fiber optic

[0089] 51-1: Fiber optic cable of layer 1

[0090] 51-2: Fiber optic cable in layer 2

[0091] 51-3: Fiber optic cable in layer 3

[0092] 150: Measuring instrument

[0093] 151-153: Pulleys

Claims

1. A fiber optic testing method, characterized in that, Three layers of optical fiber are wound around the winding tube; When winding the third layer of optical fiber onto the winding tube, apply a desired tension to the optical fiber that is stronger than the tension applied when winding the first and second layers of optical fiber onto the winding tube; as well as Optical measurements were performed on the optical fiber in the second layer.

2. The optical fiber testing method according to claim 1, characterized in that, The optical fiber is a single optical fiber, and In the optical measurement, the interval of the optical fiber corresponding to the second layer is measured.

3. The optical fiber testing method according to claim 1, characterized in that, The optical fiber consists of three different optical fibers in each layer.

4. An optical fiber take-up device, characterized in that... include: The winding tube that winds up the supplied optical fiber; A positioning part for winding the optical fiber to a desired position along the axial direction of the winding tube; as well as A tension control section that applies a desired tension to the optical fiber when it is wound onto the winding tube. The tension control unit applies a desired tension to the optical fiber when the third layer of the optical fiber is wound on the winding tube, which is stronger than the tension applied when the first and second layers of the optical fiber are wound on the winding tube.

5. The optical fiber winding device according to claim 4, characterized in that, It also includes a tension measuring unit, which measures the tension applied to the optical fiber and feeds it back to the tension control unit so that the measured tension becomes the desired tension.

6. The optical fiber winding device according to claim 4 or 5, characterized in that, When the outer diameter of the optical fiber is D, the amount of movement Δ of the positioning part relative to the axial direction of the winding tube for each revolution of the winding tube is D≤Δ<2D.

7. The optical fiber winding device according to claim 4, characterized in that, It also has an optical measuring device for optically measuring the optical fiber of the second layer.

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