JP4089566B2 - Optical fiber recoat apparatus and optical fiber recoat method - Google Patents

Description

  The present invention relates to a technique for re-coating an optical fiber once the coating has been removed.

  An FBG (fiber Bragg grating) in which a diffraction grating is provided in an optical fiber can be manufactured by processing the length of the optical fiber. When processing the FBG, the coating covering the optical fiber core (also referred to as a strand or core) is partially removed (removed) from the optical fiber, and the exposed optical fiber core is irradiated with laser light. By forming (writing) a diffraction grating, the optical fiber core portion is processed into an FBG, and then the coating is recoated (recoated) on the FBG portion.

  Examples of the coating material for recoating include polyimide and UV curable resin.

  As a conventional technique for recoating polyimide on FBG, there is a dip method. The dip method uses a mold having a thin groove on a metal plate. FBG is put into a groove on the mold, a polyimide precursor is injected around the FBG, the groove is covered and the mold is heated, so that the polyimide precursor is transformed into polyimide and the FBG is recoated.

  There are VYTRAN products (described in Non-Patent Document 1) and Patent Document 1 as general-purpose recoating devices for general optical fibers. The device of Non-Patent Document 1 is similar to that described in Paragraphs 0005 to 0006 of Patent Document 1. As shown in FIG. 4, each of these apparatuses places an optical fiber on a die (die) 101 provided with a groove 103 that matches the outer diameter of the optical fiber so that the longitudinal direction of the optical fiber is in a horizontal plane. Then, a die having a covering material filling portion 102 having a groove width and groove depth increased from above is overlaid, and the covering material filling portion 102 is filled with a covering material made of a UV curable resin, and the covering material is solidified by ultraviolet irradiation. To do. In the apparatus of Non-Patent Document 1, the recoat part is non-uniform. Therefore, in Patent Document 1, when both ends of the optical fiber are held by clamps and the optical fiber is rotated about the center of the diameter of the optical fiber, it is not rotated. Patent Document 1 discloses that a uniform recoat portion is obtained as compared with the above.

  Further, there is a device disclosed in Patent Document 2 as an apparatus for recoating an optical fiber in which a diffraction grating is written. This apparatus includes a mechanism for applying an appropriate constant tension during a recoating operation, a mechanism for moving an extruder equipped with a split die in the longitudinal direction of the optical fiber, and the like.

JP 2002-365497 A JP 2001-013334 A URL http: // www. vytran. com / ptr2 00. html As of June 18, 2003

  In the dip method, since the dimension of the recoat portion is determined by the groove provided in the mold, the length and thickness of the recoat portion cannot be arbitrarily changed. Further, in the dip method, since the optical fiber is horizontally placed and recoated, the thickness of the upper and lower coatings of the optical fiber is not uniform due to the influence of gravity.

  In the method of Patent Document 1, since the optical fiber is placed horizontally, the coating material is biased downward due to gravity, and it is difficult to apply uniformly over the entire circumferential direction of the optical fiber. In addition, it is necessary to cure the coating material by irradiating ultraviolet rays with a UV lamp after coating, but a metal die does not transmit ultraviolet rays, and the die must be made of a material that can transmit ultraviolet rays. Quartz is an example of a material that can transmit ultraviolet rays. However, quartz is difficult to process and is easily damaged. If there are scratches on the die, unevenness will occur on the recoat part. There is a possibility that the strength of the optical fiber is deteriorated by the scratch. Further, in the method of Patent Document 1, since the coating material thickness is determined by the width and depth of the groove of the die, it is difficult to process the groove and it is difficult to reduce the coating material thickness. Only one groove corresponding to one type of coating material thickness can be produced.

  In order to recoat the optical fiber in which the diffraction grating is written, it is necessary to add a management function of the optical fiber tension to the devices of Patent Document 1 and Non-Patent Document 1 that are intended for general optical fibers. The devices of Patent Document 1 and Non-Patent Document 1 do not have an optical fiber tension management function, and thus may cause irreparable damage to the diffraction grating or the optical fiber during recoating.

  Further, as in Patent Document 1, if the optical fiber is rotated about the diameter center of the optical fiber as an axis, the optical fiber may be damaged by twisting. In addition, when a coating material is coated on a rotating optical fiber, a frictional force is generated between the filled coating material and the coating material coated on the optical fiber, so that fixing and rotation of the clamp portion is ideal. Even if it is true, a twisting force is applied to the optical fiber, which may damage the optical fiber.

  Therefore, the devices of Patent Document 1 and Non-Patent Document 1 are not suitable for recoating the optical fiber core wire on which the diffraction grating is written.

  In FIG. 6 of Patent Document 2 which is an apparatus for recoating an optical fiber in which a diffraction grating is written, the optical fiber to be recoated is fixed, and the die for recoating moves from bottom to top in the longitudinal direction of the optical fiber. . While the die is moving at a constant speed (acceleration 0), the resin in the die is not subjected to motion acceleration, and stable recoating can be performed. However, when the die starts and stops, Since acceleration occurs, a force acts on the resin, making it difficult to perform uniform recoating.

  In addition, Patent Document 2 does not provide a detailed description of a method for fixing an optical fiber to be recoated, and only mentions keeping the tension constant and using a fixing member. The method, the specific shape of the fixing member, and the fixing method of the optical fiber are not disclosed.

  Therefore, an object of the present invention is to provide an optical fiber recoating apparatus and an optical fiber recoating method that can solve the above-described problems and perform more uniform recoating.

To achieve the above object, the apparatus of the present invention applies a coating material to the exposed optical fiber core of the optical fiber in which the coating is partially removed and a diffraction grating is formed on the exposed optical fiber core. In the optical fiber recoating apparatus for applying the coating , the optical fiber core wire is formed by fixing the coating material that has a hole through which the optical fiber core wire passes vertically and is fixed horizontally and injected around the hole. and a die applied to the, an arm passed pointed bypassing the dice from above the die to below in order to hold the optical fiber above and below the die, moving means for moving the arm up and down comprising a said die consists half die break up into two about said hole, it from the aforementioned arms, a horizontal arm extending horizontally from both ends of the vertical arm and該鉛straight arm portion , In which a pulley to turn multiplied by the optical fiber to the distal end of the horizontal arm portion.

  The moving means may include a ball screw that is screwed into a female screw provided on the arm and extends vertically, and a stepping motor that rotates the ball screw.

You may provide the image pickup means which faced the said hole from under the said die, and the image display means which expands and displays the image when the said optical fiber core wire is inserted | pinched in this hole.

  You may provide the air slide table which moves the said imaging means to the position at the time of use which left | separated the vicinity of the said die from the position at the time of use which faced the hole of the said die.

  An XY stage that moves the dice in two horizontal directions may be provided.

  You may provide the memory | storage means to memorize | store the up-down movement start position and up-down movement end position of the said arm.

  You may provide the weight attached to the said optical fiber and applying a tension | tensile_strength to the said optical fiber.

  The coating material may be an ultraviolet curable resin, and a UV lamp may be provided that irradiates the optical fiber core wire with the coating material that has passed through the hole of the die from two horizontal directions.

  The coating material may be an ultraviolet curable resin, and the optical fiber core wire with the coating material that has passed through the hole of the die may be irradiated with ultraviolet rays obliquely from below.

  The coating material may be an ultraviolet curable resin, and may include an irradiation control unit that irradiates ultraviolet rays during a period from the start of vertical movement of the arm to the end of vertical movement.

The coating material may be polyimide, and a heating unit that heats the optical fiber core wire with the coating material that has passed through the hole of the die may be provided.

The heating means may be a half heating means in which a hole through which an optical fiber cored wire with a coating material passes is divided into two horizontally.

Hole of the die may be reversed conical have large upward opening diameter than the downward opening diameter.

The covering material may be stored in the upward opening of the die hole, and the optical fiber cored wire with the covering material may be taken out from the downward opening by moving the optical fiber core from above to below.

  Control means for controlling the moving speed of the arm to an arbitrary set speed may be provided.

  Control means for controlling the number of movements of the arm to an arbitrarily set number of times may be provided.

The method of the present invention carried out using the apparatus by injecting coating material to the upper Symbol the upward opening of the hole of the die, by moving from top to bottom the optical fiber, to the optical fiber The coating material is applied, the optical fiber coated with the coating material is taken out from the downward opening of the die , and then dried and cured to coat the optical fiber .

  Before injecting the covering material into the die, the vertical movement start position and vertical movement end position of the arm are stored in the storage means in advance, and the arm is aligned with the vertical movement start position read from the storage means. Thereafter, a coating material may be injected into the die, and the arm may be moved to a vertical movement end position.

  The coating thickness may be adjusted by controlling the movement speed and the number of movements of the arm based on the hole diameter of the die.

  The thickness of the coating may be targeted to the same level as the thickness of the coating before removal.

  The die and the optical fiber core may be aligned with each other based on the image displayed on the image display means.

  The present invention exhibits the following excellent effects.

  (1) Since the die does not move, the coating material is not accelerated and stable recoating can be performed.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  As shown in FIG. 1, an optical fiber recoat apparatus according to the present invention has a hole through which an optical fiber core wire, which is a part of an optical fiber 1, passes vertically, and is fixed horizontally and covers the periphery of the hole. A die 2 capable of injecting a material (not shown), and an arm 3 passed around the die 2 from above to below the die 2 to hold the optical fiber 1 above and below the die 2; By providing the optical fiber carrier 4 for moving the optical fiber up and down by moving the arm 3 up and down, the optical fiber core is passed from the top to the bottom of the die 2 into which the coating material has been injected. A coating material is applied around the optical fiber core wire. An XY stage 5 that holds the die 2 and moves in two horizontal directions, an air slide table 7 that holds and moves the CCD camera 6 as an imaging means for imaging the die 2, and the optical fiber transport unit 4 include: It is installed on a horizontal surface plate 8.

  The arm 3 is vertically projected from the vertical arm 11, the upper horizontal arm 12 and the lower horizontal arm 13 extending horizontally from the upper and lower ends of the vertical arm 11, and the vertical arm 11. The female screw portion 14 is integrally formed and has a substantially U shape as a whole. Although not shown, the female screw portion 14 has a female screw penetrating in the vertical direction. An upper pulley 15 and a lower pulley 16 are provided at the distal end of the upper horizontal arm portion 12 and the distal end of the lower horizontal arm portion 13, respectively. The upper pulley 15 and the lower pulley 16 guide the optical fiber 1 that has been wound vertically, and change the extending direction of the optical fiber 1 horizontally. Since the upper pulley 15 and the lower pulley 16 are positioned so that their rotational axes overlap each other and the pulley diameters are equal to each other, the optical fiber 1 stretched between the upper pulley 15 and the lower pulley 16 is made vertical. be able to.

  An upper clamp 17 and a lower clamp 18 for fixing and releasing the optical fiber 1 are provided on the horizontal portion of the upper horizontal arm portion 12 and the horizontal portion of the lower horizontal arm portion 13, respectively. A guide pin 19 for guiding the optical fiber 1 downward is provided at the base end of the upper horizontal arm portion 12, and a weight (not shown) can be attached to the optical fiber 1 guided downward. .

  The moving means for moving the arm 2 up and down includes a ball screw 21 that is screwed into the female screw of the female screw portion 14 and extends vertically, and a stepping motor 22 that rotates the ball screw 21.

  In the optical fiber transport unit 4, when the stepping motor 22 is rotated in one direction, the entire arm 2 holding the optical fiber 1 moves upward, and when the stepping motor 22 is rotated in the reverse direction, the arm holding the optical fiber 1 is moved. 2 will move down.

  As shown in FIGS. 2 (a) to 2 (c), the die 2 is formed by forming a hole 32 in the square plate 31, but here, the half hole is formed so that the hole 32 is divided into two from the center. This is a half die that uses square plate pieces 31a and 31b formed with 32a and 32b together. When the half die is used, the optical fiber core wire 1a is inserted into the hole 32 by sandwiching the optical fiber core wire 1a in the half holes 32a and 32b. The square plate pieces 31a and 31b constituting the die 2 are fixed to the die attachment arms 33a and 33b shown in FIG. 1 by screws or the like. The die attachment arms 33 a and 33 b are mounted on the XY stage 5. Since the XY stage 5 can be accurately moved in two horizontal directions by the X-axis stepping motor 34 and the Y-axis stepping motor 35, the horizontal position between the hole 32 and the optical fiber 1 held in the arm 2. Matching can be performed precisely.

  The hole 32 of the die 2 is formed so that the upward opening diameter is larger than the downward opening diameter. In the example of FIG. 2, the hole 32 has an inverted truncated cone shape. The covering material can be injected and stored in the upward opening. Although omitted in FIG. 1, as shown in FIG. 2B, an injection means 36 protruding from the oblique direction is provided on the hole 32, and a liquid / fluid coating material 37 is injected into the hole 32. be able to. The injecting means 36 may be constituted by a tube so as to discharge the covering material, or may be formed in a needle shape and dropped along the covering material.

  When the quartz optical fiber is coated, the diameter of the hole of the die 2 (downward opening diameter) is 1.02 to 1.04 times the diameter of the optical fiber when the re-coating is completed when the coating material is an ultraviolet curable resin. In the case where the coating material is a polyimide precursor, it is preferably 1.37 to 1.39 times the diameter of the optical fiber when re-coating is completed.

  As shown in FIG. 1, two CCD cameras 6 as imaging means are provided and face the dice 2 from different angles below the dice 2. The air slide table 7 can move these CCD cameras 6 from the illustrated use position to a non-use position (not shown) that is separated from the vicinity of the die 2.

  When the coating material is an ultraviolet curable resin, a UV lamp 41 for irradiating the optical fiber cored wire 1 a with the coating material that has passed through the hole of the die 2 from two horizontal directions is installed under the die 2. The UV lamp 41 may irradiate ultraviolet rays obliquely from below. When the coating material is polyimide, heating means (not shown) is installed under the die 2 in place of the UV lamp 41. The heating means is preferably a halved heating means in which a hole through which an optical fiber cored wire with a coating material passes is divided into two horizontally.

  The operation panel 42 is provided with switches and instruments for controlling and operating each part of the optical fiber recoat apparatus, and a computer is accommodated therein. Storage means for storing the vertical movement start position and vertical movement end position of the arm 3 by the operation panel 42, control means for controlling the movement speed of the arm 3 to an arbitrary set speed, and the number of movements of the arm 3 as an arbitrary set number of times The control means for controlling, the period from the start of the vertical movement of the arm 2 to the end of the vertical movement, the irradiation control means for irradiating ultraviolet rays, the means for setting the heating temperature and the heating time, etc. are realized.

Although not shown, the optical fiber recoat apparatus is provided with image display means for enlarging and displaying an image taken by the CCD camera 6 when the optical fiber core wire 1a is sandwiched in the hole 32 of the die 2.

  Hereinafter, the re-coating process performed by the optical fiber recoat apparatus of FIG. 1 will be described.

  The optical fiber 1 to be recoated is obtained by removing the coating at a part in the longitudinal direction of the optical fiber 1 and processing the exposed optical fiber 1a into, for example, FBG.

  First, the optical fiber 1 to be recoated is hung around the upper pulley 15 and the lower pulley 16 of the arm 3 so that the optical fiber 1 is hung between the upper pulley 15 and the lower pulley 16. 17 and the lower clamp 18. At the time of fixing, a weight is suspended from the optical fiber 1 below the guide pin 19 in a state where the optical fiber 1 is not fixed by the upper clamp 17 so that the tension of the optical fiber 1 becomes a desired magnitude. Since the optical fiber 1 is fixed in the lower clamp 18, a tension corresponding to the weight of the weight is applied to the optical fiber 1 extending downward from the guide pin 19 through the lower pulley 16 and the upper pulley 15 from the lower clamp 18. . A desired tension can be applied by adjusting the weight of the weight. Thereafter, when the optical fiber 1 is fixed by the upper clamp 17, the tension of the optical fiber 1 between the upper pulley 15 and the lower pulley 16 is fixed to a desired magnitude.

  Next, the optical fiber 1 is passed through the hole 32 of the die 2 so as to be sandwiched between the square plate pieces 31a and 31b. At this time, an image obtained by photographing the hole 32 of the die 2 from two obliquely lower angles at the use position shown by the CCD camera 6 on the air slide table 7 is enlarged and displayed on the image display means. The die 2 can be aligned while viewing this image.

  The alignment of the die 2 is performed by moving the XY stage 5 in two horizontal directions by an X-axis stepping motor 34 and a Y-axis stepping motor 35. It should be noted that the operation panel 42 can be operated by switching between a coarse adjustment mode for roughly aligning and a fine adjustment mode for finely aligning.

  The image display means displays an image of the optical fiber 1 protruding from the downward opening of the hole 32 of the die 2. From this image, it can be visually confirmed whether or not the optical fiber 1 passes through the center of the opening. Note that the image of the die 2 is taken from below because it is easy to focus on the lower surface of the mating surface of the square plate pieces 31a and 31b of the die 2, easy to illuminate the camera (not shown), and the penetration of the covering material (light There is a reason that a covering material that appears in the gap between the fiber core wire 1a and the hole 32 is seen. If an image is taken from above, it is difficult to focus on the lower surface of the mating surface, and the penetration of the covering material is not seen.

  When the optical fiber 1 does not pass through the center of the opening, the XY stage 5 is finely adjusted to eliminate the deviation. At this time, since the two CCD cameras 6 are picking up images from 90 ° different angles, it is possible to observe the deviation in both directions of the XY axes.

  When the alignment is completed and the optical fiber 1 passes through the center of the opening, the air slide table 7 may be moved to move the CCD camera 6 to the non-use position. The non-use position is a position that does not interfere with other members in the recoating process to be performed.

  In the recoat process, first, the vertical movement start position and the vertical movement end position of the arm 3 are set. The recoat length can be determined by this setting. When the arm 3 is moved to the vertical movement start position by the optical fiber transport unit 4, that is, the position of the arm 3 indicated by the solid line in FIG. 1, the lower end of the optical fiber 1 (optical fiber core wire 1 a) to be recoated is the die 2. Will be located around the downward opening of the hole 32.

  Next, as shown in FIG. 2B, the coating material 37 is injected into the hole 32 from the injection means 36. When the covering material 37 oozes out under the hole 32, the movement of the arm 3 is started by the optical fiber transport unit 4. When the arm 3 moves down, the optical fiber 1 also moves down, so that the optical fiber core wire 1a comes out below the hole 32. At that time, the coating material stored in the hole 32 is attached to and applied to the optical fiber core wire 1a. Since the optical fiber core wire 1a passes through the center of the hole, the coating material is uniformly applied around the optical fiber core wire 1a. The recoat thickness (the thickness of the covering material) at this time is determined by the diameter of the hole 32. FIG. 2C shows a state in which the coating material 51 is attached and applied to the optical fiber core wire 1 a that has come out under the hole 32.

  The recoat thickness can also be changed by the moving speed of the optical fiber 1. The moving speed of the optical fiber 1 can be arbitrarily controlled on the operation panel 42. Further, by repeatedly applying the recoating process to the same portion of the optical fiber 1, the recoat thickness can be changed by stacking and attaching the coating material.

  When the coating material is an ultraviolet curable resin, the ultraviolet curable resin is irradiated with ultraviolet rays from the UV lamp 41 to the optical fiber cored wire 1a with the ultraviolet curable resin that has passed through the hole of the die 2 so that the ultraviolet curable resin is primarily solidified. When the coating material is polyimide, heat is applied to the optical fiber cored wire 1a with the polyimide precursor that has passed through the hole of the die 2 by a heating means to primaryly solidify the polyimide precursor. However, the movement of the optical fiber 1 is not started until the heating means reaches a predetermined temperature.

  In the above re-coating process, in the present invention, since the die 2 is fixed and the optical fiber 1 is moved up and down, inertia force does not act on the covering material at the start and end of the movement. Therefore, the non-uniform recoat thickness at the start and end of movement that occurs in the prior art for moving the die 2 does not occur in the present invention.

  Further, in the present invention, the image of the CCD camera 6 is enlarged and displayed, and the dies 2 and the optical fiber core 1a are precisely aligned with the XY stage 5 while viewing the image, so that the recoat thickness is uniform. Become.

  Next, an example in which polyimide re-coating is performed will be described.

  The polyimide coating is removed using hydrazine as a solvent for a part of the optical fiber having a polyimide coating in the longitudinal direction, FBG is written on the optical fiber core, and then the FBG is recoated with polyimide.

  The die 2 has a hole penetrating in the center of a metal flat plate, cuts a truncated cone-shaped groove aligned with the center of the hole, and divides the flat plate in half so that the truncated cone-shaped groove is halved from the center. To.

  In the optical fiber recoat apparatus of FIG. 1, the optical fiber 1 in which FBG is written on the optical fiber core wire 1a is set in the vertical direction. At that time, the lower side of the optical fiber 1 is fixed to the arm 3 by the lower clamp 18, and the upper side of the optical fiber 1 is hung around the upper pulley 15 and the guide pin 19 to attach a weight. If the tension applied to the optical fiber 1 by the weight is too small, the slack of the optical fiber is caught on the die 2 when the optical fiber 1 moves, and re-coating cannot be performed with a uniform thickness. On the other hand, if the tension is too large, re-coating is performed with the FBG being distorted. For this reason, 5-50 g is appropriate for the weight of the weight.

  The die 2 is set so that the optical fiber 1 is sandwiched by the central through hole. At that time, the center of the optical fiber 1 and the hole 32 is accurately aligned while viewing the image of the image display means by imaging the through hole for setting the optical fiber 1 obliquely from the lower right and the lower left by the CCD camera 6. Can do.

  Next, the arm 3 is moved so that the position of the die 2 coincides with the position where re-coating starts, and the height of the optical fiber 1 is adjusted. The vertical movement of the arm 3 can be electronically controlled by the operation panel 42, and the recoating start position can be stored as the vertical movement start position. Similarly, the arm 3 is moved so that the position of the die 2 coincides with the position where the re-coating ends, the height of the optical fiber 1 is adjusted, and the re-coating end position is stored as the vertical movement end position. Thus, the recoat length can be freely changed by storing the position of the optical fiber 1 at the start and end of re-coating.

  Next, the position of the optical fiber 1 (the optical fiber core wire 1a on which FBG is written) is aligned with the previously stored recoating start position, and the polyimide precursor is placed in the opening of the hole 32 of the die 2 by the injection means 36. Inject. From this state, the position of the optical fiber 1 is moved downward. By moving to the re-coating end position, the polyimide precursor is applied to the optical fiber core wire 1a.

  At the same time as the application of the polyimide precursor is completed (that is, immediately below the hole 32 of the die 2), the heating means heats the polyimide precursor applied to the optical fiber core wire 1a, so that the polyimide precursor is dried and solidified. The heating means is located on the left and right of the optical fiber 1 and is set to heat the optical fiber core wire 1a to 300 ° C. Heating by the heating means is performed for several seconds.

  Then, the polyimide precursor is transformed into polyimide by heating the optical fiber core wire 1a obtained by drying and solidifying the applied polyimide precursor in a furnace at 300 ° C. for several minutes.

  If the hole diameter of the die 2 is too large, the coating thickness of the polyimide precursor becomes non-uniform, so 110% to 120% of the diameter of the optical fiber core wire is appropriate.

  Moreover, the application | coating thickness of a polyimide precursor can be changed by changing the moving speed of an optical fiber. If the target coating thickness cannot be obtained by one recoating process (moving the optical fiber downward once), the target coating thickness can be obtained by repeating the recoating process several times.

  FIG. 3 shows a side cross-section of an optical fiber 1 that has been recoated according to the present invention. That is, the coating 52 is applied to the optical fiber core wire 1a from which the coating is removed from the optical fiber 1 having the coating. The recoat thickness t is set to about 10 μm, which is the thickness of the coating before removal, so that bending and distortion of the optical fiber 1 do not become uneven. The wrap length l over which the new coating 52 overlaps the original coating is preferably small, but is suitably about 30 mm so that the coating 52 does not peel off.

  In the alignment procedure shown in FIG. 2, the recoat thickness can be reduced to about 3 μm by setting the hole diameter of the die 2 to 200 μm and the moving speed of the optical fiber 1 to 91.3 m / sec. The target recoat thickness of 10 μm can be achieved by performing the recoat process three times under conditions.

  By changing the hole diameter of the die 2, it is possible to cope with the re-covering of the small-diameter optical fiber. In the re-coating of the small-diameter optical fiber, when the hole diameter of the die 2 is about 80 μm, the polyimide precursor can be applied to the optical fiber core 1a with a uniform thickness. In the present invention, since the die 2 is fixed and the optical fiber 1 is moved downward, the polyimide precursor stored in the die 2 is not affected by gravity (acceleration), and the optical fiber 1 is not rotated. The bending or distortion of the optical fiber 1 does not become uneven, and re-coating can be performed satisfactorily.

  Next, an example in which UV-curing resin re-coating is performed will be described.

  A polyimide coating is removed with a mixed solution of ethylenediamine and hydrazine to a part of the longitudinal direction of an optical fiber having a polyimide coating, FBG is written on the optical fiber core, and then this FBG is recoated with an ultraviolet curable resin. And

  In the optical fiber recoat apparatus of FIG. 1, the optical fiber 1 in which FBG is written on the optical fiber core wire 1a is set in the vertical direction. At that time, the upper side of the optical fiber 1 is fixed to the arm 3 by the upper clamp 17 and a tension is applied by attaching a weight to the lower side of the optical fiber 1 to remove the slack of the optical fiber 1. The dice 2 divided into two are brought close to the optical fiber 1 by the movement of the XY stage 5, the dice 2 are closed, and the optical fiber 1 is passed through the central hole 32. Here, the image of the CCD camera 6 is enlarged and displayed so that the optical fiber 1 and the edge of the hole 32 do not contact each other, and the XY stage 5 is finely adjusted by viewing the image. The recoating start position is set to the optical fiber 1 with the coating remaining so that the die 2 does not touch the optical fiber core 1a. Further, when the dice 2 are closed, the optical fiber 1 is not caught.

  In order to make the thickness of the UV curable resin to be applied an outer diameter of the UV curable resin so as to be 1.1 to 1.3 times the diameter of the optical fiber core wire 1a, the hole diameter of the die 2 is set to The diameter is 1.16 times to 1.24 times the diameter of the optical fiber core wire 1a. For example, when the optical fiber core wire 1a is a quartz optical fiber having a diameter of 125 μm, the hole diameter of the die 2 is set to 145 μm to 155 μm. The reason why the thickness of the UV curable resin is set to 1.1 to 1.3 times the diameter of the optical fiber core wire 1a at the coating outer diameter is that the UV curable resin swells due to humidity and applies strain to the optical fiber 1. This is because the thickness can prevent this.

  After the alignment of the die 2, the re-coating start position and the re-coating end position of the arm 3 are set. At this time, the length of the ultraviolet curable resin to be coated on the polyimide coating is preferably 1 mm to 5 mm.

  Thereafter, an ultraviolet curable resin is injected into the die 2. In addition, in order to make a viscosity low when apply | coating an ultraviolet curable resin, it is good to preheat an ultraviolet curable resin to 45 to 55 degreeC.

  When the position of the optical fiber 1 is moved downward from this state, an ultraviolet curable resin is applied to the optical fiber 1. Immediately below the hole 32 of the die 2, ultraviolet rays are irradiated from the UV lamp 41 to cure the ultraviolet curable resin.

  Here, by adjusting the moving speed of the optical fiber 1, the ultraviolet curable resin can be applied to an arbitrary thickness. Further, the moving distance of the optical fiber 1 can be controlled by giving a target position to the stepping motor 22 of the optical fiber transport unit 4 and can be an arbitrary recoat length.

It is a block diagram of the optical fiber recoat apparatus which shows one Embodiment of this invention. It is a perspective view of a die, (a) shows a mode that a dice is divided and an optical fiber is pinched in a hole, (b) shows a mode that a covering material is poured into a hole, and (c) shows an optical fiber below. The state of moving is shown. It is a sectional side view of a recoated optical fiber. It is a perspective view of the die | dye used for the conventional optical fiber recoat apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical fiber 1a Optical fiber core wire 2 Dies 3 Arm 4 Optical fiber conveyance part 5 XY stage 6 CCD camera 7 Air slide table 15 Upper pulley 16 Lower pulley 21 Ball screw 22 Stepping motor 32 Hole

Claims (19)

In an optical fiber recoat apparatus for coating the exposed optical fiber core of the optical fiber in which the coating is partially removed and a diffraction grating is formed on the exposed optical fiber core to apply the coating ,
A die that has a hole through which the optical fiber core passes vertically and is fixed horizontally and is applied to the periphery of the hole, and a die that coats the optical fiber core , and above and below the die. comprising an arm passed pointed bypassing the dice from above the die to the lower holding a optical fiber, and a moving means for moving the arm up and down,
The die comprises a half die that is divided into two parts around the hole, and the arm comprises a vertical arm part and a horizontal arm part extending horizontally from both ends of the vertical arm part. An optical fiber recoating apparatus, wherein a pulley for wrapping the optical fiber is provided at a tip . It said moving means includes a ball screw extending vertically screwed into the female screw provided in the arm, an optical fiber recoating device according to claim 1, characterized in that comprising a stepping motor for rotating the ball screw. An imaging means to face the said hole from the bottom of the die, the light according to claim 1, comprising the image display means to enlarge the image when sandwiching the optical fiber in the hole Fiber recoat equipment. 4. An optical fiber recoat apparatus according to claim 3, further comprising an air slide table for moving the imaging means from a use position facing the hole of the die to a non-use position away from the vicinity of the die. . Optical fiber recoat device according to claim 1, comprising the XY stage for moving the die in the two horizontal directions. Optical fiber recoat device according to claim 1, further comprising a storage means for storing upper and lower movement end position with the vertical movement start position of the arm. Optical fiber recoat device according to claim 1, further comprising a weight for applying a tension to the optical fiber attached to the optical fiber. The said coating | covering material is an ultraviolet curing resin, Comprising: The optical fiber core wire with the coating | coated material which passed the hole of the said die was equipped with the UV lamp which irradiates an ultraviolet-ray from two horizontal directions or diagonally downward. 1. An optical fiber recoat apparatus according to 1. The coating material is a polyimide, an optical fiber recoating device according to claim 1, further comprising a heating means for heating the optical fiber core with a coating material which has passed through the hole of the die. 10. The optical fiber recoating apparatus according to claim 9 , wherein the heating means is a half heating means in which a hole for passing an optical fiber cored wire with a covering material is divided into two horizontally. Hole of the die, optical fiber recoat device according to claim 1, wherein the compared in a downward opening diameter is upward opening diameter is large inverted cone shape. The covering material is stored in the upward opening of the die hole, and the optical fiber cored wire with the covering material is taken out from the downward opening by moving the optical fiber core from the top to the bottom. The optical fiber recoat apparatus according to claim 11 . 2. An optical fiber recoat apparatus according to claim 1, further comprising control means for controlling the moving speed of the arm to an arbitrary set speed. Optical fiber recoat device according to claim 1, further comprising a control means for controlling the number of movements of the arm in any number of settings. A method of applying a re-coating an optical fiber using an optical fiber recoat device in accordance with claim 1 to 14 by injecting coating material to the upper Symbol the upward opening of the hole of the die, the optical fiber By moving the core wire from top to bottom, the coating material is applied to the optical fiber core wire, and the optical fiber core wire coated with the coating material is taken out from the downward opening of the die , and then dried and dried. An optical fiber recoating method comprising curing and coating the optical fiber core wire . Before injecting the covering material into the die, the vertical movement start position and vertical movement end position of the arm are stored in the storage means in advance, and the arm is aligned with the vertical movement start position read from the storage means. 16. The optical fiber recoating method according to claim 15 , wherein a coating material is injected into the die and the arm is moved to a vertical movement end position. The optical fiber recoating method according to claim 15 or 16 , wherein the coating thickness is adjusted by controlling the moving speed and the number of movements of the arm based on the hole diameter of the die. 18. The optical fiber recoating method according to claim 15, wherein the thickness of the coating is targeted to be approximately the same as the thickness of the coating before removal. 16. The optical fiber recoating method according to claim 15, wherein the die and the optical fiber core are aligned on the basis of an image displayed on the image display means.

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