JP2013063890A - Method of producing optical fiber preform and method of producing optical fiber using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing an optical fiber preform at low cost by preventing manhours from increasing, and to provide a method of producing an optical fiber using the same.SOLUTION: The method of producing the optical fiber preform 10P includes: a preparation step P1 of preparing a glass-made intermediate preform19P; and a boring step P2 of boring a hole on the intermediate preform 19P with a drilling tool 50. In the boring step P2, the vibrations from the drilling tool 50 are detected; and how far the hole is shifted is measured based on the detected vibrations.

Description

  The present invention relates to a method for manufacturing an optical fiber preform capable of manufacturing an optical fiber preform at a low cost while suppressing an increase in man-hours, and an optical fiber manufacturing method using the same.

  As a kind of optical fiber, a holey fiber is known in which a plurality of holes are formed in a clad along the longitudinal direction of the optical fiber. In the optical fiber preform for manufacturing the holey fiber, holes serving as hole of the holey fiber are formed along the longitudinal direction of the optical fiber preform.

  Patent Document 1 listed below describes a method for manufacturing such an optical fiber preform. In this optical fiber manufacturing method, a hole is formed in a glass rod that is an intermediate body of an optical fiber preform. In forming the hole, a drill tool having a grindstone having a coarse grain at the tip is usually used, and the hole is formed from one end surface of the glass rod toward the other end surface. As this drill tool, a pipe-shaped drill tool is generally used in order to shorten the processing time.

JP 2002-293562 A

  In recent years, there is a demand for manufacturing an optical fiber using a longer optical fiber preform. However, when the optical fiber preform is long as described above, if the hole is formed in the glass rod as the optical fiber preform using the pipe-shaped drill tool as described above, the drill tool bends during the formation of the hole. As a result, the formed hole may bend beyond an allowable range. In particular, when a pipe-shaped drill tool is used, the drill tool is easily bent, and the hole is easily bent and formed beyond an allowable range.

  As a method of measuring the bending of the hole formed in such a glass rod, a method of observing both end faces of the glass rod can be mentioned. This method observes the hole formation position on both end faces of the glass rod, and measures the bending of the hole from the amount of deviation of the hole formation position on the other end face from the hole formation position on one end face. .

  By the way, if the hole formed in the glass rod is bent from the middle, if the hole deviation amount is outside the allowable range, the remaining part can be used as the optical fiber preform. Can be reduced, and the optical fiber preform can be manufactured at low cost. Therefore, there is a demand to specify the location where the hole deviates beyond the allowable range. However, when using the above measurement method to identify from which position the hole is displaced beyond the allowable range, cut the glass rod gradually from the other end face side, It is necessary to compare the hole formation position on the surface with the hole formation position on one end face and measure the amount of deviation of the hole from these formation positions.

  Such a method requires man-hours for cutting the glass rod and man-hours for measuring the hole formation position on the end face several times in order to measure the bending of the hole. There is a possibility that the material cannot be manufactured at a low cost. Further, in the above measurement method, the hole is formed beyond the allowable range because the hole is formed up to the other end surface of the glass rod regardless of whether the hole is shifted beyond the allowable range. In this case, unnecessary man-hours are required, and there is a possibility that the optical fiber preform cannot be manufactured at low cost.

  Accordingly, the present invention provides an optical fiber preform manufacturing method capable of manufacturing an optical fiber preform inexpensively while suppressing an increase in man-hours, and an optical fiber manufacturing method using the same. For the purpose.

  In order to solve the above problems, the optical fiber preform manufacturing method of the present invention includes a preparation step of preparing an intermediate preform made of a glass body, a drilling step of forming a hole in the intermediate preform with a drill tool, In the drilling step, vibration of the drill tool is detected, and a deviation amount of the hole is measured from the detected vibration.

  The drill tool drills by moving while rotating. When such a tool is bent halfway, vibration due to rotation tends to increase. Therefore, in the optical fiber preform manufacturing method of the present invention, the vibration of the drill tool is detected, and the deviation of the hole is measured based on the magnitude and waveform of the vibration. By measuring the amount of deviation of the hole in this way, it can be easily known during drilling where the hole formed by the drill tool has shifted beyond the allowable range. Therefore, it is possible to easily identify the portion where the hole deviation amount is within the allowable range without cutting the intermediate base material. For this reason, it is possible to suppress the increase in the number of man-hours, specify the portion where the hole shift amount in the intermediate base material is within the allowable range, and manufacture the optical fiber base material at low cost.

  In the drilling step, it is preferable that the hole formation is interrupted when the measured deviation amount of the hole exceeds a predetermined allowable range of the deviation amount of the hole.

  Once the hole exceeds the allowable range, it is rare that the deviation amount of the hole is within the allowable range thereafter. Therefore, when the amount of deviation of the hole exceeds the allowable range, unnecessary man-hours can be reduced by interrupting the formation of the subsequent holes. In addition, when the hole formation is interrupted in this way, a portion in which the deviation amount of the hole in the intermediate base material is within an allowable range is cut off to be an optical fiber base material, and a portion in which no hole is formed On the other hand, drilling is performed again at a correct position to form a hole whose deviation is within an allowable range, thereby forming an optical fiber preform. Therefore, the intermediate | middle base material which becomes useless can be reduced and the preform | base_material for optical fibers can be manufactured cheaply.

  Further, in the drilling step, when the measured deviation amount of the hole exceeds a predetermined range within a predetermined allowable range of the deviation amount of the hole, the feed rate of the drill tool is reduced. Is preferred. Further, in the drilling step, when the measured deviation amount of the hole exceeds a predetermined range within a predetermined allowable range of the deviation amount of the hole, the number of rotations per unit time of the drill tool It is also preferable to raise the value. In the drilling step, when the measured deviation amount of the hole exceeds a predetermined range within a predetermined allowable range of the deviation amount of the hole, cutting water introduced into the hole is introduced. It is also preferable to increase the pressure.

  By reducing the feed rate of the drill tool, increasing the number of revolutions per unit time of the drill tool, or increasing the pressure of the cutting water in this way, even if the drill tool begins to bend and advance, An increase in the amount can be suppressed. Therefore, even if the drill tool begins to bend and advance, the portion where the deviation amount of the formed hole is within the allowable range can be lengthened, and a long optical fiber preform can be manufactured.

  Further, in the drilling step, when the measured deviation amount of the hole exceeds a predetermined range within a predetermined allowable range of the deviation amount of the hole, dressing may be performed on the drill tool. preferable. That is, when the deviation amount of the hole exceeds a predetermined range, it is preferable to take out the drill tool once, dress the drill tool, and drill again.

  With the dressing, the cutting performance of the drill tool is improved as compared with that before the dressing, and even when the hole is bent, it is possible to suppress an increase in the amount of deviation of the hole. Therefore, even if the drill tool begins to bend and advance, the portion where the deviation amount of the formed hole is within the allowable range can be lengthened, and a long optical fiber preform can be manufactured.

  Further, in the drilling step, when the measured deviation amount of the hole exceeds a predetermined range within a predetermined allowable range of the deviation amount of the hole, the tip of the drill tool and the intermediate base material It is preferable that the distance from the upper surface of the intermediate base material to the portion where the drill tool is chucked is shortened.

  By shortening the distance from the intermediate base material to the chucked portion of the drill tool, it is possible to suppress the deflection of the portion exposed to the outside of the intermediate base material in the drill tool, and the amount of deviation of the hole is large It can be suppressed. Therefore, even if the drill tool begins to bend and advance, the portion where the deviation amount of the formed hole is within the allowable range can be lengthened, and a long optical fiber preform can be manufactured.

  The vibration of the drill tool may be detected by detecting the vibration of the intermediate base material by a vibration detection sensor attached to the intermediate base material.

  By attaching the vibration sensor to the intermediate base material, it is possible to prevent the drill tool being processed from being affected by the vibration sensor. Moreover, since a contact-type simple vibration sensor can be used, vibration can be detected at low cost.

  Alternatively, the vibration of the drill tool may be detected by detecting the amount of vibration during rotation of the drill tool using a non-contact displacement sensor.

  By directly detecting the amount of deflection of the drill tool, the vibration of the drill tool can be detected more accurately. Moreover, by using a non-contact sensor, it is possible to prevent the drill tool being processed from being affected by the sensor.

  Alternatively, the vibration of the drill tool may be detected by detecting the vibration of the drilling device with a vibration detection sensor attached to the drilling device that rotates the drill tool.

  By attaching the vibration sensor to the drilling device, it is possible to prevent the drill tool being processed from being affected by the vibration sensor. Moreover, since a contact-type simple vibration sensor can be used, vibration can be detected at low cost.

  Moreover, the manufacturing method of the optical fiber of this invention is equipped with the drawing process which draws the preform | base_material for optical fibers manufactured by one of the manufacturing methods of the preform | base_material for optical fibers mentioned above. .

  According to such an optical fiber manufacturing method, an optical fiber can be manufactured at low cost because an optical fiber preform that is manufactured at low cost while suppressing an increase in man-hours is used.

  As described above, according to the present invention, it is possible to suppress the increase in the number of man-hours and to manufacture the optical fiber preform at a low cost, and to provide an optical fiber using the optical fiber preform. A manufacturing method is provided.

It is a figure which shows the mode of the structure in the cross section perpendicular | vertical to the longitudinal direction of the optical fiber which concerns on 1st Embodiment of this invention. It is a figure which shows the mode of a structure perpendicular | vertical to the longitudinal direction of the preform | base_material for optical fibers for manufacturing the optical fiber of FIG. It is a flowchart which shows the process of the manufacturing method of the optical fiber of FIG. It is a figure which shows the mode of a structure perpendicular | vertical to the longitudinal direction of the intermediate | middle base material prepared by the preparation process shown in FIG. It is a figure which shows the state by which the drill tool and the intermediate | middle base material were set to the drilling apparatus. It is a figure which shows the drill tool used for a drilling process. It is a figure which shows the mode of a punching process. It is a figure which shows the state which the drill tool is curving and advancing. It is a figure which shows the mode of a drawing process. It is a figure which shows the mode of a structure perpendicular | vertical to the longitudinal direction of the optical fiber which concerns on 2nd Embodiment of this invention. It is a figure which shows the mode of the structure in the cross section perpendicular | vertical to the longitudinal direction of the preform | base_material for optical fibers for manufacturing the optical fiber of FIG. It is a figure which shows the mode of a structure in the cross section perpendicular | vertical to the longitudinal direction of the intermediate | middle base material of the optical fiber base material shown in FIG. It is a figure which shows the modification by which the vibration detection sensor was connected to the punching apparatus. It is a figure which shows the modification in the case of detecting the vibration of a drill tool by a non-contact system. It is a figure which shows the mode of the vibration of the drill tool in Example 1. FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a method for producing an optical fiber preform according to the present invention and a method for producing an optical fiber using the same will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram showing a structure in a cross section perpendicular to the longitudinal direction of an optical fiber according to a first embodiment of the present invention.

  As shown in FIG. 1, the optical fiber 10 of the present embodiment includes a core 11, a clad 12 that surrounds the core 11 without a gap, a first coating layer 16 that covers the cladding 12, and a first coating layer that covers the first coating layer 16. And two coating layers 17. An optical fiber in which such a cladding is coated with a coating layer is also called an optical fiber. The clad 12 has a lower refractive index than the core 11, and the clad 12 has a plurality of holes 13 surrounding the core 11 around the core 11. Thus, the optical fiber 10 of this embodiment is a holey fiber having a plurality of holes in the cladding.

  Further, the diameter of the core 11 is, for example, 7 μm to 10 μm, the outer diameter of the clad 12 is, for example, 125 μm, the diameter of the hole 13 is 3 μm to 8 μm, and the diameter of the hole 13 from the center of the core 11 is The distance to the center is 8 μm to 20 μm. In addition, said diameter, an outer diameter, and distance are illustrations, and it does not restrict | limit in particular.

Further, as is, for example, can be mentioned germanium quartz dopant to increase the refractive index of the (Ge) or the like is added (SiO _2), as a material for the clad 12 material constituting the core 11, for example, Examples include pure quartz to which no dopant is added, and quartz to which fluorine (F) that lowers the refractive index is added, and examples of materials constituting the first coating layer 16 and the second coating layer 17 include Examples thereof include different types of ultraviolet curable resins. In addition, said material is an illustration and it does not restrict | limit in particular.

  Such an optical fiber 10 is particularly called a hole assist fiber among holey fibers. When light propagates through the core 11, the confinement effect of the light in the core 11 is enhanced by the holes 13, and the light core 11. Can be prevented, and loss of light propagating through the core 11 can be suppressed.

  FIG. 2 is a diagram showing a state of the structure perpendicular to the longitudinal direction of the optical fiber preform for manufacturing the optical fiber 10 of FIG.

  As shown in FIG. 2, the optical fiber preform 10P has a substantially cylindrical shape, and a rod-shaped core glass body 11P that becomes the core 11 and a rod-shape that surrounds the core glass body 11P and becomes the cladding 12 The clad glass body 12P. The cladding glass body 12P has a plurality of through holes 13P surrounding the core glass body 11P around the core glass body 11P. Such an optical fiber preform 10P is drawn and coated as will be described later, whereby the optical fiber 10 shown in FIG. 1 is obtained.

  Next, the optical fiber preform 10P in FIG. 2 and the method for manufacturing the optical fiber 10 in FIG. 1 will be described.

  FIG. 3 is a flowchart showing the steps of the optical fiber preform 10P and the optical fiber 10 manufacturing method. As shown in FIG. 3, the optical fiber preform 10P is manufactured by a preparation step P1 for preparing an intermediate preform including a core glass body 11P and a clad glass body 12P in which a through hole 13P is not formed, and an intermediate preform. And a drilling step P2 for forming a through hole in the clad glass body 12P. And the manufacturing method of the optical fiber 10 is further provided with the drawing process P3 which draws the preform | base_material for optical fibers manufactured in this way.

<Preparation process P1>
FIG. 4 is a diagram showing a state of the structure perpendicular to the longitudinal direction of the intermediate base material prepared by the preparation step P1. As shown in FIG. 4, the intermediate base material 19P is composed of a core glass body 11P shown in FIG. 2 and a clad glass body 12P surrounding the core glass body 11P. However, the through hole 13P of the optical fiber preform 10P shown in FIG. 2 is not formed in the intermediate preform 19P.

  In preparation of the intermediate | middle base material 19P, the method of forming the core glass body 11P and the clad glass body 12P continuously is mentioned, for example. Such a method is not particularly limited, and examples thereof include a method using a soot process such as an MCVD method, a VAD method, and an OVD method. In this way, an intermediate base material 19P shown in FIG. 4 is obtained.

<Punching process P2>
Next, preparation is made for forming the through hole 13P along the longitudinal direction of the clad glass body 12P of the prepared intermediate base material 19P.

  FIG. 5 is a diagram illustrating a state in which the drill tool 50 and the intermediate base material 19P are set in a drilling device for forming a hole in the intermediate base material 19P. As shown in FIG. 5, the drilling device 70 includes a spindle 71 and a drill chuck 72 rotated by the spindle 71, and the drill tool 50 is chucked on the drill chuck 72.

  FIG. 6 is a view showing the drill tool 50. As shown in FIG. 6, the drill tool 50 includes a pipe 52 and a cutting portion 51 provided at the tip of the pipe 52 as main components.

  The pipe 52 has a cylindrical shape, and has an outer diameter slightly smaller than the diameter of the through hole formed in the intermediate base material 19P in this step. The outer diameter of the pipe 52 is preferably smaller by 0.1 to 0.3 mm than the diameter of the hole formed in the intermediate base material 19P. The cutting part 51 has a cylindrical shape and has an outer diameter similar to the diameter of the through hole formed in the intermediate base material 19P in this step. Therefore, the cutting part 51 has an outer diameter larger than the outer diameter of the pipe 52. In addition, if the difference between the outer diameter of the pipe 52 and the outer diameter of the cutting part 51 is 0.3 mm or less, the strength of the pipe 52 can be prevented from being weakened, and this difference is preferably 0.1 mm or more. If so, it is preferable that the pipe 52 can be appropriately prevented from being clogged in the holes formed in the intermediate base material 19P when drilling. Further, the through holes of the pipe 52 and the cutting part 51 are connected to each other, and thus the through hole 53 is formed in the drill tool 50.

  Such a drill tool 50 is chucked by the drill chuck 72 as described above. The drilling device 70 is configured to be able to be chucked at an arbitrary place in the pipe 52 of the drill tool 50 by a mechanism (not shown) even if the drill tool 50 is long. As shown in FIG. 5, before the drilling is performed, the length from the tip of the drill tool 50 to the chucking by the drill chuck 72 is sufficiently shorter than the length of the intermediate base material 19P. Is preferred. Here, when the tip of the drill tool 50 is in contact with the intermediate base material 19P, the distance from the upper surface of the intermediate base material 19P to the portion where the drill tool 50 is chucked is defined as a free gripping length L. Prior to drilling, since no hole is formed in the intermediate base material 19P, the free gripping length L is equal to the distance from the tip of the drill tool 50 to the tip of the drill chuck 72. By shortening the free gripping length L, the bending of the pipe 52 of the drill tool 50 can be reduced. By reducing the bending of the pipe 52 in this way, the bending of the hole formed in the intermediate base material 19P can be reduced. For example, at the start of drilling, the free gripping length L may be the length of the cutting portion 51 of the drill tool 50 so that the pipe 52 is not exposed. During the chucking of the drill tool 50 to the drill chuck 72, the tip of the drill tool 50 does not need to be in contact with the clad glass body 12P.

  In a state where the drill tool 50 is chucked on the drill chuck 72, the amount of deflection of the drill tool 50 at a location 15 mm away from the drill chuck 72 is preferably 40 μm or less. In order to measure the amount of deflection of the drill tool 50, after the drill tool 50 is chucked to the drill chuck 72, the drill tool 50 is slowly rotated together with the drill chuck 72, for example, using a dial gauge. What is necessary is just to measure the run-out amount of the pipe 52 in the vicinity of the 50 cutting parts 51. When the amount of deflection of the drill tool 50 is 40 μm or less, the amount of displacement of the position of the hole formed by the drilling can be reduced. Further, when the amount of deflection of the drill tool 50 is 40 μm or less as described above, vibration due to the deflection of the drill tool 50 during drilling can be suppressed.

  Further, in this step, the vibration detection sensor 81 is attached to the intermediate base material 19P before being punched. The vibration detection sensor 81 detects and outputs the vibration when the intermediate base material 19P vibrates. Examples of the vibration detection sensor 81 include an AE sensor (Acoustic Emission sensor) and an acceleration sensor. As the acceleration sensor, an acceleration sensor such as a capacitance detection method, a piezoresistance method, a heat detection method, or a semiconductor method can be used. Among them, the capacitance detection type acceleration sensor is preferable from the viewpoint of excellent temperature characteristics because the sensor element portion is made of a stable substance such as silicon or glass. Note that the vibration detection sensor 81 is preferably attached with an adhesive having a small elastic deformation from the viewpoint of easily detecting the vibration of the intermediate base material 19P.

  The vibration detection sensor 81 is electrically connected to the control unit 80, and the control unit 80 receives information related to the vibration of the intermediate base material 19P output from the vibration detection sensor 81 and, as will be described later, The amount of deviation of the holes formed in the material 19P is calculated.

  Thus, preparation for forming the through hole 13P in the intermediate base material 19P is completed.

  Next, a hole is formed in the intermediate base material 19P. FIG. 7 is a diagram showing a state of perforation for forming a hole. As shown in FIG. 7, in this step, the drill tool 50 is pushed along the longitudinal direction of the clad glass body 12 </ b> P while rotating the drill tool 50 about the axis, and the cutting water is cut from the pipe 52 side of the through hole 53. Is introduced. The number of rotations per unit time of the drill tool 50 is, for example, 3000 rpm, the feed rate at which the drill tool 50 travels is, for example, 30 mm / min, and the pressure of the cutting water is, for example, 1.0 MPa. It is said. In addition, as cutting water, a water-soluble cutting fluid can be mentioned, for example.

  The cutting water introduced in this way flows through the through hole 53 and flows out from the tip of the cutting part 51. In the state in which the cutting part 51 has advanced to the middle of the clad glass body 12P, since the holes of the clad glass body 12P do not penetrate, the cutting water flowing out from the tip of the cutting part 51 loses its place and the cutting part 51 It flows backward from the inner wall surface of the clad glass body 12P, and is discharged from the side where the drill tool 50 is inserted by the drill tool 50. Therefore, until the hole formed in the intermediate base material 19P penetrates, the temperature of the cladding glass body 12P excessively increases due to the friction between the cutting portion 51 and the cladding glass body 12P. The glass waste generated by the drilling is discharged from the side where the drill tool 50 is inserted together with the cutting water.

  As described above, when the initial free gripping length L is shorter than the length of the intermediate base material 19P, the drill chuck 72 approaches the end surface of the intermediate base material 19P by drilling, and the free gripping length L gradually decreases. Before the drill chuck 72 contacts the intermediate base material 19P, the drilling is temporarily stopped. Then, the chucking is performed again so that the distance from the tip of the drill tool 50 to the portion to be chucked becomes longer than the initial state. At this time, it is preferable to perform chucking so that the free gripping length L is longer than the initial free gripping length. However, the free gripping length L in a state in which a certain drilling is performed and a hole having a certain length is formed means that the tip of the drill tool 50 is the intermediate base material 19P at the end on the back side of the formed hole. Is a distance from the upper surface of the intermediate base material 19P to the portion where the drill tool 50 is chucked. Then, after the drill tool 50 is re-chucked, the intermediate base material 19P is punched again. As described above, when the free gripping length L is shorter than the length of the intermediate base material 19P, the chucking and drilling of the drill tool 50 are repeated to form deep holes in the intermediate base material 19P.

  During such drilling, vibration due to rotation of the drill tool 50 occurs. Since the vibration propagates to the intermediate base material 19P, the vibration detection sensor 81 detects the vibration of the intermediate base material 19P. Information about the detected vibration of the intermediate base material 19P is sent to the control unit 80, and the control unit 80 receives this information. Next, the control unit 80 obtains the magnitude and waveform of the vibration of the drill tool 50 based on information from the vibration detection sensor 81 by calculation. Specifically, the control unit 80 has a table showing the relationship between the magnitude of the vibration of the intermediate base material 19P and the magnitude of the vibration of the drill tool 50, and the vibration of the drill tool 50 is used using this table. The size and waveform are calculated. Thus, vibration of the drill tool 50 is detected.

  Further, the control unit 80 obtains the degree of bending of the drill tool 50 by calculation based on the magnitude and waveform of the vibration of the drill tool 50. FIG. 8 is a diagram illustrating a state in which the drill tool 50 is bent and progressing. However, in FIG. 8, the ratio of each part is changed from the actual scale for easy understanding. When the drill tool 50 goes straight and a hole is formed at the position of the hole that should be originally formed, the vibration of the drill tool 50 is small and the waveform also has a constant periodic shape. However, as shown in FIG. 8, when the drill tool 50 bends from the middle and the hole to be formed deviates from the position ARc of the hole to be originally formed indicated by the dotted line in the drawing, the amount of deviation of the formed hole is large. Accordingly, the vibration of the drill tool 50 increases and the waveform is disturbed. The control unit 80 further includes a table indicating the relationship between the magnitude of the vibration of the drill tool 50 and the shape of the waveform and the deviation amount of the hole. Using this table, the deviation amount of the hole is determined. Is calculated. In this way, the displacement amount of the hole is measured. As described above, if the amount of vibration at a location 15 mm away from the drill chuck 72 of the drill tool 50 is 40 μm or less, vibration caused by the vibration of the drill tool 50 during drilling can be suppressed. Noise to the sensor 81 can be suppressed. Therefore, the bending degree of the drill tool 50 at the time of drilling can be calculated | required more accurately. Further, if the above table further has a relationship between the amount of deflection of the drill tool 50 and the amount of deviation of the hole, the amount of deviation of the hole can be obtained by taking into account the amount of deflection of the drill tool 50. This is preferable because it is possible. For example, the table has a relationship between the magnitude of vibration, the amount of vibration of the drill tool 50, and the amount of displacement of the hole, and the amount of displacement of the hole is obtained using this table.

  A table showing the relationship between the magnitude of the vibration of the intermediate base material 19P and the magnitude of the vibration of the drill tool 50, and a table showing the relation between the magnitude of the vibration of the drill tool 50 and the waveform shape and the amount of deviation of the hole. Are obtained in advance by experiments or the like and stored in a table.

  When the hole deviation amount is smaller than the predetermined hole deviation amount allowable range ARa shown in FIG. 8, the hole is formed deeper by drilling and finally penetrated. Thus, in the state where the through holes 13P are formed in the intermediate base material 19P and a predetermined number of the through holes 13P are formed, the inner walls forming the respective through holes 13P are polished as necessary. The optical fiber preform 10P shown in FIG.

  On the other hand, as shown in FIG. 8, when the drill tool 50 is bent from the middle and the deviation amount of the hole measured by the control unit 80 exceeds the allowable range ARa of the deviation amount of the hole, for example, the control unit 80 An alarm is sounded by means that do not. In this case, the operator of the punching device 70 stops the punching device 70 and stops forming the hole. Alternatively, when the deviation amount of the hole measured by the control unit 80 exceeds the allowable range ARa of the deviation amount of the hole, the control unit 80 automatically stops the drilling device 70 and the formation of the hole is automatically stopped. May be. As described above, once the hole exceeds the allowable range ARa, it is rare that the deviation amount of the hole returns to the allowable range ARa after that. Therefore, when the amount of deviation of the hole exceeds the allowable range ARa, the formation of the subsequent holes is interrupted as described above, so that unnecessary drilling is not performed and unnecessary man-hours can be reduced.

  In this case, after the formation of the hole is interrupted, the drill tool 50 is extracted from the hole, and the part in which the deviation amount of the hole in the intermediate base material 19P is within the allowable range ARa and the part in which the formation of the hole is not completed Disconnect. Of the separated intermediate base material 19P, the side where the hole is within the allowable range ARa forms other holes as necessary, and further polishes the inner walls forming the respective holes as necessary. The optical fiber preform 10P shown in FIG.

  On the other hand, in the separated intermediate base material 19P, the portion in which the hole is not properly formed due to the interruption of the drilling is separated as necessary. Then, the remaining part is perforated again in the same manner as the above-described perforation to the intermediate base material 19P. And after all the through-holes 13P are formed appropriately, the inner wall which forms each through-hole 13P is grind | polished as needed, and it is set as the optical fiber base material 10P shown in FIG.

  When the formation of the hole is interrupted in this way, as described above, the hole deviation amount in the intermediate base material 19P cuts off the portion within the allowable range ARa, and after forming other necessary holes, In addition to the fiber preform, a hole is formed by drilling again at the correct position in the portion where the cut holes have not yet been drilled to obtain an optical fiber preform. By doing so, it is possible to reduce the intermediate base material that is wasted and to manufacture the optical fiber base material at low cost.

  Moreover, as shown in FIG. 8, when the drill tool 50 bends from the middle, a means for increasing the distance until the hole displacement amount reaches the allowable range ARa may be provided. Specifically, when the deviation amount of the hole measured by the control unit 80 exceeds a predetermined range ARp within the tolerance range ARa of the deviation amount of the hole, the feed speed that is the speed at which the drill tool 50 is advanced is reduced. For example, as described above, when the feed speed at which the drill tool 50 travels is 30 mm / min, this speed is reduced to 15 mm / min, for example. In this way, by reducing the feed rate, the amount of cutting of the intermediate base material by the cutting unit 51 of the drill tool 50 per unit rotation is reduced, and the diamond grindstone or the like on the surface of the tip of the cutting unit 51 is reduced. Damage is reduced. For this reason, even if a drill tool begins to bend and advance, it can control that the amount of deviation of a hole becomes large. Therefore, even if the drill tool is bent and advanced, the portion where the deviation amount of the formed hole is within the allowable range can be lengthened, and the optical fiber preform 10P can be manufactured as long as possible.

  Moreover, when the deviation | shift amount of the hole measured by the control part 80 exceeds predetermined range ARp in the tolerance | permissible_range ARa of the deviation | shift amount of a hole, you may raise the rotation speed per unit time of the drill tool 50. FIG. For example, as described above, when the rotation speed per unit time of the drill tool 50 is set to 3000 rpm, the rotation speed is increased to, for example, 4000 rpm. As the number of rotations per unit time of the drill tool 50 increases, the amount of cutting of the intermediate base material by the cutting unit 51 of the drill tool 50 per unit rotation is reduced, and diamond on the tip surface of the cutting unit 51 Damage to the grinding wheel is reduced. For this reason, even if a drill tool begins to bend and advance, it can control that the amount of deviation of a hole becomes large. Therefore, even in this case, even if the drill tool is bent and advanced, the portion where the deviation amount of the formed hole is within the allowable range can be lengthened, and the optical fiber preform 10P is manufactured as long as possible. be able to.

  Moreover, when the deviation | shift amount of the hole measured by the control part 80 exceeds predetermined range ARp in the tolerance | permissible_range ARa of the deviation | shift amount of a hole, you may raise the pressure of the cutting water introduce | transduced in a hole. For example, as described above, when the pressure of the cutting water introduced into the hole is 0.7 MPa, the pressure is increased to, for example, 1.4 MPa. By increasing the pressure of the cutting water, it becomes easy to discharge the chips of the intermediate base material accompanying the drilling that disturbs the cutting from the hole, and the cooling effect is increased to the surface of the tip portion of the drill tool 50. Even if the drill tool starts to bend and advance, it is possible to prevent the hole displacement from becoming large. Therefore, even in this case, even if the drill tool is bent and advanced, the portion where the deviation amount of the formed hole is within the allowable range can be lengthened, and the optical fiber preform 10P is manufactured as long as possible. be able to.

  Further, when the hole deviation amount measured by the control unit 80 exceeds a predetermined range ARp within the hole deviation amount allowable range ARa, the drill tool 50 may be dressed. Specifically, when a predetermined range ARp within the allowable range ARa of the hole deviation amount is exceeded, the drilling is temporarily stopped, the drill tool 50 is extracted from the hole, and dressing is performed on the cutting portion 51. By applying dressing, the abrasive grains that have become blunt on the surface of the cutting part 51 are removed, and new abrasive grains appear on the surface. Thus, the cutting force of the drill tool 50 is improved. As described above, the drill tool 50 with improved cutting force can lengthen the portion where the amount of deviation of the hole to be formed is within the allowable range even if the drill tool is bent and advanced. The base material 10P can be manufactured.

  Moreover, when the deviation | shift amount of the hole measured by the control part 80 exceeds predetermined range ARp in the tolerance | permissible_range ARa of the deviation | shift amount of a hole, you may shorten the free grip length L of the drill tool 50. FIG. Specifically, when the predetermined range ARp within the allowable range ARa of the hole deviation amount is exceeded, the drilling is temporarily stopped, and the intermediate base material 19P in the case where the tip of the drill tool 50 and the intermediate base material 19P are in contact with each other. Chucking is performed again so that the distance from the upper surface to the portion where the drill tool 50 is chucked is shortened. By reducing the free gripping length L in this way, the pipe 52 can be prevented from being bent between the upper surface of the intermediate base material 19P and the portion where the drill tool 50 is chucked, and the drill tool is bent. As a result, it is possible to lengthen the portion where the amount of deviation of the formed hole is within the allowable range, and it is possible to manufacture the optical fiber preform 10P that is as long as possible.

  In addition, when the deviation | shift amount of the hole measured by the control part 80 exceeds predetermined range ARp in the tolerance | permissible_range ARa of deviation | shift amount of a hole, the fall of the feed rate of the above-mentioned drill tool 50, and the unit of the drill tool 50 You may combine suitably the raise of the rotation speed per time, the raise of the pressure of cutting water, the dressing of the drill tool 50, and shortening of the free holding length L. FIG.

  Then, after applying these means, if the hole deviation measured by the control unit 80 exceeds the hole deviation amount allowable range ARa, the hole formation may be stopped in the same manner as described above. . Then, in the same manner as described above, the portion where the amount of deviation of the hole in the intermediate base material 19P is within the allowable range ARa is separated from the portion where the formation of the hole is not completed, and each portion separated is necessary. What is necessary is just to make each separated part 10P as optical fiber base materials, such as by forming a hole or polishing the inner wall where each through-hole 13P is formed.

<Drawing process P3>
FIG. 9 is a diagram illustrating a state of the drawing process P3.

  First, as a preparation stage for performing the drawing process P3, a plurality of glass tubes are connected to the optical fiber preform 10P manufactured by the preparation process P1 and the drilling process P2. The plurality of glass tubes are connected to the optical fiber preform 10P such that the through holes of the respective glass tubes and the respective through holes 13P of the optical fiber preform 10P communicate with each other. Next, the inside of the through hole 13P is etched. In this etching process, small irregularities in the through hole 13P are removed, and impurities such as hydroxyl groups are removed from the inner wall of the through hole 13P. The etching solution used for the etching process is introduced into each through hole 13P of the optical fiber preform 10P through the through hole of the glass tube connected to the optical fiber preform 10P.

  Next, the optical fiber preform 10P that has been subjected to the etching process is placed in the spinning furnace 110. In FIG. 10, the glass tube is omitted. And the heating part 111 of the spinning furnace 110 is made to generate heat, and the optical fiber preform 10P is heated. At this time, the lower end of the optical fiber preform 10P is heated to, for example, 2000 ° C. and is in a molten state. Then, the glass melts from the optical fiber preform 10P, and the glass is drawn. The drawn molten glass immediately solidifies as it exits the spinning furnace 110, and the core glass body 11 </ b> P becomes the core 11, the clad glass body 12 </ b> P becomes the clad 12, and the core 11 and the clad 12 are configured. Optical fiber. Thereafter, the optical fiber passes through the cooling device 120 and is cooled to an appropriate temperature. When entering the cooling device 120, the temperature of the optical fiber is, for example, about 1800 ° C., but when exiting the cooling device 120, the temperature of the optical fiber is, for example, 40 ° C. to 50 ° C. In the drawing step P3, a gas such as an inert gas for pressure control is passed from the plurality of glass tubes previously connected to the optical fiber preform 10P to the respective through holes 13P of the optical fiber preform 10P. Is introduced. In this way, it is possible to prevent variations in the diameter of the hole 13 of the optical fiber after drawing by drawing while adjusting the pressure in each through hole 13P of the optical fiber preform 10P.

  Next, the optical fiber passes through the coating device 131 containing the ultraviolet curable resin to be the first coating layer 16 and is coated with the ultraviolet curable resin. Further, when passing through the ultraviolet irradiation device 132 and being irradiated with ultraviolet rays, the ultraviolet curable resin is cured and the first coating layer 16 is formed. Next, the optical fiber passes through the coating device 133 containing the ultraviolet curable resin to be the second coating layer 17 and is coated with the ultraviolet curable resin. Further, when passing through the ultraviolet irradiation device 134 and being irradiated with ultraviolet rays, the ultraviolet curable resin is cured and the second coating layer 17 is formed, and the optical fiber 10 shown in FIG. 1 is obtained.

  Then, the direction of the optical fiber 10 is changed by the turn pulley 141, and the optical fiber 10 is taken up by the reel 142.

  Thus, the optical fiber 10 which is a holey fiber shown in FIG. 1 is manufactured.

  As described above, according to the method for manufacturing the optical fiber preform 10P according to the present embodiment, the vibration of the drill tool 50 is detected, and the deviation amount of the hole is measured based on the magnitude of the vibration. By measuring the amount of deviation of the hole in this way, it is possible to easily know where the hole formed by the drill tool 50 has shifted beyond the allowable range ARa during drilling. Therefore, it is possible to easily identify the portion where the hole deviation amount is within the allowable range ARa without cutting the intermediate base material 19P. For this reason, as a whole, the increase in the number of man-hours is suppressed, and the portion where the deviation amount of the hole in the intermediate base material 19P is within the allowable range ARa can be specified, and the optical fiber base material 10P can be manufactured at low cost. . And by using this optical fiber preform 10P, the optical fiber 10 can be manufactured at low cost.

(Second Embodiment)
Next, a second embodiment of the present invention will be described in detail with reference to FIGS. In addition, about the component which is the same as that of 1st Embodiment, or an equivalent component, the overlapping description is abbreviate | omitted except the case where it attaches | subjects the same referential mark and demonstrates in particular. FIG. 10 is a view showing a state of the structure perpendicular to the longitudinal direction of the optical fiber according to the second embodiment of the present invention.

  As shown in FIG. 10, the optical fiber 20 of the present embodiment includes a core 21, a cladding 22 that covers the core 21, a first coating layer 26 that covers the cladding 22, and a second coating that covers the first coating layer 26. And a coating layer 27. The clad 22 is provided with a plurality of high refractive index portions 24 surrounding the core 21, and a band gap region 28 is formed by the plurality of high refractive index portions 24. Specifically, some high refractive index portions 24 are arranged in a hexagonal shape so as to surround the core 21. The other high refractive index portions 24 are arranged in a triangular lattice pattern with reference to the high refractive index portions 24 arranged in a hexagonal shape. The region where the high refractive index portions 24 are arranged is a band gap region 28. Thus, the optical fiber 20 of this embodiment is a photonic bandgap fiber. In the present embodiment, the periodic structure of the high refractive index portion 24 in the band gap region 28 is four layers as shown in FIG. 10, but the periodic structure may be other than four layers.

  The diameter and material of the core 21 are not particularly limited, but are the same as the core 11 of the optical fiber 10 of the first embodiment, for example.

The outer diameter of the cladding 22 and the refractive index and material other than the high refractive index portion 24 of the cladding 22 are not particularly limited. For example, the outer diameter, the refractive index, and the material of the cladding 12 of the optical fiber 10 according to the first embodiment. The same is said. Further, the refractive index of each high refractive index portion 24 is higher than that of the portion other than the high refractive index portion 24 of the cladding 22. Examples of such a material for the high refractive index portion 24 include quartz (SiO ₂ ) to which a dopant for increasing the refractive index such as germanium (Ge) is added.

  The outer diameter, refractive index, and material of the first coating layer 26 and the second coating layer 27 are not particularly limited. For example, the first coating layer 16 and the second coating layer of the optical fiber 10 of the first embodiment are used. The refractive index and material of the layer 17 are the same.

  In such an optical fiber 20, when light propagates to the core 21, for example, the light confinement effect is enhanced by the band gap region 28, and light can be prevented from leaking from the core 21. Loss can be suppressed.

  FIG. 11 is a view showing a structure in a cross section perpendicular to the longitudinal direction of the optical fiber preform for manufacturing the optical fiber 20 of FIG.

  As shown in FIG. 11, the optical fiber preform 20P has a substantially columnar shape, and a rod-shaped core glass body 21P that becomes the core 21 and a rod-shaped clad glass that covers the core glass body 21P. The body 22P and the clad glass body 22P are provided so as to surround the core glass body 21P, and are composed of a rod-shaped high refractive index glass body 24P that becomes the high refractive index portion 24. Such an optical fiber preform 20P is drawn and coated as will be described later, whereby the optical fiber 20 shown in FIG. 11 is obtained.

  Next, a method for manufacturing the optical fiber preform 20P of FIG. 11 and the optical fiber 20 of FIG. 10 will be described.

  First, as in the first embodiment, the preparation step P1 is performed to prepare an intermediate base material in which no through-hole is formed in the clad glass body. Next, the punching process P2 is performed in the same manner as in the first embodiment. However, in the punching step P2, the through hole 23P is formed at a location corresponding to the high refractive index glass body 24P shown in FIG. In the drilling step P2 in the present embodiment, similarly to the drilling step P2 in the first embodiment, when the amount of deviation of the formed holes exceeds the allowable range, the subsequent hole formation is interrupted. Then, if necessary, the portion where the amount of deviation of the formed hole is within the allowable range may be separated from the portion outside the allowable range. Similarly to the first embodiment, when the drill tool is bent from the middle, a means for increasing the distance until the hole displacement amount reaches the allowable range may be applied. Thus, an intermediate base material 29P in which the through holes 23P are formed as shown in FIG. 11 is obtained.

<Insertion process>
Next, in the present embodiment, glass rods having a refractive index higher than that of the clad glass body are inserted into the respective through holes 23P. At this time, the diameter of the glass rod is made smaller than the diameter of the through hole 23P so that the glass rod does not rub against the inner wall surface of the clad glass body 22P during insertion. Thus, the intermediate base material 29P is in a state in which the glass rod with a high refractive index is inserted into each through hole 23P.

<Collapse process>
Next, the intermediate base material 29P in which the glass rod is inserted into each through hole 23P is put into a vacuum furnace and collapsed. That is, an unnecessary space of the through hole 23P between the glass rod and the inner wall surface of the clad glass body 22P is crushed to integrate the glass rod and the clad glass body 22P. Thus, the glass rod is made into the high refractive index glass body 24P shown in FIG. 11, and the optical fiber preform 20P shown in FIG. 11 is obtained.

  Next, the core glass body 21P becomes the core 21, the cladding glass body 22P becomes the cladding 22, and the high refractive index glass body 24P becomes the high refractive index portion by performing the drawing step P3 in the same manner as in the first embodiment. 24. Then, the cladding 22 is covered with the first coating layer 26 and the second coating layer 27 in the same manner as the cladding 12 is coated with the first coating layer 16 and the second coating layer 17 in the first embodiment. 11 is obtained.

  Even when the glass rod is inserted into the formed through hole as in the method of manufacturing the optical fiber preform according to the present embodiment, the hole formed by the drill tool 50 is displaced beyond the allowable range ARa. Since it can be easily known during drilling, it is possible to manufacture the optical fiber preform 20P at a low cost while suppressing an increase in man-hours as a whole. By using this optical fiber preform 20P, the optical fiber 10 can be manufactured at low cost.

  The present invention has been described above by taking the first and second embodiments as examples, but the present invention is not limited to these.

  Specifically, the optical fiber preform manufacturing method and the optical fiber manufacturing method of the present invention are not limited to the above-described embodiments, and include a step of forming holes in the process of manufacturing the optical fiber preform. The optical fiber preform manufacturing method and optical fiber manufacturing method can also be applied to optical fiber preform manufacturing methods having other structures.

  For example, in the above embodiment, the through holes 13P and 23P are formed in the drilling step P2, but the holes are not necessarily through holes.

  Further, in the optical fiber 10 that is the holey fiber of the first embodiment, the size, number, and arrangement of the holes may be changed as long as the optical fiber has a plurality of holes around the core. For example, the hole size and arrangement may be the same as the high refractive index portion 24 of the optical fiber of the second embodiment, and a holey fiber as a photonic bandgap fiber may be used.

  Further, for example, the optical fiber 20 as the photonic band gap fiber of the second embodiment has a core 21, but the core 21 is not an essential configuration. For example, the optical fiber 20 does not have the core 21 and has a band gap. The core region may be formed by the region 28. Alternatively, the band gap region 28 may be disposed so as to sandwich the core 21 by forming a set of two band gap regions in which a plurality of high refractive index portions 24 are gathered without surrounding the core 21.

  Further, in the photonic band gap fiber of the second embodiment, a low refractive index portion having a refractive index lower than that of the portion other than the high refractive index portion 24 of the cladding 22 can be used instead of the high refractive index portion 24.

  In the drilling step P2, the drill tool 50 provided with the through hole 53 is used, but other drill tools may be used.

  Moreover, in the said embodiment, although each optical fiber has a 1st coating layer and a 2nd coating layer, a 1st coating layer is not an essential structure but a 1st coating layer and a 2nd coating layer. At least one of the layer and the second coating layer may be absent.

  Moreover, in the said embodiment, although the vibration detection sensor was connected to the intermediate | middle base material, you may connect a vibration detection sensor to another place in this invention. FIG. 13 is a diagram in which vibration detection sensors are connected to such other places. As shown in FIG. 13, this modification is a modification in which the vibration detection sensor 81 is connected to the punching device 70. Also in this case, as the drill tool 50 bends from the middle and the formed hole is displaced from the position of the hole to be originally formed, the vibration of the drill tool 50 increases and the vibration waveform is disturbed. This vibration is transmitted to the punching device 70 and detected and output by the vibration detection sensor 81. In the same manner as in the first embodiment, the control unit 80 obtains the magnitude and waveform of the vibration of the drill tool 50, and obtains the deviation amount of the hole from the magnitude and waveform of the vibration. However, since the vibration is transmitted differently between the case where the vibration of the drill tool 50 is transmitted to the intermediate base material 19P and the case where the vibration is transmitted to the drilling device 70, the table of the control unit 80 in this modification is the same as that of the first embodiment. Not the case.

  According to such a modification, it is possible to prevent the drill tool 50 being processed from being affected by the vibration detection sensor 81 by attaching the vibration detection sensor 81 to the drilling device 70. Moreover, since a contact-type simple vibration sensor can be used, vibration can be detected at low cost.

  Further, the vibration of the drill tool 50 may be detected without contact. FIG. 14 is a view showing a modification in which vibration of the drill tool 50 is detected in such a non-contact manner. As shown in FIG. 14, in this modification, a displacement of the drill tool 50 is detected by a non-contact displacement sensor 82. Examples of such a non-contact type displacement sensor 82 include those using an eddy current method, an optical method, an ultrasonic method, and a laser focus method. The magnitude and waveform of the vibration of the drill tool 50 are obtained from the magnitude of the displacement of the drill tool detected by the non-contact displacement sensor 82 and received by the control unit 80, and the hole is determined from the magnitude and waveform of the vibration. Deviation amount is required. Also in this case, the control unit 80 has a table that is matched with the non-contact displacement sensor 82.

  According to such a modification, the vibration of the drill tool 50 can be detected more accurately by directly detecting the amount of deflection of the drill tool 50. Further, by using a non-contact sensor, it is possible to prevent the drill tool 50 being processed from being affected by the sensor.

  Further, in the above-described embodiment and modification, the amount of deviation of the hole is measured from the magnitude of vibration of the drill tool and the waveform of the vibration, but only the magnitude of the vibration of the drill tool or only the waveform of the vibration is used to measure the hole. The amount of deviation may be measured.

  Hereinafter, the content of the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1
An intermediate base material made of quartz having a cylindrical shape and a diameter of 100 mm and a length of 1000 mm was prepared. As shown in FIG. 5, the intermediate base material was set in a perforating apparatus, and an AE sensor was connected to the intermediate base material. Then, drilling was performed using a drill tool having a length of 1100 mm and an outer diameter of the cutting portion of 3.0 mm until the hole penetrated.

  Here, the specified value of the hole displacement was set to 0.20 mm. Note that the amount of deviation of the hole is the difference between the position of the actually formed hole and the position of the designed hole. Further, the specified value is an amount used for verifying the effect of the present invention, and even a deviation amount exceeding the specified value is not a problem as long as it does not exceed the allowable range.

  During drilling, the vibration of the drill tool was detected based on the vibration of the intermediate base material obtained from the AE sensor. The result is shown in FIG.

  As shown in FIG. 15, when the length of the hole (drilling length) exceeds 700 mm, the vibration of the drill tool is a threshold set in advance as the magnitude of the vibration of the drill tool when exceeding the specified value of the deviation amount of the hole. It has been shown that it grows beyond.

Next, the intermediate base material penetrating the hole was cut at a plurality of locations, and the position of the hole on the end surface of the cut intermediate base material was observed with an optical microscope to measure the amount of deviation of the hole. The results are shown in Table 1.

  As shown in Table 1, it was shown that when the hole length exceeded 700 mm, the displacement amount of the hole exceeded 0.20 mm.

  From the above, it was found that the measurement result of the hole deviation amount according to the present invention shown in FIG. 15 coincides with the measurement result of the hole deviation amount using the optical microscope.

  From this, it can be seen that, according to the present invention, it is possible to measure that the hole exceeds the allowable range without cutting the base material by setting the specified value in the present example as the upper limit of the allowable range of the deviation of the hole. It was. Therefore, by using the present invention, it is considered that the increase in the number of man-hours is suppressed and the optical fiber preform can be manufactured at a low cost.

(Example 2)
An intermediate base material made of quartz having a cylindrical shape with a diameter of 150 mm and a length of 900 mm was prepared. Next, a drill tool having a length of 1000 mm and an outer diameter of the cutting portion of 3.0 mm was chucked so that the amount of deflection at a location 15 mm away from the drill chuck was 10 μm. Then, while maintaining this deflection, the chucking is repeated so that the free grip length becomes 55 mm, until the rotation speed is 4000 rpm, the feed speed of the drill tool is 30 mm / min, and the hole penetrates the intermediate base material. Perforated.

  As a result, the maximum value of the hole displacement amount was 0.21 mm. As described above, if the specified value of the deviation amount of the hole measured using the AE sensor is set to 0.20 mm, the deviation amount of the drill tool exceeds the threshold value of the drill tool exceeding the specified value. It became small.

Next, under the same conditions as described above, chucking was performed so that the runout amount was as shown in Table 2, and drilling was performed in the same manner as described above using a drill tool of each runout amount. The results are shown in Table 2.

  As shown in Table 2, if the amount of deflection at a location 15 mm away from the drill chuck of the drill tool is 40 μm or less, even if the through hole is formed in the intermediate base material having a length of 900 mm, the amount of displacement of the hole is 0. It was found to be smaller than 60 and within an allowable range as a deviation amount of a normal base material.

  As described above, according to the present invention, it is possible to suppress the increase in the number of man-hours and to manufacture the optical fiber preform at a low cost, and to provide an optical fiber using the optical fiber preform. A manufacturing method is provided and is particularly useful in the manufacture of holey fibers.

10 ... Optical fiber (Holy fiber)
DESCRIPTION OF SYMBOLS 11, 21 ... Core 12, 22 ... Cladding 13 ... Hole 16, 26 ... First coating layer 17, 27 ... Second coating layer 10P, 20P ... Mother for optical fiber Material 11P, 21P ... Core glass body 12P, 22P ... Clad glass body 13P, 23P ... Through hole 19P, 29P ... Intermediate base material 20 ... Optical fiber (photonic band gap fiber)
24 ... High refractive index portion 28 ... Band gap region 24P ... High refractive index glass body 50 ... Drill tool 51 ... Cutting portion 52 ... Pipe 53 ... Through-hole 70 ... -Drilling device 71 ... Spindle 72 ... Drill chuck 80 ... Control unit 81 ... Vibration detection sensor 82 ... Non-contact displacement sensor 110 ... Spinning furnace 111 ... Heating unit 120 ··· Cooling device 131 ··· Coating device 132 · · · UV irradiation device 133 ··· Coating device 134 · · · UV irradiation device 141 ··· Turn pulley 142 ··· Reel P1 · · · Preparation step P2 ···・ Punching process P3 ... Drawing process

Claims (11)

A preparation step of preparing an intermediate base material made of a glass body;
A drilling step of forming a hole in the intermediate base material with a drill tool;
With
In the drilling step, a vibration of the drill tool is detected, and a deviation amount of the hole is measured from the detected vibration.   2. The hole formation is interrupted in the drilling step, when the measured deviation amount of the hole exceeds a predetermined allowable range of the deviation amount of the hole. Manufacturing method of optical fiber preform.   In the drilling step, when the measured deviation amount of the hole exceeds a predetermined range within a predetermined allowable range of the deviation amount of the hole, the feed rate of the drill tool is reduced. The manufacturing method of the preform | base_material for optical fibers of Claim 1.   In the drilling step, when the measured deviation amount of the hole exceeds a predetermined range within a predetermined allowable range of the deviation amount of the hole, the number of rotations per unit time of the drill tool is increased. The method for producing a preform for an optical fiber according to claim 1, wherein:   In the drilling step, when the measured deviation amount of the hole exceeds a predetermined range within a predetermined allowable range of the deviation amount of the hole, the pressure of the cutting water introduced into the hole is changed. The optical fiber preform manufacturing method according to claim 1, wherein the optical fiber preform is raised.   In the drilling step, when the measured deviation amount of the hole exceeds a predetermined range within a predetermined allowable range of the deviation amount of the hole, dressing is performed on the drill tool. The manufacturing method of the preform for optical fibers according to claim 1.   In the drilling step, if the measured deviation amount of the hole exceeds a predetermined range within a predetermined allowable range of the deviation amount of the hole, the tip of the drill tool and the intermediate base material are The method for manufacturing an optical fiber preform according to claim 1, wherein a distance from an upper surface of the intermediate preform to a portion where the drill tool is chucked is shortened when contacting.   The vibration of the drill tool is detected by detecting the vibration of the intermediate base material by a vibration detection sensor attached to the intermediate base material. Manufacturing method of optical fiber preform.   8. The fiber according to claim 1, wherein the vibration of the drill tool is detected by detecting a deflection amount during rotation of the drill tool by a non-contact displacement sensor. 9. A manufacturing method of a base material.   The vibration of the drill tool is detected by detecting the vibration of the drilling device by a vibration detection sensor attached to the drilling device that rotates the drill tool. The manufacturing method of the preform | base_material for optical fibers as described in a term.   An optical fiber manufacturing method comprising a drawing step of drawing an optical fiber preform manufactured by the optical fiber preform manufacturing method according to claim 1.

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