JPH09126946A - Optical fiber core thickness deviation measurement method - Google Patents

Abstract

(57) Abstract: An optical fiber capable of accurately measuring the uneven thickness of each coating even when the optical fiber diameter of the optical fiber core wire coated with two or more coating layers or the coating diameter varies. A method for measuring uneven thickness of a core wire is provided. SOLUTION: The light transmitted through the coating is incident on the optical fiber 3 core wire having at least one coating on the outer periphery of the optical fiber 3 from a direction perpendicular to the longitudinal direction of the optical fiber 3 core wire, In the method for measuring the uneven thickness of the optical fiber 3 core by detecting the forward scattered light and measuring the uneven thickness D of the coating, the uneven thickness D of the coating is measured by measuring the outer diameter dc1 of the layer to be measured before coating.
Then, the outer diameter dc2 of the layer to be measured is measured, and the measured value is used to measure the uneven thickness D ″ of the layer to be measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring an eccentricity of a coating of an optical fiber core wire, and more specifically, a method of measuring an eccentricity of an optical fiber core wire having a plurality of coating layers. Regarding

[0002]

2. Description of the Related Art The uneven thickness of the coating of an optical fiber core is caused by irradiating a light beam in a direction perpendicular to the longitudinal direction of the optical fiber core, that is, in the radial direction of the optical fiber core, and the left and right of the scattered light pattern. It is required based on symmetry. For example, in Japanese Unexamined Patent Publication No. 61-44336, the scattered light and the incident light irradiated onto the coated optical fiber from two directions of X and Y in the radial direction of the light beam are measured with a diode array, and the incident light and the scattered light are measured. It is divided into a region where both are incident (second region) and a region where only scattered light is incident (first region), and the rising and falling positions of the first region and the falling region of the second region of the respective pulse waveform signals are divided. There is disclosed a method for obtaining left and right eccentricity or eccentricity from the rising position.

Japanese Patent Publication No. 52207/1990 discloses that
In order to obtain the uneven thickness of each coating of the coated optical fiber having the two-layer coating, the coated optical fiber is irradiated with a light beam having excellent linearity from two directions of X and Y, and the scattered light peak position Left / right ratio (hereinafter simply referred to as the ratio of scattered light positions): The left / right ratio of the intensity of the scattered light peak detected by the light receiver (hereinafter simply referred to as the ratio of scattered light intensity): P is used to determine the uneven thickness of each coating. A method is disclosed.

Further, in each of the above methods, the uneven thickness is measured in the coating device after the coating has reached a steady state. Therefore, for example, when the uneven thickness of the primary coating is obtained, the optical fiber diameter is a predetermined value. When determining the uneven thickness of the secondary coating, it is premised that the primary coating outer diameter, wall thickness, etc. are formed normally. Therefore, in the case of the above-mentioned known method in which the optical fiber diameter and the coating diameter are constant and those values are input in advance to the thickness deviation detector, the linear velocity is changed to a desired value when the apparatus is started up. Since the coating diameter fluctuates when the linear velocity is fluctuating due to time or the fluctuation of the base metal diameter, especially when the cooling cannot be sufficiently performed by high-speed drawing,
There is a problem that the uneven thickness of each layer cannot be accurately measured individually.

The present invention solves the above-mentioned problems, and even if the optical fiber diameter or the coating diameter of the optical fiber core wire coated with two or more layers varies, the uneven thickness of each coating can be accurately measured. An object of the present invention is to provide a method for measuring the thickness deviation of an optical fiber core wire that can be measured.

[0006]

The present invention has the following means to solve the above problems.

According to a first aspect of the present invention, there is provided an optical fiber core thickness deviation measuring method, wherein an optical fiber core wire having at least one coating on an outer periphery of an optical fiber is used for transmitting light transmitted through the coating to the optical fiber. In an uneven thickness measuring method for an optical fiber core, which is incident from a direction perpendicular to the longitudinal direction of the fiber core wire and detects the forward scattered light to measure the uneven thickness of the coating, the measurement of the uneven thickness of the coating Is performed by using the outer diameter value of the layer to be measured before coating and the outer diameter value after coating.

According to a second aspect of the present invention, there is provided a method for measuring a thickness deviation of a fiber core wire, wherein the optical fiber core wire having at least one coating on the outer circumference of the optical fiber transmits the light transmitted through the coating to the optical fiber. Incident from the direction perpendicular to the longitudinal direction of the core wire, in the uneven thickness measuring method of the optical fiber core wire to detect the forward scattered light to measure the uneven thickness of the coating, the measurement of the uneven thickness of the coating, Outer diameter value before coating the layer to be measured,
The outer diameter value after coating is used, and if there is more than one coating on the outer circumference of the optical fiber before the coating of the layer to be measured, the uneven thickness of the coating is used to measure the uneven thickness of the coating. It is characterized by doing.

According to the uneven thickness measuring method of the optical fiber core wire of the present invention, the light transmitted through the coating is perpendicular to the longitudinal direction of the optical fiber core wire, that is, the radial direction of the optical fiber core wire. When the incident light is further incident and the forward scattered light is detected to measure the uneven thickness, the uneven thickness is measured using the outer diameter values of the layer to be measured before and after coating. For example, in the case of the primary coating, the uneven thickness of the primary coating is measured by detecting the forward scattered light with reference to the outer diameter of the optical fiber and the outer diameter of the primary coating, and in the case of the secondary coating, the outer diameter of the primary coating and Since the uneven thickness of the secondary coating is measured by detecting the forward scattered light with the outer diameter of the secondary coating as the reference, even when the coating device is started up or the coating thickness is changing, The eccentricity of the layer coating can be measured individually and accurately.

According to the method for measuring the uneven thickness of the fiber core wire of the second aspect of the present invention, the uneven thickness of the coating is measured by detecting the forward scattered light of the layer to be measured, and measuring the outer diameter before and after the coating. Measurement, and if there is at least one coating on the outer circumference of the optical fiber before the coating of the layer to be measured, the measurement of the uneven thickness is used. Even when the linear velocity changes and the coating thickness changes, the uneven thickness of the coating of each layer can be individually and accurately measured.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. FIG. 1 shows an optical fiber drawing apparatus used in an embodiment of a method for measuring the thickness deviation of an optical fiber according to the present invention. The optical fiber preform 1 is heated in the drawing furnace 2 and the spun optical fiber 3 is cooled by the cooling device 5. The cooled optical fiber 3 is coated with the UV resin by the first coating device 6A, and the coated UV resin is cured by the UV lamp 7A. The optical fiber 3 coated with the UV resin is coated with the second layer of the UV resin by the second coating device 6B and cured by the UV lamps 7B and 7C,
An optical fiber 3 having a two-layer coating is formed to form a take-up machine 1
It is pulled out by 2 and wound by the winder 13.

In the above drawing device, the outer diameter df of the optical fiber 3 is measured between the drawing furnace 2 and the cooling device 5 by the optical fiber outer diameter measuring device 4. Outer diameter dc1 of the coated fiber 3 coated with the first layer after being coated with the first layer and cured
Is measured by the first coating outer diameter measuring device 8 provided below the UV lamp 7A. UV after the second coating is cured
The coating diameter dc2 of the optical fiber 3 having the two-layer coating by the second coating outer diameter measuring device 10 provided below the lamp 7C.
Is measured. The first thickness deviation detector 9 is provided below the first outer diameter measuring device 8 to measure the thickness deviation D ′ of the first layer coating. The second thickness deviation detector 11 is provided below the second outer diameter measuring device 10, and the thickness deviation D ″ of the coating of the second layer is detected by the second thickness deviation detector 11.
Measure with.

The first and second thickness deviation detectors 9 and 11 have a detector and a controller, and the scattered light data signal measured by the detector is sent to the controller. In addition, the first thickness deviation detector 9
To the optical fiber outer diameter measuring instrument 4 outer diameter df data signal and the first outer diameter measuring instrument 8 from the outer diameter dc1 data signal of the coating of the first layer is sent, based on that The optical fiber diameter and the eccentricity of the coating are calculated. Second thickness deviation measuring device 11
The scattered light data signal measured by the detector, the eccentricity D data signal of the first layer, and the data signal of the eccentricity angle θE are sent from the first eccentricity detector 9. Further, a data signal of the coating diameter dc2 of the coating of the second layer is sent from the second outer diameter measuring device 10,
The uneven thickness D ″ of the second layer is calculated based on those data signals.

FIG. 2 shows the relationship between the amount of uneven thickness and the ratio S of scattered light positions.
Shown in The relationship between the coating diameter and the scattered light position ratio S is shown in FIG. From this, it can be seen that the amount of uneven thickness varies depending on the coating diameter even if the value of the ratio S of scattered light positions is the same. Specifically, the points S and B in FIG. 2 are on the 200 scale where the ratio S of the scattered light positions is almost the same, but the point A has a thickness deviation of 7 μm when the coating diameter is 195 μm, but the point B is Coating diameter is 197.5
μm, the uneven thickness is 5 μm. Since the ratio S of the scattered light positions depends on the coating diameter or the outer diameter before coating as described above, the uneven thickness measuring method of the optical fiber core wire according to the present invention using the coating diameter and the outer diameter before coating accurately determines the uneven thickness. It will be possible to measure.

Known laser measuring instruments are used as the first outer diameter measuring instrument 8 and the second outer diameter measuring instrument 10. When measuring the outer diameter of a running optical fiber or a coated optical fiber with an outer diameter measuring instrument, the correct value may not be measured due to the vibration of the optical fiber or the coated optical fiber or their temperature, but they are Therefore, it is possible to make corrections by storing calibration data corresponding to the linear velocity in the control unit in advance. A means for measuring the outer diameter may be built in the thickness deviation measuring device. In this case, the optical fiber passing through the coating device provided in front of the thickness deviation measuring device or the outer diameter data signal of the coating optical fiber must be input to the control unit of the thickness deviation measuring device. Space saving can be achieved by integrating the thickness deviation measuring device and the outer diameter measuring device.

As the first and second thickness deviation detectors, for example, those shown in FIG. 4 are used. Reference numeral 3 is an optical fiber having a coating whose uneven thickness is to be measured, a so-called optical fiber core wire. Reference numeral 20 denotes an uneven thickness measuring unit that measures the uneven thickness of the optical fiber core wire 3. The thickness deviation measuring unit 20 includes a laser light source 21 that emits a pair of light beams and a photodetector 22 that includes a diode array. Laser light source 21 and photodetector 22
Are mounted on the rotary stage 23 such that the three members are arranged in a straight line with the optical fiber core wire 3 interposed therebetween in the radial direction perpendicular to the longitudinal direction of the optical fiber core wire 3. The rotary stage 23 is rotatably mounted via a roller 26 and a bearing 27 on a measurement base 25 having a through hole 24 through which the optical fiber core wire 3 is inserted.

A gear 28 is provided on the outer circumference of the rotary stage 23 and is fitted with a gear 30 provided on the rotary shaft of the stepping motor 29. The drive of the stepping motor 29 causes the rotary stage 23 to move at a predetermined angle. For example, it is designed to rotate by 1 °. An encoder 31 is attached to the stepping motor 29, and the rotation angle of the stepping motor 29 is detected to detect the rotation angle of the rotary stage 23. A cover 32 having a through hole through which the optical fiber core wire 3 is inserted so as to prevent excess ambient light from entering the photodetector 22 is provided above the rotary stage 23.

A method for measuring the thickness deviation of the optical fiber core wire 3 being drawn by the thickness deviation measuring unit 20 having the above-described structure will be described below. With the optical fiber core wire 3 being drawn set in the thickness deviation measuring section 20, the optical axes of the laser light source 21 and the photodetector 22 are set together, and light is emitted from the laser light source 21 in the state of being irradiated with a light beam. The rotation stage 23 is driven by driving the stepping motor 29 around the fiber core wire 3.
Is rotated by a predetermined angle, for example, 1 ° while rotating forward scattered light transmitted through the optical fiber core wire 1 by the photodetector 12, and is rotated once, and the forward scattered light at each angle is shown in FIG. , (B), the ratio S of the scattered light positions on the left and right of the pattern and the ratio P of the scattered light intensity are obtained. The ratio S of the left and right scattered light and the ratio P of the scattered light intensity have a peak at a specific position as shown in FIG. 6, and the angle at this peak is an angle inclined by approximately 90 ° with respect to the scattering angle.

The amount of uneven thickness can be obtained from the value of the ratio S of the scattered light position and the ratio P of the scattered light intensity as follows. First, a conversion table for the amount of thickness deviation is created by measuring the ratio S of the scattered light position and the ratio P of the scattered light intensity of the optical fiber core wire whose amount of thickness unevenness is known in advance. Next, the ratio S of the scattered light position and the ratio P of the scattered light intensity of the optical fiber core wire of which the amount of thickness deviation is unknown are measured, and the amount of thickness deviation is obtained from the obtained measured value based on the conversion table.

[0020]

As described above, according to the method for measuring the uneven thickness of the optical fiber core wire according to the first aspect of the present invention, the light transmitted through the coating is directed in a direction perpendicular to the longitudinal direction of the optical fiber core wire. That is, when measuring the uneven thickness by detecting the forward scattered light incident from the radial direction of the optical fiber core, measure the uneven thickness using the outer diameter value of the layer to be measured before and after coating. To do. For example, in the case of the primary coating, the uneven thickness of the primary coating is measured by detecting the forward scattered light with reference to the outer diameter of the optical fiber and the outer diameter of the primary coating, and in the case of the secondary coating, the outer diameter of the primary coating and Since the uneven thickness of the secondary coating is measured by detecting the forward scattered light with the outer diameter of the secondary coating as the reference, even when the coating device is started up or the coating thickness is changing, The eccentricity of the layer coating can be measured individually and accurately.

As described above, according to the method of measuring the uneven thickness of the fiber core wire according to the second aspect of the present invention, the uneven thickness of the coating is measured by detecting the forward scattered light of the layer to be measured and before the coating. Since the outer diameter after coating is measured and the measured value is used, and if there is at least one coating on the outer circumference of the optical fiber before the coating of the layer to be measured, the measured value of the uneven thickness is used. Even when the linear velocity at the time of starting the coating apparatus is changed or the coating thickness is changed, the uneven thickness of the coating of each layer can be individually and more accurately measured.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an optical fiber drawing device used in an embodiment of a method for measuring thickness deviation of an optical fiber according to the present invention.

2 is an explanatory diagram of a relationship between a thickness deviation amount and a scattered light position ratio S in the optical fiber drawing device of FIG. 1;

3 is an explanatory diagram of a relationship between a coating diameter and a scattered light position ratio S in the optical fiber drawing device of FIG.

FIG. 4 is an explanatory view showing an example of a thickness deviation detector used in the method for measuring thickness deviation of the optical fiber core wire in FIG. 1.

FIG. 5 is an explanatory diagram showing a relationship between a ratio S of scattered light positions or a ratio P of scattered light intensities and an amount of uneven thickness.

FIG. 6 is an explanatory diagram showing a relationship between a ratio S of scattered light positions or a ratio P of scattered light intensities and an amount of uneven thickness.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical fiber base material 2 Drawing furnace 3 Optical fiber 4 Optical fiber outer diameter measuring instrument 5 Cooling device 6A, 6B Coating device 7A, 7B, 7C UV lamp 8 First coating outer diameter measuring instrument 9 First polarization Meat detector 10 Second outer diameter measuring device for coating 11 Second uneven thickness detector D Eccentricity amount D'Eccentricity amount D '' Eccentricity amount dc1 First coating outer diameter dc2 Second coating outer diameter df Optical fiber outer diameter θE Eccentric angle

Claims (2)

[Claims] 1. An optical fiber core wire having at least one layer of coating on the outer periphery of an optical fiber, and light incident through the coating is incident from a direction perpendicular to the longitudinal direction of the optical fiber core wire, In the uneven thickness measuring method of the optical fiber core wire for detecting the forward scattered light and measuring the uneven thickness of the coating,
An uneven thickness measuring method for an optical fiber core wire, wherein the uneven thickness of the coating is measured by using an outer diameter value of a layer to be measured before coating and an outer diameter value after coating. 2. An optical fiber core wire having at least one coating on the outer circumference of an optical fiber, and light incident through the coating is incident from a direction perpendicular to the longitudinal direction of the optical fiber core wire. In the uneven thickness measuring method of the optical fiber core wire for detecting the forward scattered light and measuring the uneven thickness of the coating,
The uneven thickness of the coating is measured by using the outer diameter value of the layer to be measured before coating and the outer diameter value after coating, and one or more coatings on the outer circumference of the optical fiber before coating the layer to be measured. If there is a thickness deviation, the thickness deviation of the coating is measured to measure the thickness deviation of the optical fiber core wire.