JP3816226B2 - Optical fiber preform inspection equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for measuring and measuring dimensions such as the length and outer diameter of an optical fiber preform.
[0002]
[Prior art]
The optical fiber preform is a transparent glass body before spinning having a core portion and a cladding portion, and its length, outer diameter, etc. are measured in preparation for the next spinning step and the like. The measurement items include the outer diameter, the total length, the effective length, the upper dummy length, and the like as the base material dimensions. In addition, there are a bent state, a weight, a mixed state of bubbles, and the like.
[0003]
Conventionally, these inspection items have been measured by a worker using a measuring instrument with the optical fiber preform lying sideways. For example, the total length, effective length, upper dummy length, etc. were measured with a measure, and the outer diameter was measured with calipers.
[0004]
[Problems to be solved by the invention]
However, as in the past, measuring each measurement item with each measuring instrument is not only inefficient, but there is also a risk of breaking the optical fiber preform. In other words, the optical fiber preform is made of glass that is easily broken, and has a weight, and handling it horizontally or vertically itself has a risk of cracking. Therefore, the handling is not easy and the efficiency is lowered.
[0005]
SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide an optical fiber preform inspection apparatus that can efficiently inspect each measurement item in a batch and that is less likely to break the optical fiber preform. .
[0006]
[Means for Solving the Problems]
In order to achieve the above object, in the optical fiber preform inspection apparatus according to the present invention, a gripping tool for gripping the upper end of the optical fiber preform, and supporting the suspension by hanging the gripping tool via a weighing device. A rotation support device that rotates about an axis, a light source that makes light incident from an open lower end of an optical fiber preform gripped by a gripper, an imaging device that captures an image from a side surface of the optical fiber preform, An image monitor device that receives an image signal picked up by the image pickup device and displays the image, an outer diameter measuring device that measures the outer diameter of the optical fiber, and light that is suspended from the image pickup device and the outer diameter measuring device And a moving device that moves up and down along the fiber preform.
[0007]
Since the outer shape measuring instrument is moved up and down along the suspended optical fiber preform, the outer diameter of each part can be measured, and since this optical fiber preform is rotated, the fluctuation of the measured outer diameter associated with the rotation can be measured. Can also bend the optical fiber preform. Since the optical fiber is suspended through the weighing device, its weight can be measured. Light enters from one end (lower end) of the suspended optical fiber preform, and light leaking from the side surface at each position in the length direction is captured by the imaging device and the image monitor device. Bubbles generated in the cladding can be detected. Therefore, the upper dummy length can also be measured. Since the core / cladding outer diameter ratio is obtained by measuring the outer diameter, the effective portion can be determined based on the core / cladding outer diameter ratio, and the effective length can be measured. In this way, by hanging the optical fiber preform from above, all measurement items can be measured at once, and since this is done with the optical fiber preform kept vertical from beginning to end, handling is easy and there is a risk of cracking. There are few.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings. In the optical fiber preform inspection apparatus shown in FIG. 1, the upper end of the optical fiber preform 10 is held by the chuck 23 and is suspended in the vertical direction. The optical fiber preform 10 basically includes a central core portion 11 and a clad portion 12 formed around the core portion 11 (both of which are made of transparent glass). For this purpose, glass rod dummy bars 13 and 14 are joined to both ends thereof. Therefore, the chuck 23 specifically holds the upper dummy bar 13.
[0009]
The chuck 23 is held by a rotation support device 21 via a load cell (weighing device for weighing), and the rotation support device 21 rotates the load cell 22 around a vertical rotation axis. The lower end of the optical fiber preform 10 is in an open state as a result of being gripped and suspended by the upper end, and therefore light is incident from the opened lower end (specifically, the lower end of the lower dummy bar 14). The light source 24 for the light incidence is arranged. The light source 24 is composed of, for example, a searchlight or a halogen lamp.
[0010]
The optical fiber preform 10 is sandwiched between the light projector 41 and the light receiver 42 of the laser outer diameter measuring device 40 on the side surface, and an image of the side surface is captured by the TV camera 43. Yes. The laser outer diameter measuring device 40 (light projector 41, light receiver 42) and the TV camera 43 are mounted on the moving frame 34 of the moving device 30, and the length direction (vertical direction) along the optical fiber preform 10. Can be moved to.
[0011]
In this moving device 30, a pole screw 32 arranged in the vertical direction is rotated by a motor 31, and when the pole screw 32 rotates, a nut portion 33 screwed together moves in the length direction of the pole screw 32. . Thereby, the moving frame 34 is moved in the vertical direction. Therefore, as the moving frame 34 moves, the measurement position of the laser outer diameter measuring instrument 40 and the imaging position by the TV camera 43 move in the length direction of the optical fiber preform 10, and the length Measurement of the outer diameter of each direction part and imaging of a side image are performed.
[0012]
In the laser outer diameter measuring device 40, a parallel laser beam is irradiated from the projector 41 toward the optical fiber preform 10, and is incident on a light receiver 42 disposed opposite to the optical fiber preform 10. Since the laser beam partially blocked by the optical fiber preform 10 is incident on the light receiver 42, the light beam is received by a one-dimensional CCD image sensor or the like, and the length of the shadowed portion is detected. The outer diameter is obtained, and the bend is obtained from the edge position of the shadow.
[0013]
The outer diameter measurement signal and the edge position signal are taken into the computer 50. An image signal from the TV camera 43 is also sent to the computer 50, and this image (side view image of the optical fiber preform 10) is displayed on the image monitor device 51. Further, a detection signal of the load cell 22, that is, a signal indicating the detected weight is also input to the computer 50. The computer 50 gives commands to the rotation support device 21 and the moving device 30 to control the rotation of the optical fiber preform 10 and the movement of the moving frame 34, that is, the measurement positions of the laser outer diameter measuring device 40 and the TV camera 43. Further, the rotation of the motor 31 (specifically, the pole screw 32) of the moving device 30 is counted by the computer 50, and the position (vertical direction) of the moving frame 34 is detected.
[0014]
Therefore, when the optical fiber preform 10 is to be inspected, the optical fiber preform 10 is first gripped by the chuck 23. Then, the weight is measured by the load cell 22 and the measurement signal is taken into the computer 50.
[0015]
Next, a command is given to the rotation support 21 to rotate the optical fiber preform 10 at an arbitrary speed, and a command is given to the moving device 30 to gradually move the moving frame 34 from the lowermost position to the uppermost position. Raise. Thus, the outer diameter is measured and the image is taken from the side while moving upward from the lowermost end of the rotating optical fiber preform 10.
[0016]
At this time, since the light from the light source 24 is incident on the optical fiber preform 10 from the lower end thereof, the upper and lower ends and the upper end of the optical fiber preform 10 are observed by observing an image taken from the side surface captured by the TV camera 43. The joint part between the lower dummy bars 13 and 14 and the main body part can be identified. Since the position of the moving frame 34, that is, the TV camera 43 is input to the computer 50, the positions of the upper and lower ends of the optical fiber preform 10 and the connection portions with the dummy bars 13 and 14 are taken into the computer 50. Thereby, the total length (the length between the upper and lower ends) and the length of the upper dummy bar 13 can be measured.
[0017]
Furthermore, since light entering the core portion 11 from the lower end and propagating through the core portion 11 leaks to the cladding portion 12, bubbles generated in the cladding portion 12 and the like can be observed with an image taken from the side imaged by the TV camera 43. . Thereby, the number and size of bubbles can be measured. With respect to the position of the bubbles, the position in the length direction and the circumferential direction of the optical fiber preform 10 can be known from the vertical position of the moving frame 34 and the rotation position of the rotation support 21. Are captured and recorded in the computer 50. When the image is taken by the TV camera 43, not only the optical fiber preform 10 to be inspected but also the entire inspection apparatus is covered with an appropriate cover so that it is darkened so that an image easy to observe can be taken. It is desirable to do.
[0018]
Since the outer diameter measuring device 40 scans the optical fiber preform 10 upward from the lower end, the outer diameter of the optical fiber preform 10 at each position in the length direction (the outer diameter of the cladding portion 12) is Will be measured. Since the glass particles cannot be deposited sufficiently at the upper and lower ends, the amount of deposition is small, the taper is formed and the clad portion 12 is thin, and the thinned portion cannot effectively spin the optical fiber. Although it does not become an effective part, by measuring the part where the clad part 12 is not less than a predetermined thickness with the outer diameter measuring instrument 40, it is possible to measure from where to where is the effective part (effective length).
[0019]
Then, the maximum value, minimum value, average value, and information on fluctuations in the outer diameter of the effective portion can be acquired. Further, since the optical fiber preform 10 is rotated, the position of the edge captured by the outer diameter measuring instrument 40 is shaken, and how much the shake is at any position in the length direction of the optical fiber preform 10. Therefore, it is possible to detect a bend.
[0020]
In addition, the above is related to one embodiment, and it is needless to say that the present invention is not limited to these descriptions. The specific configuration can be variously changed. For example, as the mechanism for moving the outer diameter measuring instrument 40 and the TV camera 43 up and down, a mechanism other than the screw / nut mechanism as described above can be used.
[0021]
【The invention's effect】
As described above, according to the optical fiber preform inspection apparatus of the present invention, all the inspection items such as the outer diameter, the total length, the effective length, the upper dummy length, the bend, the weight, and the mixed state of bubbles are measured at once. In addition, since the optical fiber preform is set while standing in the vertical direction, handling is easy and there is no risk of cracking, and inspection efficiency is increased.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram showing an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Optical fiber base material 11 Core part 12 Cladding part 13 Upper dummy stick 14 Lower dummy stick 21 Rotation supporter 22 Load cell 23 Chuck 24 Light source 30 Moving device 31 Motor 32 Pole screw 33 Nut part 34 Moving frame 40 Laser outer diameter measuring instrument 41 Projector 42 Photoreceiver 43 TV Camera 50 Computer 51 Image Monitor Device

Claims (1)

A gripping tool that grips the upper end of the optical fiber preform, a rotation support device that suspends and supports the gripping tool via a weighing device, and rotates around a vertical rotation axis, and an optical fiber preform that is gripped by the gripping tool A light source that allows light to enter from an open lower end of the optical fiber, an imaging device that captures an image from the side surface of the optical fiber preform, and an image monitor device that receives the image signal captured by the imaging device and displays the image And an outer diameter measuring device for measuring the outer diameter of the optical fiber, and a moving device for moving the imaging device and the outer diameter measuring device up and down along a suspended optical fiber preform. Fiber preform inspection equipment.

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