JP2014123157A - Optical fiber discrimination method and optical fiber fusion splicing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical fiber discrimination method which is capable of accurately discriminating a type of an optical fiber even in the case that it is difficult to recognize brightness waveform features of the optical fiber, such as an optical fiber having a complicated refractive index distribution or an elliptic core optical fiber.SOLUTION: When end surfaces 1a and 3a of a pair of optical fibers 1 and 3 are fusion-spliced together, a type of the optical fibers is discriminated from picked-up images of the end surfaces of the optical fibers. Brightness patterns of the optical fiber end surfaces obtained by picking up images of the end surfaces of the optical fibers from the front by imaging means 25 and 27 disposed so as to face the end surface of the optical fibers are collated with basic brightness patterns preliminarily stored per type of optical fibers, and a basic brightness pattern matching the brightness patterns is obtained to discriminate the type of the optical fibers.

Description

  The present invention relates to an optical fiber discrimination method and an optical fiber fusion splicing method.

  For example, the distance between the bright part end of the luminance distribution obtained by imaging the end face of the optical fiber with a camera from the side and the brightness peak closest to the bright part end is obtained on both sides of the bright part end, and the sum of the distances is obtained. A technique is disclosed in which adjustment is performed so as to be minimized and the stress applying portions of both optical fibers are made to coincide with each other to be fusion spliced (for example, described in Patent Document 1).

JP 2002-328253 A

  However, in the technique described in Patent Document 1, since image processing is performed on a transmitted light image obtained by capturing the end face of the optical fiber from the side with a camera, an optical fiber having a complicated refractive index distribution or an elliptical core optical fiber is used. Thus, when it is difficult to grasp the characteristics of the luminance waveform, it is difficult to determine the type of the optical fiber.

  Therefore, the present invention provides an optical fiber discrimination method and an optical fiber that can accurately determine the type of an optical fiber even when it is difficult to grasp the characteristics of the luminance waveform, such as an optical fiber having a complicated refractive index distribution or an elliptical core optical fiber. An object of the present invention is to provide a fusion splicing method for fibers.

  According to a first aspect of the present invention, there is provided an optical fiber discrimination method for discriminating the type of an optical fiber from an image obtained by imaging the end faces of the optical fiber when the end faces of a pair of optical fibers are fused and connected. The luminance pattern of the end face of the optical fiber obtained by imaging the end face of the optical fiber from the front with the imaging means arranged in a face-to-face comparison with the basic brightness pattern stored in advance for each type of optical fiber, It is characterized in that the type of optical fiber is determined by obtaining a matching basic luminance pattern.

  The second invention is characterized in that, in the first invention, after the discharge to the end face of the optical fiber, the end face of the optical fiber is imaged by the imaging means.

  According to a third aspect of the invention, after the type of the optical fiber is determined by the optical fiber determination method of the first or second aspect of the invention, the optical fibers are rotated around the axis and aligned, and then the end faces of both optical fibers are aligned. An optical fiber fusion splicing method characterized by comprising:

  According to the optical fiber discrimination method of the present invention, since the luminance pattern of the optical fiber end surface obtained by imaging the end surface of the optical fiber from the front is used by the imaging means, the end surface of the optical fiber is imaged obliquely. Compared to the above, an accurate luminance pattern can be obtained. As a result, if an accurate luminance pattern is compared with a basic luminance pattern stored in advance for each type of optical fiber, a basic luminance pattern that matches the luminance pattern can be quickly and accurately obtained. Can be easily determined.

FIG. 1 is a perspective view of a fusion splicing device according to an embodiment of the present invention. FIG. 2 is a side view showing a portion for holding the optical fiber of the fusion splicing apparatus of FIG. FIG. 3 shows a state in which the end face of one optical fiber is imaged by the fusion splicing apparatus of FIG. 1, (a) is a plan view thereof, and (b) is a right side view of (a). 4A and 4B show a state in which the end face of the other optical fiber is imaged by the fusion splicer of FIG. 1, FIG. 4A is a plan view thereof, and FIG. 4B is a right side view of FIG. 5 shows a state in which the mirror shaft is at the rising end position in the fusion splicing device of FIG. 1, (a) is a side view seen from the side perpendicular to the optical fiber of FIG. 1, and (b) is a diagram. It is the front view seen from the length direction to 1 optical fiber. 6 shows a state where the mirror shaft is in the lowered end position in the fusion splicing apparatus of FIG. 1, (a) is a side view seen from the side perpendicular to the optical fiber of FIG. 1, and (b) is a diagram. It is the front view seen from the length direction to 1 optical fiber. FIG. 7 is a control block diagram of the fusion splicer of FIG. FIG. 8 is a view corresponding to FIG. 3 in the fusion splicing device according to another embodiment of the present invention, in which (a) is a plan view and (b) is a right side view of (a). FIG. 9 is a view corresponding to FIG. 4 in the fusion splicing device according to another embodiment of the present invention, in which (a) is a plan view and (b) is a right side view of (a). FIG. 10 shows a sample used for discriminating the type of optical fiber by the method of the present invention. (A) is a panda type optical fiber, (b) is a bow tie type optical fiber, and (c) is an elliptical jacket type optical fiber. It is a front view which shows an end surface shape. FIG. 11 is a flowchart for discriminating the type of optical fiber by the method of the present invention. FIG. 12 shows an example of a panda-type optical fiber, where (a) shows the end face image and (b) shows the luminance pattern. FIG. 13 shows an example of a bow-tie optical fiber, where (a) shows the end face image and (b) shows the luminance pattern. FIG. 14 shows an example of an elliptic jacket type, where (a) shows the end face image and (b) shows the luminance pattern.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings.

  Before describing the optical fiber discrimination method of the present invention, a fusion splicing device for fusion splicing the end faces of a pair of optical fibers will be described. As shown in FIG. 1, the pair of optical fibers 1 and 3 correspond to the optical fibers 1 and 3 in a state where the optical fibers 1 and 3 face each other in the axial direction and the end surfaces 1a and 3a are separated from each other. It is gripped by the provided fiber holder 5 shown in FIG. The fiber holder 5 is pressed with a pressing plate 11 that can be opened and closed from above while the optical fibers 1 and 3 are housed in the recesses of the holder main body 9 that is detachably mounted on the holder base 7. Fix it.

  As shown in FIG. 2, the optical fibers 1 and 3 are provided with coating resins 1B and 3B covering the outer circumferences of the quartz glass fibers 1A and 3A, and the portions provided with the coating resins 1B and 3B are connected to the fiber holder. 5 grips. In addition, the optical fibers 1 and 3 here use regular polarization optical fibers in addition to ordinary optical fibers.

  Further, the end faces 1 a and 3 a of the optical fibers 1 and 3 are positioned and held by the V groove bases 13 and 15 on the side of the optical fibers 1 and 3 with respect to the fiber holder 5 described above. Similarly to the fiber holder 5, the V-groove bases 13 and 15 are positioned and fixed to the portions provided with the coating resins 1B and 3B, but the glass fibers 1A and 3A may be positioned and fixed.

  The V-groove bases 13 and 15 are provided with clamps (not shown) that partially enter the V-grooves 13 a and 15 a and press the optical fibers 1 and 3 between the V-groove bases 13 and 15.

  The fiber holder 5 described above, after imaging and observing the end faces 1a and 3a of the pair of optical fibers 1 and 3 by a method described later, for alignment or axial alignment between the optical fibers 1 and 3, It is assumed that the whole rotates about the axis of the optical fibers 1 and 3.

  As shown in FIG. 1, LED lamps 17 and 19 that project light into the optical fibers 1 and 3 from the side are disposed at appropriate positions of the pair of optical fibers 1 and 3. Light projected into the optical fibers 1 and 3 by the LED lamps 17 and 19 is radiated from the end faces 1 a and 3 a of the optical fibers 1 and 3.

  The portions of the optical fibers 1 and 3 that project light by the LED lamps 17 and 19 may be the glass fibers 1A and 3A or the portions including the coating resins 1B and 3B, but the coating resin 1B. , 3B, the coating resins 1B, 3B need to be transparent. Moreover, it is necessary to cover an outer peripheral part with respect to the optical fiber 1 and 3 of the part which projects light with the LED lamps 17 and 19 so that the projected light may not leak outside.

  Further, in FIG. 1, the LED lamps 17 and 19 are arranged on the side portions of the optical fibers 1 and 3, but when the optical fibers 1 and 3 are short, the LED lamps start from the end surface opposite to the end surfaces 1a and 3a. May be projected.

  Between the end faces 1a and 3a of the pair of optical fibers 1 and 3, a mirror shaft 21 as a reflecting member extending in the vertical direction perpendicular to the axial direction of the optical fibers 1 and 3 can be moved up and down and rotated. It is arranged. A concave portion 21a is formed in one side portion near the tip (upper end) of the mirror shaft 21, and a mirror 23 constituting a reflecting surface is attached to the concave portion 21a.

  The mirror 23 reflects either one of the end faces 1a and 3a of the optical fibers 1 and 3 in a state where the mirror shaft 21 is positioned at the rising end as shown in FIG. The reflected light of the mirror 23 is directed to either one of the first television camera 25 as the first imaging means and the second television camera 27 as the second imaging means arranged on the side. The optical axes of the optical systems of the first and second television cameras 25 and 27 are arranged in an inclined state with respect to the horizontal plane, and are provided with first and second lenses 25a and 27a, respectively, on the front end side. .

  Here, as shown in FIG. 3 corresponding to the state of FIG. 1, in the first state, the image of the end face 1a of one optical fiber 1 is reflected by the mirror 23 and is incident on the first lens 25a. In the state where the mirror shaft 21 is rotated 180 degrees from the state of FIGS. 1 and 3, as shown in FIG. 4, the image of the end face 3 a of the other optical fiber 3 is reflected by the mirror 23 as the second state. The light is reflected and incident on the second lens 27a. Since the reflecting surface of the mirror 23 is positioned so as to include the rotation axis of the mirror shaft 21, the position of the reflecting surface does not change even if the mirror shaft 21 rotates 180 degrees.

  Next, a rotation mechanism that rotates about the rotation axis of the mirror shaft 21 orthogonal to the axis of the optical fibers 1 and 3 will be described. 5 shows a state in which the mirror shaft 21 is located at the rising end as in FIG. 1, FIG. 6 shows a state in which the mirror shaft 21 is located at the falling end, and the state of FIG. With respect to the state, the mirror shaft 21 is rotated 90 degrees clockwise around the rotation axis as viewed from above in FIG.

  The mirror shaft 21 can move up and down with respect to the fixed bracket 29, and the fixed bracket 29 includes a guide tube 31 having a lower portion attached so as to protrude upward from the upper plate portion 29 a. The mirror shaft 21 in the state of being inserted into the vertical movement moves up and down. A stopper flange 32 is attached to the mirror 23 on the tip side of the guide tube 31 of the mirror shaft 21, and when the mirror shaft 21 is lowered as shown in FIG. 6, the upper end of the guide tube 31 is connected to the stopper flange 32. It abuts and restricts further lowering of the mirror shaft 21.

  A cylindrical member 33 is provided at the lower end of the mirror shaft 21 so as to be integrated, and a groove 35 illustrated as a front view in FIG. 6A is formed in one of the semicircular arc portions of the outer peripheral portion of the cylindrical member 33. doing. The groove 35 includes a first inclined groove 35a that spirals from the vicinity of the end of the mirror shaft 21 opposite to the mirror 23 in the axial direction to the vicinity of the end of the mirror 23, and the upper end of the first inclined groove 35a. A second inclined groove 35b having a spiral shape downward from the mirror 23 is provided.

  Here, the surface on the mirror 23 side of the first inclined groove 35 a becomes the guide inclined surface 37. On the other hand, in the second inclined groove 35 b, the surface opposite to the mirror 23 becomes the guide inclined surface 39. Each of these guide inclined surfaces 37, 39 constitutes at least a pair of cam surfaces having different inclination directions and facing each other.

  Further, as shown in FIG. 5B, the guide inclined surfaces 37 and 39 are formed close to each other along the rotation direction, and the adjacent portions of the pair of guide inclined surfaces 37 and 39 are circumferential. Are overlapping each other. That is, as shown in FIG. 5B, the upper end 37a of the guide inclined surface 37 and the upper end 39a of the guide inclined surface 39 overlap each other in the rotational direction.

  Further, as shown in FIG. 5A, a lower axial groove 41 extending in the vertical direction is formed in the lower portion in the axial direction facing the guide inclined surface 37 in the cylindrical member 33, as shown in FIG. 5B. As described above, an upper axial groove 43 extending in the vertical direction is formed on the upper portion in the axial direction of the cylindrical member 33 facing the guide inclined surface 39. These axial grooves 41 and 43 are set at positions separated by an angle of 90 degrees in the circumferential direction.

  The fixed bracket 29 is provided with a protrusion 45 as a guided portion that moves relatively along the spiral groove 35 and the axial grooves 41 and 43. The projecting portion 45 protrudes inward at the tip of an arm portion 29b extending downward from one side portion of the upper plate portion 29a of the fixing bracket 29 so as to enter the groove 35 and the axial grooves 41 and 43. Forming. The protrusion 45 is located in the lower axial groove 41 in FIG. 5, and is located in the upper axial groove 43 in FIG. The rotation of 23 is restricted.

  The spiral groove 35 and the axial grooves 41 and 43 are similarly formed on the other semicircular arc portion of the outer peripheral portion of the cylindrical member 33, that is, on the back side of the paper surface in FIG.

  A spring 47 as an elastic means is provided between the upper end surface of the cylindrical member 33 provided with the groove 35 and the axial grooves 41 and 43 and the upper plate portion 29a of the fixing bracket 29. Therefore, the mirror shaft 21 is always pressed downward.

  As shown in FIGS. 5B and 6B, a mirror shaft drive mechanism mounting portion 49 is formed on the opposite side of the arm portion 29b with the mirror shaft 21 of the fixed bracket 29 interposed therebetween. Yes. The mirror shaft drive mechanism mounting portion 49 includes a motor mounting arm 51 that bends upward on the outer side opposite to the mirror shaft 21 and a rotation link mounting arm 53 that bends downward on the outer side opposite to the mirror shaft 21. ing.

  A motor 55 as drive means is attached to the upper part of the motor attachment arm 51, and a rotation link 59 is rotatably attached to the tip of the rotation link attachment arm 53 via a rotation support pin 57. The rotation drive shaft 61 of the motor 55 is connected to a screw shaft 63 of a ball screw. The rotation of the screw shaft 63 accompanying the rotation of the rotation drive shaft 61 causes the screw shaft 63 to rotate while rotating relative to a nut (not shown). Move in the direction.

  The tip of the screw shaft 63 is in contact with one end 59 a of the rotation link 59, and the other end 59 b of the rotation link 59 is in contact with the lower end surface of the cylindrical member 33.

  In the state where the mirror shaft 21 is located at the rising end as shown in FIGS. 1 and 5, the screw shaft 63 is moving forward, and at this time, the other end portion 59 b of the rotation link 59 is located on the lower end surface of the cylindrical member 33. By pressing upward, the spring 47 is in a compressed state. From this state, when the motor 55 is driven to move the screw shaft 63 backward, the rotation link 59 rotates counterclockwise in FIG. 5B, and the spring 47 is extended accordingly. Due to the elastic force of the spring 47, the cylindrical member 33 is lowered together with the mirror shaft 21 as shown in FIG.

  When the cylindrical member 33 moves downward from the state of FIG. 5, the projection 45 moves relatively upward from the lower axial groove 41 and comes into contact with the guide inclined surface 37 immediately above the protrusion 45. Will move relative to the guide inclined surface 37 while being pressed against it. Here, since the protrusion 45 is provided on the fixing bracket 29 and is fixed, the cylindrical member 33 is rotated clockwise as viewed from above in FIG. Is rotated 90 degrees to the state shown in FIG. That is, the mirror shaft 21 is located at the descending end, and at this time, the protrusion 45 is in a state of entering the upper axial groove 43 and the spring 47 is in an extended state.

  Subsequently, from the state of FIG. 6, when the motor 55 is rotationally driven in the opposite direction to move the screw shaft 63 to advance, the rotation link 59 rotates clockwise in FIG. The cylindrical member 33 is raised against the spring 47. When the cylindrical member 33 is lifted, the projection 45 located in the upper axial groove 43 as shown in FIG. 6A comes into contact with and is pressed against the guide inclined surface 39 immediately below the cylindrical member 33. The shape member 33 further rotates 90 degrees in the same direction as described above.

  As described above, the mirror shaft 21 is lowered from the state where the mirror shaft 21 is located at the rising end position of FIGS. 1 and 5 by rotating the screw shaft 63 by driving the motor 55 and moving backward by 90 degrees. Moves forward by 90 degrees in the same direction. Thus, by repeating the backward movement and forward movement of the screw shaft 63 once, the mirror shaft 21 can be in a state in which the direction of the mirror 23 is rotated 180 degrees at the rising end position.

  That is, in the state of FIGS. 1 and 5, the image of the end face 1 a of one optical fiber 1 is reflected by the mirror 23 and incident on the first lens 25 a and can be picked up by the first television camera 25. . From this state, the mirror shaft 21 is rotated 180 degrees by driving the motor 55 as described above, so that the image of the end face 3a of the other optical fiber 3 is reflected by the mirror 23 and enters the second lens 27a. The second television camera 27 can take an image.

  After the mirror shaft 21 is rotated 180 degrees, the screw 55 is further driven backward and forward once by driving the motor 55 so that the orientation of the mirror 23 is the original state, that is, one of the optical fibers 1 in FIG. It returns to the state which reflects the image of the end surface 1a.

  As shown in FIG. 7, the images taken by the first and second television cameras 25 and 27 are individually image-processed by the image processing circuit of the control unit 65 to obtain different data, and based on these data. Then, the entire fiber holder 5 shown in FIG. 2 is rotated around the axis of the optical fibers 1 and 3 to perform alignment work. Alternatively, only the V-groove bases 13 and 15 are moved in the radial direction to perform axial alignment. Separate image data of the optical fibers 1 and 3 are individually displayed on the first display unit 69 and the second display unit 70.

  After the alignment operation and the axial alignment, the end faces 1a and 3a of the optical fibers 1 and 3 are brought into contact with each other and fusion-bonded using a discharge electrode (not shown). At the time of fusion splicing, the mirror shaft 21 is positioned at the lower end as shown in FIG. 6 so that the mirror shaft 21 does not get in the way. When the end faces 1a and 3a are brought into contact with each other, the fiber holder 5 is moved in the axial direction.

  As described above, in the present embodiment, when imaging the end faces 1a and 3a of the pair of optical fibers 1 and 3 to be fusion-spliced, the single mirror 23 provided on the mirror shaft 21 rotated by 180 degrees is used. Images are individually acquired from the front of the end faces 1a and 3a of the optical fibers 1 and 3, respectively. For this reason, it is possible to acquire a high-accuracy image by imaging the end faces 1a and 3a from the front as compared with the case where the optical fiber is taken from the side, and to each end face 1a and 3a of the pair of optical fibers 1 and 3 High-accuracy images can be acquired by individually capturing images with the corresponding first TV camera 25 and second TV camera 27.

  At this time, since the first television camera 25 captures an image of the end face 1a of one optical fiber 1, the image can be received at the center of the first lens 25a, and the second television camera 27 can receive the other image. Since the image of the end face 3a of the optical fiber 3 is taken, the image can be received at the center of the second lens 27a. As a result, even when the fiber diameter is large, it is easy to fit within the imaging range of the TV camera, resulting in an incomplete image as if both of the pair of optical fibers were simultaneously imaged by one TV camera. This can be avoided and a highly accurate image can be obtained.

  In addition, by imaging and observing the end faces 1a and 3a of the optical fibers 1 and 3, it is possible to find damaged parts such as chips on the end faces 1a and 3a. You can also

  Moreover, in this embodiment, the mirror axis | shaft 21 is equipped with one mirror 23, and it is 180 degree | times centering on the rotating axis orthogonal to the axis line of the optical fibers 1 and 3 between a 1st state and a 2nd state. A first television camera 25 that can rotate and captures an image of one end face 1a reflected in the first state, and a second television image that captures an image of the other end face 3a reflected in the second state. And a television camera 27.

  Thereby, the image of each end surface 1a, 3a can be individually reflected toward the 1st, 2nd television cameras 25, 27 using one mirror 23, These 1st, 2nd televisions It is possible to easily specify whether the image captured by the cameras 25 and 27 is one of the pair of optical fibers 1 and 3.

  In the present embodiment, the guide inclined surfaces 37 and 39 are provided on the mirror shaft 21 and are inclined in a spiral shape facing the axial direction of the rotation axis and turning around the rotation axis, A projection 45 that moves relative to the inclined surfaces 37 and 39 while being guided with respect to the surface 39 and moves the mirror shaft 21 in the axial direction of the rotational axis, and at the same time, rotates about the axis of the rotational axis. , Respectively. The guide inclined surfaces 37 and 39 are formed such that at least a pair of guide inclined surfaces 37 and 39 having different shapes and facing each other are adjacent to each other along the rotation direction. , 39 are adjacent to each other in the circumferential direction.

  As a result, the mirror shaft 21 reciprocates in the vertical direction, so that the protrusion 45 is sequentially guided by the guide inclined surfaces 37 and 39, and the mirror shaft 21 is rotated by 90 degrees in the same direction and rotated 180 degrees. Is possible.

  In the present embodiment, the mirror shaft 21 moves in one axial direction of the rotation axis, so that one of the pair of guide inclined surfaces 37 and 39 moves while contacting the protrusion 45 and rotates 90 degrees. Then, by moving to the other axial direction of the rotation axis, the other of the pair of guide inclined surfaces 37 and 39 moves while contacting the protrusion 45 and rotates 90 degrees.

  For this reason, it is possible to rotate the mirror shaft 21 by 90 degrees in the same direction and to rotate 180 degrees simply by moving up and down.

  In the present embodiment, a spring 47 that moves the mirror shaft 21 in one axial direction of the rotation axis, and a motor 55 that moves the mirror shaft 21 in the other axial direction of the rotation axis against the spring 47, It has. Therefore, the mirror shaft 21 moves to one side by driving the motor 55 against the spring 47, and conversely, the mirror 47 is easily driven to the other side by releasing the drive of the motor 55 in the compression direction to the spring 47. Can be moved to. At this time, since only one motor 55 is required, the number of parts can be reduced and the structure can be simplified.

  Furthermore, in the present embodiment, a first display unit 69 and a first display unit 70 that display the respective images captured by the first TV camera 25 and the second TV camera 27 are provided. The respective images are individually displayed by the display units 69 and 70. Thereby, observation of each end face 1a and 3a of a pair of optical fibers 1 and 3 can be performed very easily.

  In the above-described embodiment, the two first and second television cameras 25 and 27 are provided as the imaging unit. However, the mirror shaft 23 is rotated 90 degrees counterclockwise from the state of FIG. Thus, the reflected light of the images of the end faces 1a and 3a is set in the same direction (downward in FIG. 3 (a)), so that even one television camera can be used. However, in this case, the mirror shaft 23 needs to have a structure that does not move up and down when rotating, and a drive mechanism that only rotates and a drive mechanism that only moves up and down to retreat downward during fusion are required. It becomes.

  In the above-described embodiment, only one protrusion 45 is provided at the lower end of the arm 29b. However, the protrusion 45 is provided at the lower end of the mirror shaft drive mechanism mounting portion 49 at a position facing the protrusion 45. 5 may be provided symmetrically with the protrusion 45 in FIG. 5B. Similar to the protrusion 45, this other protrusion also moves relative to the groove 35 and performs the same function as the protrusion 45.

  Further, the other protrusion may be provided at a different position in the axial direction with respect to the protrusion 45, and a groove similar to the groove 35 may be provided at a different position in the axial direction.

  In other embodiments shown in FIGS. 8 and 9, two mirrors 23 </ b> A and 23 </ b> B are provided on the mirror shaft 210 in a state of being separated from each other along the axial direction. The mirror shaft 210 is movable in the axial direction orthogonal to the paper surface in FIGS. 8A and 9A, and the two mirrors 23A and 23B are positioned 180 degrees around the axis of the mirror shaft 210. Is different. Therefore, by moving the mirror 10 in the axial direction, one of the two mirrors 23A and 23B can be positioned on the axis of the optical fibers 1 and 3.

  FIG. 8 shows a state in which the mirror shaft 210 is raised. In this state, the mirror 23A located on the base side is located on the axis of the optical fibers 1 and 3, and the mirror 23A is in the first state at this time. The image of the end face 1a of one optical fiber 1 is reflected and incident on the first lens 25a of the first television camera 25.

  On the other hand, FIG. 9 shows a state in which the mirror shaft 210 is lowered. In this state, the mirror 23B located on the tip side is located on the axis of the optical fibers 1 and 3, and at this time, the mirror 23B As a state, the image of the end face 3 a of the other optical fiber 3 is reflected and incident on the second lens 27 a of the second television camera 27.

  As described above, also in the present embodiment, the end faces 1a and 3a of the pair of optical fibers 1 and 3 can be individually imaged and observed from the front, so that it is higher than when the optical fiber is imaged from the side. An accurate image can be acquired, and a high-accuracy image can be acquired by the first television camera 25 and the second television camera 27 corresponding to the end faces 1a and 3a of the pair of optical fibers 1 and 3, respectively.

  In this embodiment, the two mirrors 23A and 23B are used. However, the mirror shaft 210 to which these mirrors 23A and 23B are attached is moved only in the axial direction of the pair of optical fibers 1 and 3. One of the end faces 1a and 3a can be imaged from the front, and the overall structure can be simplified as compared with the above-described embodiment provided with a mechanism for rotating the mirror shaft.

  Also in this embodiment, by providing a mechanism for rotating the mirror shaft 210, for example, from the state of FIG. 8, the mirror shaft 210 is lowered and rotated 90 degrees clockwise in FIG. 8A. In FIG. 8 and FIG. 9, one of the lower television cameras 25 may be used.

  Next, when the end faces 1a and 3a of the optical fibers 1 and 3 are fused and connected by the fusion splicing apparatus described above, the end faces 1a and 3a of the optical fibers 1 and 3 are connected to the first television camera 25 and the second An optical fiber discrimination method for discriminating the types of optical fibers 1 and 3 from an image obtained by imaging with the television camera 27 will be described.

  As the optical fibers 1 and 3, there are constant polarization optical fibers which are equivalently birefringent by applying different stresses from two directions orthogonal to the core portion. As shown in FIG. 10, the constant polarization optical fiber has a structure in which stress applying portions 101 and 101 are provided on both sides of the core 100, for example. The constant polarization optical fiber has, for example, a panda type optical fiber 1 (3) shown in FIG. 10A, a bow tie type optical fiber 1 (3) shown in FIG. 10B, and an ellipse shown in FIG. There is what is called a jacket type optical fiber 1 (3). In order to fusion splice this constant polarization optical fiber, it is necessary to match the planes of polarization with each other. Therefore, it is necessary to determine which type of optical fiber the cross-sectional shape of the optical fiber 1 (3) is. is there. The types of the optical fibers 1 and 3 are not limited to constant polarization optical fibers but may be ordinary optical fibers.

  In this embodiment, before the fusion splicing device is used for fusion splicing, the types of the optical fibers 1 and 3 are determined as follows. FIG. 11 shows a flowchart for determining the type of optical fiber. First, in the process of step S1, discharge is generated by applying a voltage between discharge electrodes (not shown) provided in the above-described fusion splicer. And it discharges to the end surfaces 1a and 3a of both optical fibers 1 and 3. Since the end faces 1a and 3a of the optical fibers 1 and 3 are melted differently in places where the additive is present and where the additive is not present due to discharge, the end faces 1a and 3a are uneven, and the stress applying portions 101 and 101 are emphasized. The This makes it easy to observe features such as the refractive index distribution from the images of the end faces 1a and 3a of the optical fibers 1 and 3.

  Next, in the process of step S2, the image of the end surface 1a is picked up by the first television camera 25 with the direction of the mirror 23 facing the end surface 1a of one optical fiber 1, and the direction of the mirror 23 is changed to the other in the same manner. The second television camera 27 takes an image of the end face 3a toward the end face 3a of the optical fiber 3. Then, the images of both optical fibers 1 and 3 are displayed on the first and second display sections 69 and 70, respectively. FIG. 12A shows an image of the optical fiber 1 (3) displayed on the display units 69 and 70. Here, an image of the panda type optical fiber 1 is displayed.

  Then, by processing the image data obtained by imaging the end faces 1a and 3a of the panda type optical fibers 1 and 3, a luminance pattern as shown in FIG. 12B is created. The luminance pattern in FIG. 12A indicates the luminance on a straight line X connecting the core portion 100 of the optical fiber 1 (3) and the centers of the stress applying portions 101 and 101 provided on both sides thereof. In this figure, the luminance A of the portion corresponding to the stress applying portions 101 and 101 and the luminance B of the portion corresponding to the core portion 100 are both the same luminance and lower than the luminance of the other portions.

  Next, in the process of step S3, the luminance pattern (luminance pattern shown in FIG. 12B) of the optical fiber end surface obtained by imaging the end surface 1a (3a) of the optical fiber 1 (3) from the front is previously stored. The basic luminance pattern stored for each type of optical fiber is collated. In this embodiment, three types of luminance patterns of a panda type optical fiber, a bow tie type optical fiber, and an elliptical jacket type optical fiber are stored in advance in the storage means as basic luminance patterns. Of course, the luminance pattern in optical fibers other than these three types of optical fibers can also be stored in the storage means as a basic luminance pattern.

  Then, the actually obtained luminance pattern of FIG. 12B is collated with the basic luminance pattern stored in the storage means. Next, in step S4, a basic luminance pattern that matches the luminance pattern is obtained, and the type of the optical fiber 1 (3) is determined from the basic luminance pattern.

  FIG. 12 shows an example of a panda type optical fiber. FIG. 13 shows an example of a bow tie type optical fiber, and FIG. 14 shows an example of an elliptical jacket type optical fiber. As shown in FIG. 13A, the image of the bow tie optical fiber 1 (3) displayed on the display units 69 and 70 is a core unit 100 and a stress applying unit 101 having a substantially rectangular shape provided on both sides thereof. , 101 is displayed smaller than the other parts. The brightness pattern of the bow tie type optical fiber 1 (3) corresponds to the stress applying portions 101 and 101 with respect to the brightness pattern of the panda type optical fiber 1 (3) as shown in FIG. The brightness range of is small.

  In the image of the elliptical jacket type optical fiber 1 (3) displayed on the display units 69 and 70, only the luminance of the elliptical core unit 100 is displayed as shown in FIG. And the luminance pattern of this elliptical jacket type optical fiber 1 (3) does not have the stress applying part 101 unlike the panda type optical fiber and the bow tie type optical fiber, as shown in FIG.

  Thus, the luminance pattern of the optical fiber end face obtained by imaging the end faces 1a and 3a of the optical fibers 1 and 3 from the front is collated with the basic luminance pattern stored in advance for each type of the optical fibers 1 and 3. The types of the optical fibers 1 and 3 are determined by obtaining a basic luminance pattern that matches the luminance pattern. As in the present invention, since the end faces 1a and 3a of the optical fibers 1 and 3 are imaged from the front rather than obliquely, an accurate luminance pattern can be obtained. Therefore, even when the characteristics of the luminance pattern are difficult to grasp, such as an optical fiber having a complicated refractive index distribution or an elliptical jacket type optical fiber, it is possible to easily determine the type of the optical fiber.

  Further, in the present invention, since the optical fiber end face is imaged by the imaging means after discharging to the end faces of the optical fibers 1 and 3, the end face 1a is different depending on how the additive is present and not present. , 3a is uneven, and the stress applying portion 101 is emphasized. Thereby, the luminance pattern of the end face of the optical fiber imaged by the imaging means can be obtained accurately.

  When the types of the optical fibers 1 and 3 are determined as described above, the two optical fibers 1 and 3 are fused and connected. For example, in the case of a constant polarization optical fiber, the optical fibers 1 and 3 are aligned by rotating the optical fibers 1 and 3 about the axis so that the polarization planes of both the optical fibers 1 and 3 coincide. Thereafter, the end faces of both optical fibers 1 and 3 are fused and connected. In the optical fibers 1 and 3 thus fused and connected, the optical fibers 1 and 3 are connected in a state in which the polarization planes of both the optical fibers 1 and 3 are accurately matched, so that an optical fiber cable with little transmission loss can be obtained.

  The present invention can be used to determine the type of an optical fiber by using a luminance pattern obtained from an image obtained by imaging the end face of the optical fiber.

1, 3 ... Optical fiber 23 ... Mirror (imaging means)
25, 27 ... TV camera (imaging means)
DESCRIPTION OF SYMBOLS 100 ... Core part 101 ... Stress application part

Claims (5)

In the optical fiber discriminating method for discriminating the type of the optical fiber from the image obtained by imaging the end face of the optical fiber when the end faces of the pair of optical fibers having the polarization planes are fusion-spliced,
The type of optical fiber is determined while specifying the plane of polarization based only on the image obtained by imaging the end face of the optical fiber from the front with a specific one rotation angle around the axis of the optical fiber by the imaging means. Fiber identification method. The optical fiber discrimination method according to claim 1,
The optical fiber may have a core portion and further a stress applying portion,
An optical fiber discriminating method for discriminating a type of an optical fiber while identifying a polarization plane based on a characteristic relating to the stress applying portion obtained on a straight line passing through the core portion in the image obtained by imaging with the imaging means. An optical fiber discrimination method according to claim 2,
The feature relating to the stress applying portion includes at least a range of the stress applying portion obtained on a straight line passing through the core portion in the image obtained by imaging with the imaging means. An optical fiber discrimination method according to any one of claims 1 to 3,
An optical fiber discriminating method for imaging an optical fiber end face with the imaging means after discharging to the end face of the optical fiber. After discriminating the type of the optical fiber by the optical fiber discriminating method according to any one of claims 1 to 4, after rotating the optical fiber in the direction of the axis and aligning, the end faces of both optical fibers are aligned with each other. Fusion splicing method for optical fibers.

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