JP3222777B2 - Optical fiber preform shape measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the shape of an optical fiber preform.

[0002]

2. Description of the Related Art An optical fiber preform is a raw material base material for drawing an optical fiber and generally has an outer diameter of 3 mm.
It has a cylindrical shape with a length of about 0 to 60 mm and a length of about 1000 mm. The preform is heated to a high temperature of 2,000 ° C. or higher in a drawing furnace, and is drawn from below by a drawing device to 100 to 60 ° C.
It is processed into an optical fiber by drawing at a speed of 0 m / min.

[0003] If the preform has a large variation in outside diameter or a large amount of bending, a part of the preform may approach or come into contact with the wall of the furnace when the preform is installed in a drawing furnace. Then, since a part of the preform is locally heated, the cross section of the optical fiber obtained by drawing may not be circular, or the fiber may be broken during drawing. For this reason, before drawing, it is necessary to measure the shape of the preform and inspect whether the variation in outer diameter and the amount of bending are below the reference.

In a conventional preform shape measuring apparatus, two points at both ends of the preform are supported by a support made of Teflon, and a displacement meter, for example, a linear gauge counter made by Mitutoyo, model number LG-S1, is placed under the preform. It was arranged, the bending amount was measured while rotating the preform by hand every time the measurement was performed, the outer diameter was measured with calipers, etc., and the position of the displacement meter was moved each time those measurements were completed .

[0005]

As described above, in the conventional shape measuring device, manual work is required for each measurement.
Not only is the measurement operation complicated, but when measuring 100 points of the preform with a length of 1000 mm at 10 mm intervals, 1
It takes more than 5 minutes and takes too much time. Also, when measuring the outer diameter with a vernier caliper, the caliper must be brought into contact with the preform, so that the surface of the preform must not be scratched, which is a difficult task.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and does not damage the surface of the preform. It is an object of the present invention to provide a device capable of measuring the temperature.

[0007]

The optical fiber preform shape measuring apparatus of the present invention, which has been made in order to achieve the above object, has an optical fiber preform 1 provided on an optical fiber preform 1 as shown in FIG. Preform 1 by injecting light from the side
In the shape measuring apparatus for measuring the shape of the preform 1, the holding table 11 on which the preform 1 is mounted, and the preform 1 , in which the outgoing light is orthogonal to the direction perpendicular to the axial direction,
An outer diameter measuring device 2 for irradiating light with two laser irradiators 5 to measure the outer diameter, a driving means 4 for moving the outer diameter measuring device 2 in the longitudinal direction of the preform 1, and an outer diameter measuring device And a position detector 3 for detecting a measurement position of the device 2.

The outer diameter measuring device 2 has at least two laser irradiators 5, and it is preferable that the light emitted from each of the laser irradiators 5 is orthogonal to each other, and can simultaneously measure the diameter of the preform from two directions.

The holding table 11 is preferably made of polytetrafluoroethylene , so that the preform 1 is not damaged and can easily slide on the holding table 11.

The shape measuring device preferably has an automatic transfer device for transferring the optical fiber preform 1 to the holding table 11, so that the entire process of shape measurement can be performed almost unattended.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail.

FIG. 1 is a perspective view showing an embodiment of an apparatus for measuring the shape of an optical fiber preform according to the present invention. As shown in the drawing, the outer diameter measuring device 2 has two sets of laser irradiators 5 and laser receivers 6 (KL15X series manufactured by Anritsu Corporation), and each laser irradiator 5 emits a laser beam. The lights are arranged at orthogonal positions. The optical fiber preform 1 is a 10 mm thick Teflon holding base 11.
And placed at a position where the laser beams emitted from the two laser irradiators 5 of the outer diameter measuring device 2 intersect.
The outer diameter measuring device 2 is a preform 1 in two directions orthogonal at the same time.
The outer diameter of can be measured. The outer diameter measuring device 2 is attached to the scanning plate 7, and a ball nut 16 attached to the lower surface of the scanning plate 7 is screwed to a screw bar 13 attached to a fixed base 15 in parallel with the preform 1. The screw rod 13 is connected to the motor 4. Guide rail 1 on fixed base 15
The scanning plate 7 is slidably supported. Further, on the fixed base 15, a lure encoder 3 (GB / SR-108 series manufactured by Sony Magnescale Co., Ltd.) for detecting the measurement position of the outer diameter measuring device 2 with the detection window 8 is attached in parallel with the preform 1. Have been.

FIG. 2 is a control block diagram of the optical fiber preform shape measuring apparatus of the present invention. As shown in the figure, the linear encoder 3, the outer diameter measuring device 2, and the motor 4
The control circuit 10 is connected via a linear encoder operation unit 25, an outer diameter measuring unit operation unit 26, and a motor controller 21 respectively.
And its operation is controlled. The control circuit 10
It is connected to a data storage 22 of a hard disk for recording the calculation results.

The apparatus for measuring the shape of an optical fiber preform operates as follows.

First, an interval for measuring the shape of the optical fiber preform 1 is set in the control circuit 10 shown in FIG. 2, and the measurement is started. Then, as shown in FIG. 1, the motor 4 is driven intermittently, the outer diameter measuring device 2 repeatedly moves and stops in the direction of the arrow, and the orthogonality of the preform 1 measured when the outer diameter measuring device 2 stops. The outer diameter data in the direction and the measurement position data detected by the linear encoder 3 are processed by the linear encoder calculator 25 and the outer diameter measuring device calculator 26 to obtain the outer diameter of the preform 1 and the center of the preform 1 from the reference point. The displacement (displacement amount), the direction of displacement, the position where the outer diameter is changed, the average value of the outer diameter of the entire preform 1, and the shape data of the variation of the outer diameter of the entire preform 1 are calculated, and data storage is performed. 22 and printed by the printer at the same time.

Incidentally, the preform for an optical fiber obtained by stretching a single mother ingot is usually too long, having a total length of 10 m or more. Into a length of about 1 m. At this time, mark with a pen before cutting the preform,
By matching the direction when placing the cut preform 1 on the holding table 11, shape data of the entire preform before cutting can be obtained.

Using the shape measuring apparatus of the present invention, the length 1
000 mm, preform 1 with an outer diameter of 60 mm is 10 mm
The shape of 100 points was measured at intervals, and data obtained by calculating the outer diameter of the preform 1, the amount of displacement of the center point and the direction of displacement from the measured data were obtained. The result is shown in FIG. As shown in the figure, the amount of displacement of the outer diameter and the center point of the preform 1 and the manner in which the displacement direction changes can be accurately known, and the measurement time was as short as 60 seconds.

For comparison, the shape of the same preform 1 was measured using a conventional shape measuring device. However, since the preform 1 is supported by the support at two points at both ends,
Only the central portion 500 mm of the preform 1 was measured at 10 mm intervals, and the obtained measurement data was input to a computer to obtain data obtained by calculating the outer diameter of the preform 1, the amount of displacement of the center point, and the direction of displacement. FIG. 4 shows the results. As shown in the figure, each data had large variations and lacked accuracy, and the measurement time was as long as 7 minutes.

Next, in addition to the shape measuring apparatus of the present invention, one preform 1 having a length of 10000 mm and an outer diameter of 60 mm was cut into 10 pieces to a length of 1000 mm using an automatic conveying device. The shape was measured at intervals of 10 mm by placing the preforms 1 on the holding table 11 in the same direction, and data obtained by calculating the outer diameter, the displacement of the center point, and the displacement direction of the ten preforms 1 were obtained. The result is shown in FIG. As shown in the figure, the displacement amount of the outer diameter and the center point of the preform 1 and the manner in which the displacement direction changes can be continuously and accurately known, and the measurement time is 15 minutes (90 seconds / 1 line). ) And was short.

For comparison, the shape of the preform 1 similarly cut into 10 pieces was sequentially measured one by one using a conventional shape measuring device. However, preform 1 is 2
Since the point is supported by the support table, only the central portion of the preform 1 at 500 mm is measured at 10 mm intervals, the obtained measurement data is input to a computer, and the outer diameter of the preform 1, the displacement of the central point and the displacement The data for which the direction was calculated was obtained. FIG. 6 shows the result. As shown in the figure, the data is not continuous and lacks accuracy, and the measurement time is 80
Minutes (8 minutes / line).

[0021]

As described in detail above, when the shape of the preform for optical fiber is measured by the shape measuring apparatus of the present invention, the surface of the preform is not damaged, and it takes no time and effort. Measurement can be performed efficiently, and the accuracy of the shape data is high. In addition, if an automatic preform conveying device is used, the work of measuring the shape of the preform can be made almost unmanned.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of an apparatus for measuring the shape of an optical fiber preform to which the present invention is applied.

FIG. 2 is a control block diagram of an optical fiber preform shape measuring apparatus to which the present invention is applied.

FIG. 3 is a diagram showing preform shape data measured by an optical fiber preform shape measuring apparatus to which the present invention is applied.

FIG. 4 is a diagram showing shape data of a preform measured by a conventional optical fiber preform shape measuring apparatus.

FIG. 5 is a diagram showing shape data of another preform measured by an optical fiber preform shape measuring apparatus to which the present invention is applied.

FIG. 6 is a diagram showing shape data of another preform measured by a conventional optical fiber preform shape measuring apparatus.

[Explanation of symbols]

1 is an optical fiber preform, 2 is an outer diameter measuring device, 3 is a linear encoder, 4 is a motor, 5 is a laser irradiator, 6
Is a laser receiver, 7 is a scanning plate, 8 is a detection window, 10 is a control circuit, 11 is a holding table, 13 is a screw rod, 14 is a guide rail, 15 is a fixed table, 16 is a ball nut, 21 is a motor controller, 22 is a data storage, 25 is a linear encoder operation unit, and 26 is an outside diameter measuring unit operation unit.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-195505 (JP, A) JP-A-8-110281 (JP, A) JP-A-5-99789 (JP, A) 81678 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01M 11/00-11/02 G01B 11/00-11/30

Claims (3)

(57) [Claims] 1. A shape measuring device for measuring the shape of an optical fiber preform by irradiating light from a side thereof to the preform, comprising: a holding table on which the preform is placed; , from the axial direction perpendicular to the direction, out
An outer diameter measuring device for measuring the outer diameter of light by irradiating light with at least two laser irradiators whose emission light is orthogonal, a driving means for moving the outer diameter measuring device in a longitudinal direction of the preform; A shape measuring device for an optical fiber preform, comprising: a position detector for detecting a measurement position of a diameter measuring device. 2. The method according to claim 1, wherein the holding table is made of polytetrafluoroethylene.
Shape measuring apparatus of the preform for optical fiber according to claim 1, characterized in that it is made of down. 3. The apparatus for measuring the shape of an optical fiber preform according to claim 1, further comprising an automatic transport device for transporting the optical fiber preform to the holding table.