JP2012018134A - Bend loss measuring device for optical fibers - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bend loss measuring device for optical fibers that can give warrant regarding a bend loss over the full length of any desired optical fiber.SOLUTION: A bend loss measuring device 1 for optical fibers comprising a feeding unit 51 to which a first bobbin 5 wound with an optical fiber F around is fitted and that feeds the optical fiber F from the first bobbin 5 and a take-up unit 81 to which a second bobbin 8 is fitted and that takes up around the second bobbin 8 the optical fiber F fed from the feeding unit 51 is further provided with a light source unit 3 that inputs light to one end F1 of the optical fiber F at the feeding unit 51 or the take-up unit 81, a light receiving unit 9 that measures the power of light outputted from the other end F2 of the optical fiber F at the feeding unit 51 or the take-up unit 81, a bend loss inflicting roller unit 7 that inflicts a bend loss on the optical fiber F after being fed from the feeding unit 51 and before being taken up by the take-up unit 81, and an arithmetic unit 13 that calculates the bend loss of the optical fiber F on the basis of the power of light measured by the light receiving unit 9.

Description

  The present invention relates to an optical fiber bending loss measuring apparatus.

  As a method for measuring the bending loss of an optical fiber, for example, a method standardized in Non-Patent Document 1 is known. In this document, an optical fiber is loosely wound around a mandrel having a diameter of 75 mm, and bending loss is measured. At this time, light having a wavelength of 1550 nm is used for measuring the bending loss of a single mode optical fiber, and light having a wavelength of 1300 nm is used for measuring the bending loss of a multimode optical fiber. ITU-T Recommendation G. In 657, bending loss at a plurality of wavelengths is defined.

IEC 60793-1-47, "Optical Fibers Part 1-47, Measurement methods and test procedures, Macrobending loss", July 2001, pp. 1-15

  Incidentally, in order to guarantee the quality of the entire length of the optical fiber, for example, 1 km to 1000 km, it is desired to measure the bending loss over the entire length of the optical fiber. However, in the conventional measurement method, since the optical fiber is wound around and fixed to a mandrel, the measurement is limited to the measurement of the bending loss of a local portion of the optical fiber, for example, several meters. Therefore, the conventional method cannot guarantee the bending loss over the entire length of the optical fiber.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an optical fiber bending loss measuring apparatus that can guarantee a bending loss over the entire length of a desired optical fiber.

  An optical fiber bending loss measuring apparatus according to the present invention is provided with a first bobbin around which an optical fiber is wound, and a payout unit that feeds the optical fiber from the first bobbin, and a second bobbin that is attached and fed out from the payout unit. The optical fiber is wound around the second bobbin, the light source unit that inputs light to one end of the optical fiber in the feeding unit or winding unit, and the other end of the optical fiber in the feeding unit or winding unit. Measured by a light receiving unit that measures the power of light, a bending loss applying roller unit that applies bending loss to the optical fiber after being fed out from the feeding unit and before being wound around the winding unit, and a light receiving unit. And an arithmetic unit for calculating the bending loss of the optical fiber based on the power of the light.

  In the optical fiber bending loss measuring apparatus according to the present invention, the bending loss according to the curvature of the bending loss applying roller portion is applied to the optical fiber after being drawn out from the feeding portion and before being taken up by the winding portion. Can be granted. Since the bending loss can be imparted by the bending loss imparting roller section while the optical fiber is moved in the winding process of the optical fiber, the bending loss can be imparted over a relatively long portion of the optical fiber. As an example, consider a case where the length from one end of the optical fiber to the other is, for example, 10 km. In this example, the length from the part of the optical fiber to which the bending loss is first imparted by the bending loss imparting roller section (hereinafter also referred to as the bending loss provision starting point) to the other end of the optical fiber is, for example, 0.005 km Suppose there is. Then, the bending loss can be imparted to the optical fiber while starting to impart the bending loss from the bending loss provision starting point and winding and moving the optical fiber. Therefore, the position where the bending loss is applied to the optical fiber moves in accordance with the movement of the optical fiber by winding. Here, the length from a part of the optical fiber to which the bending loss is finally given by the bending loss applying roller part (hereinafter also referred to as the bending loss applying end point) to one end of the optical fiber is, for example, 0.005 km. To do. In this case, a bending loss can be applied over a length of, for example, 9.99 km from the bending loss application start point to the bending loss application end point of the optical fiber. As described above, the bending loss can be measured over the entire length of the desired optical fiber (for example, 9.99 km), and the bending loss can be guaranteed over the entire length of the desired optical fiber.

  In the optical fiber bending loss measuring apparatus according to the present invention, the light source unit combines a plurality of light sources that output light of different wavelengths and the light output from the plurality of light sources and inputs the combined light to one end of the optical fiber. And a light receiving unit that receives the light output from the other end of the optical fiber into light of different wavelengths and the light demultiplexed by the branching filter. It is preferable to have a plurality of light receivers. In this case, the bending loss of the optical fiber can be measured at a plurality of wavelengths, and the wavelength dependence of the bending loss can be measured.

  In the optical fiber bending loss measuring apparatus according to the present invention, the wavelength line width of light input from the light source unit to one end of the optical fiber is 10 nm or more, and the light receiving unit receives light output from the other end of the optical fiber. It is preferable to have a demultiplexer that demultiplexes light of different wavelengths and a plurality of light receivers that respectively receive the light demultiplexed by the demultiplexer. In this case, it is possible to measure the bending loss of the optical fiber at a plurality of wavelengths without using a plurality of light sources as described above, and the wavelength dependence of the bending loss can be measured.

  In the optical fiber bending loss measuring apparatus according to the present invention, it is preferable that the bending loss applying roller portion rotates at a rotational speed corresponding to the winding speed of the optical fiber. In this case, the load applied to the optical fiber due to the bending loss applying roller portion can be suppressed.

  According to the present invention, it is possible to guarantee a bending loss over the entire length of a desired optical fiber.

FIG. 1 is a diagram showing a configuration of an optical fiber bending loss measuring apparatus according to the present embodiment. FIG. 2 is a diagram illustrating a configuration of Modification 1 of the light source unit and the light receiving unit. FIG. 3 is a diagram illustrating a configuration of Modification 2 of the light source unit and the light receiving unit.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

FIG. 1 is a diagram showing a configuration of an optical fiber bending loss measuring apparatus 1 according to the present embodiment. As shown in the figure, the optical fiber bending loss measuring apparatus 1 includes a light source unit 3, a feeding unit 51, pass line changing roller units 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ , a bending loss applying roller unit. 7, a winding unit 81, a light receiving unit 9, and a calculation unit 13.

  The light source unit 3 inputs light to one end F1 of the optical fiber F. The wavelength of light input from the light source unit 3 to the one end F1 of the optical fiber F is, for example, 1550 nm.

  The feeding portion 51 is a portion to which the bobbin (first bobbin) 5 around which the optical fiber F is wound is attached and the optical fiber F is fed from the bobbin 5. The feeding unit 51 includes a holder that holds the bobbin 5 and the rotary joint 11A. The bobbin 5 has a trunk portion around which the optical fiber F is wound and a pair of flange portions. The body of the bobbin 5 has a cylindrical shape made of metal or plastic. The outer diameter of the body portion of the bobbin 5 is a size that does not cause loss due to the bending of the optical fiber F at the bobbin 5, and is, for example, 30 mmφ. A pair of flange portions in the bobbin 5 are provided at both ends of the body portion to prevent the optical fiber F from being collapsed. The shaft of the holder that holds the bobbin 5 is inserted into the shaft hole of the body portion of the bobbin 5. The feeding speed of the optical fiber F may be adjusted by controlling the holder.

The pass line changing roller portions 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ are rotating bodies for changing the extending direction of the optical fiber F. The pass line changing rollers 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ are passively rotatable, and rotate while being dragged by the moving optical fiber F in the winding process. The pass line changing roller portions 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ have a body portion and a pair of flange portions. The body of the pass line changing roller section 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ has a cylindrical shape made of metal or plastic, and the outer diameter of this body section is for the optical fiber F to change the pass line. The size is such that loss due to bending at the roller portion does not occur, and is larger than, for example, 30 mmφ. The pair of flange portions provided at both ends of the body portion of the pass line changing roller portions 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ prevent the optical fiber F from slipping off. The number of pass line changing roller portions 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ is not particularly limited.

The extending direction of the optical fiber F is changed so as to bend along the trunk portions of the pass line changing roller portions 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ . The number of pass line changing roller units 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ is not particularly limited, but in the example shown in FIG. 1, four pass line changing roller units 6 ₁ , 6 ₂ , 6 ₃ , 6 are used. ₄ is provided. Of these, the two pass line changing roller portions 6 ₁ and 6 ₂ are extended from the feeding portion 51 and before the bending loss is imparted by the bending loss imparting roller portion 7. To change. The remaining two pass line changing roller portions 6 ₃ and 6 ₄ are the pass lines of the optical fiber F after being bent by the bending loss applying roller portion 7 and before being wound by the winding portion 81. To change. More specifically, the extending direction of the optical fiber F fed out from the feeding unit 51 upward, bends approximately 90 degrees pass line changing roller unit _61. The extending direction of the optical fiber F extending from the pass line changing roller unit ₆₁ is bent at approximately 90 degrees downward in the pass line changing roller unit 6 _2. Further, the extending direction of the optical fiber F extending from the bending loss causing roller unit 7, bends approximately 90 degrees pass line changing roller unit 6 _3. The extending direction of the optical fiber F extending from the pass line changing roller unit 6 ₃ bends to about 90 degrees below the path line changing roller unit 6 _4. The pass line changing roller portions 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ do not directly contribute to the bending loss measurement and can be omitted. However, by using the pass line changing roller portions 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ , the optical fiber F can be prevented from blurring and twisting.

The bending loss imparting roller section 7 is a rotating body that imparts bending to the optical fiber F after being fed out from the feeding section 51 and before being wound around the winding section 81. The bending loss imparting roller section 7 is rotatable and rotates at a peripheral speed corresponding to the linear speed of the optical fiber F that moves in the winding process. The bending loss applying roller portion 7 has a body portion and a pair of flange portions. The body portion of the bending loss applying roller portion 7 has a cylindrical shape made of metal or plastic. The outer diameter of the body part of the bending loss applying roller part 7 is smaller than the outer diameter of the body parts of the pass line changing roller parts 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ . The outer diameter of the body portion of the bending loss applying roller portion 7 is set according to the bending diameter of the optical fiber in the bending loss measurement as defined by, for example, ITU-T, and is, for example, 1 mm to 30 mmφ. The optical fiber F is bent so as to follow the body of the bending loss applying roller portion 7. Further, the pair of flange portions provided at both ends of the body portion of the bending loss applying roller portion 7 prevents the optical fiber F from being slipped off.

  The number of bending loss imparting roller portions 7 may be one or more, and the number is not particularly limited. In the example shown in FIG. 1, the number of bending loss applying roller portions 7 is nine. Depending on the measurement sensitivity of the light power in the light receiving unit 9, the bending loss (for example, 0.01 dB) by one bending loss applying roller unit 7 may not be measured. In such a case, it is possible to measure the bending loss by using a plurality of bending loss applying roller portions 7.

  The winding portion 81 is a portion to which an empty bobbin (second bobbin) 8 around which the optical fiber F is not wound is attached and the optical fiber F fed from the feeding portion 51 is wound around the bobbin 8. The winding unit 81 includes a holder that holds the bobbin 8 and a rotary joint 11B. The structure of the bobbin 8 is the same as that of the bobbin 5. A shaft of a winding drive mechanism that winds the optical fiber F is inserted into the shaft hole of the body portion of the bobbin 8. By adjusting the rotation speed of the bobbin 8 by controlling the winding drive mechanism, the winding linear velocity of the optical fiber F can be set to, for example, 500 m / sec.

  The light receiving unit 9 measures the power of light output from the other end F2 of the optical fiber F wound around the bobbin 8. A signal related to the power of light measured by the light receiving unit 9 is transmitted to the calculation unit 13.

  The rotary joints 11 </ b> A and 11 </ b> B reduce the load on the optical fiber caused by connecting the stationary optical fiber and the rotating optical fiber. Specifically, the rotary joint 11A connects the optical fiber Fa that extends from the light source unit 3 to the feeding unit 51 and is stationary, and one end F1 of the optical fiber F that is rotated by the rotation of the bobbin 5 at the connection unit S1. Connected. Further, the rotary joint 11B connects the optical fiber Fb that extends from the winding unit 81 to the light receiving unit 9 and is stationary, and the other end F2 of the optical fiber F that is rotated by the rotation of the bobbin 8 at the connection unit S2. Connected. In addition, the loss resulting from using the rotary joints 11A and 11B does not affect the measurement of the bending loss by suitably setting the rotational speeds of the connecting portions S1 and S2 of the rotary joints 11A and 11B.

  The computing unit 13 is a part that computes the bending loss of the optical fiber F based on the light power measured by the light receiving unit 9. The calculation unit 13 receives a signal related to the power of light transmitted from the light receiving unit 9. The calculation unit 13 includes a power P1 of light output from the other end F2 of the optical fiber F to which bending is not applied, and the other end F2 of the optical fiber F to which bending loss is applied by the bending loss applying roller unit 7. The bending loss L [dB] is calculated based on the power P2 of light output from.

Hereinafter, a supplementary description will be given of the procedure for measuring the bending loss of the optical fiber F using the optical fiber bending loss measuring apparatus 1 according to this embodiment. First, the shaft hole of the bobbin 5 around which the optical fiber F is wound is mounted on the shaft of the holder of the feeding portion 51. The shaft hole of the empty bobbin 8 on which the optical fiber F is not wound is mounted on the shaft of the holder of the winding unit 81. Next, the lower end (one end F1) of the optical fiber F wound around the bobbin 5 is connected and fixed to the optical fiber Fa at the connection portion S1 of the rotary joint 11A, and the optical fiber F wound around the bobbin 5 is fixed. The upper opening (the other end F2) is pulled out and is wound around the bobbin 8 via the pass line changing rollers 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ (without using the bending loss imparting roller section 7). The other end F2 of the optical fiber F is connected and fixed to the optical fiber Fb at the connection portion S2 of the rotary joint 11B. In this state, the power P1 of light output from the other end F2 of the optical fiber F is measured by the light receiving unit 9 (preparation stage 1). Subsequently, the bending loss applying roller portion 7 is brought into contact with a part of the optical fiber F extending from the feeding portion 51 to the winding portion 81 (preparation stage 2). Thereafter, the optical fiber F wound around the bobbin 5 is unwound and taken up by the take-up portion 81. Bending is applied to the optical fiber F moving in the winding process by the bending loss applying roller section 7 (bending loss applying stage). The light receiving unit 9 measures the power P2 of light output from the other end F2 of the optical fiber F to which bending is applied. Finally, the bending loss L [dB] of the optical fiber F is calculated by the calculation unit 13 based on the measured light power P1 and light power P2.

  Hereinafter, effects of the optical fiber bending loss measuring apparatus 1 according to the present embodiment will be described. Here, the case where the length from the one end F1 to the other end F2 of the optical fiber F is 10 km is considered as an example. In this case, in the above-described preparation stage 2, the length from the part of the optical fiber F that contacts the bending loss applying roller portion 7 (the bending loss applying start point) to the other end F2 of the optical fiber F is 0.005 km. And Then, in the above-described bending loss applying step, the moving optical fiber F after being fed by the feeding portion 51 and before being wound by the winding portion 81 is in accordance with the curvature of the bending loss applying roller portion 7. Bending can be imparted. Therefore, the position where bending is applied to the optical fiber F moves in accordance with the movement of the optical fiber F taken up. Here, in the state where one end F1 of the optical fiber F is fixed to the connection part S1 of the rotary joint 11A and the other end F2 of the optical fiber F is fixed to the connection part S2 of the rotary joint 11B, the optical fiber F It is assumed that the winding to the winding unit 81 is completed. In a state where the winding of the optical fiber F is completed, the length from the part of the optical fiber F that contacts the bending loss applying roller portion 7 (end of bending loss application) to one end F1 of the optical fiber F is 0.005 km. Suppose that In this case, bending can be applied over a length of 9.99 km from the bending loss application start point to the bending loss application end point in the optical fiber F. As described above, the bending loss can be measured over the entire length of the desired optical fiber (for example, 9.99 km), and the bending loss can be guaranteed over the entire length of the desired optical fiber. In the conventional method, the bending loss is measured in a state where the optical fiber is wound and fixed on the mandrel, so that only the local bending loss of the optical fiber can be measured. It cannot be guaranteed.

As mentioned above, although preferred embodiment was described in detail, this invention is not limited to the said embodiment. The outer diameter of the bending loss imparting roller portion 7 is smaller than the outer diameter of the pass line changing roller portions 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ , and the optical fiber bent by the bending loss imparting roller portion 7. A relatively high stress is likely to occur in F. For this reason, a load is applied to the optical fiber F. Therefore, the bending loss applying roller portion 7 is preferably rotated at a rotational speed corresponding to the winding speed of the optical fiber F, and the load on the optical fiber F can be suppressed. For example, the shaft of the rotational drive mechanism is inserted into the shaft hole of the bending loss applying roller portion 7 so that the bending loss applying roller portion 7 rotates at a rotational speed corresponding to the winding speed of the optical fiber F, The bending loss applying roller section 7 can be rotated by controlling the rotation driving mechanism.

  In the above description, the traveling direction of the light passing through the optical fiber F and the winding direction of the optical fiber F are the same. That is, in the above, light is input from the light source unit 3 to the one end F1 of the optical fiber F in a state where the optical fiber F fed out from the bobbin 5 of the feeding unit 51 is wound around the bobbin 8 of the winding unit 81. In addition, the configuration in which the light power output from the other end F2 of the optical fiber F is measured by the light receiving unit 9 (hereinafter also referred to as configuration A) is shown. However, the traveling direction of the light passing through the optical fiber F and the winding direction of the optical fiber F may be reversed. That is, in a state where the optical fiber F fed out from the bobbin 5 of the feeding unit 51 is wound around the bobbin 8 of the winding unit 81, light is input from the light source unit 3 to the other end F2 of the optical fiber F, A configuration in which the power of light output from one end F1 of the optical fiber F is measured by the light receiving unit 9 (hereinafter also referred to as configuration B) may be used.

Moreover, the light source part 3 and the light-receiving part 9 are not limited to what was shown to the said embodiment. FIG. 2 is a diagram showing a configuration of Modification 1 of the light source unit 3 and the light receiving unit 9 of the optical fiber bending loss measuring apparatus. As shown in the figure, the light source unit 3 preferably includes a plurality of light sources 31 and a multiplexer 32, and the light receiving unit 9 preferably includes a duplexer 91 and a plurality of light receivers 92. The plurality of light sources 31 output light having different wavelengths. In the case of the configuration A, the multiplexer 32 multiplexes the light output from the plurality of light sources 31 and inputs the light to one end F1 of the optical fiber F through the optical fiber Fa. The demultiplexer 91 demultiplexes light output from the other end F2 of the optical fiber F through the optical fiber Fa into light having different wavelengths. The plurality of light receivers 92 respectively receive the light demultiplexed by the demultiplexer. In the figure, the feeding portion 51, the pass line changing roller portions 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ , the bending loss applying roller portion 7, the winding portion 81, and the rotary joint 11 A shown in FIG. 11B are omitted. Alternatively, although not shown, in the case of the configuration B, the multiplexer 32 multiplexes the light output from the plurality of light sources 31 and inputs the light to the other end F2 of the optical fiber F through the optical fiber Fa. In addition, the demultiplexer 91 may demultiplex the light output from the one end F1 of the optical fiber F through the optical fiber Fa into light having different wavelengths. In any of the configurations A and B, the bending loss of the optical fiber F can be measured at a plurality of wavelengths, and the wavelength dependence of the bending loss can be measured.

FIG. 3 is a diagram illustrating a configuration of a second modification of the light source unit and the light receiving unit of the optical fiber bending loss measuring apparatus. The modification 2 is different from the modification 1 in the configuration of the light source unit 3. In the case of the above configuration A, it is preferable that the wavelength line width of light input from the light source unit 3 to the one end F1 of the optical fiber F via the optical fiber Fa is 10 nm or more. In this case, it is possible to measure the bending loss of the optical fiber F at a plurality of wavelengths without using a plurality of light sources 31 as in Modification 1, and the wavelength dependence of the bending loss can be measured. Furthermore, the wavelength line width of light input from the light source unit 3 to the one end F1 of the optical fiber F via the optical fiber Fa is more preferably 50 nm or more, and further preferably 100 nm or more. Also in this figure, the feeding portion 51, the pass line changing roller portions 6 ₁ , 6 ₂ , 6 ₃ , 6 ₄ , the bending loss applying roller portion 7, the winding portion 81, and the rotary joint shown in FIG. 11A and 11B are omitted. Or although not shown in figure, in the case of the said structure B, it is suitable that the wavelength line width of the light input into the other end F2 of the optical fiber F from the light source part 3 via the optical fiber Fa is 10 nm or more. is there. Even in this case, it is possible to measure the bending loss of the optical fiber F at a plurality of wavelengths without using the plurality of light sources 31 as in the first modification, and the wavelength dependence of the bending loss can be measured. Furthermore, the wavelength line width of light input from the light source unit 3 to the other end F2 of the optical fiber F via the optical fiber Fa is more preferably 50 nm or more, and further preferably 100 nm or more. .

  DESCRIPTION OF SYMBOLS 1 ... Optical fiber bending loss measuring apparatus, 3 ... Light source part, 51 ... Feed-out part, 6 ... Pass line change roller part, 7 ... Bending loss provision roller part, 81 ... Winding part, 9 ... Light receiving part, 11A , 11B ... Rotary joint, 13 ... Calculation unit, F ... Optical fiber, F1 ... One end, F2 ... Other end.

Claims (4)

A first bobbin around which an optical fiber is wound is attached, and a payout unit that pays out the optical fiber from the first bobbin;
A second bobbin is attached, and a winding unit that winds the optical fiber fed from the feeding unit around the second bobbin;
A light source unit for inputting light to one end of the optical fiber in the feeding unit or the winding unit;
A light receiving unit for measuring the power of light output from the other end of the optical fiber in the feeding unit or the winding unit;
A bending loss applying roller portion that applies bending loss to the optical fiber after being fed out from the feeding portion and before being wound around the winding portion;
A calculation unit that calculates the bending loss of the optical fiber based on the power of the light measured by the light receiving unit,
An optical fiber bending loss measuring apparatus. The light source unit includes a plurality of light sources that output light having different wavelengths, and a multiplexer that multiplexes light output from the plurality of light sources and inputs the light to the one end of the optical fiber,
The light receiving unit includes a duplexer that demultiplexes light output from the other end of the optical fiber into light having different wavelengths, and a plurality of light receivers that respectively receive the light demultiplexed by the duplexer. And having
The apparatus for measuring a bending loss of an optical fiber according to claim 1. The wavelength line width of light input from the light source unit to the one end of the optical fiber is 10 nm or more,
The light receiving unit includes a duplexer that demultiplexes light output from the other end of the optical fiber into light having different wavelengths, and a plurality of light receivers that respectively receive the light demultiplexed by the duplexer. And having
The apparatus for measuring a bending loss of an optical fiber according to claim 1.   The bending loss measurement of the optical fiber according to any one of claims 1 to 3, wherein the bending loss applying roller portion rotates at a rotation speed corresponding to a winding speed of the optical fiber. apparatus.

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