JP2003035631A - Method for optimizing residual strain value of optical fiber unit wire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for optimizing a residual strain value of an optical fiber unit wire which is designed to eliminate effects onto forming a cable or installing a cable on the basis of a residual strain optimum value, by recognizing the residual strain optimum value of the optical fiber unit wire beforehand. SOLUTION: A plurality of optical fiber units are prepared. A residual strain of each of the prepared optical fiber units is measured by a residual strain- measuring apparatus 1. At the same time, each of a high-temperature test, a hydraulic test and a bending test is also carried out to each of the optical fiber units whose residual strain is measured. The optical fiber unit having the measured value of each test within a permissible value is extracted from the result of the three tests. When the residual strain measured value measured by the residual strain-measuring apparatus 1 of the extracted optical fiber unit is within a preset permissible value, the residual strain measured value is made the optimum value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for optimizing the residual strain of an optical fiber unit wire for determining the optimum value of the residual strain of the wire in an optical fiber unit.

[0002]

2. Description of the Related Art The tension applied to an optical fiber when an optical fiber unit is assembled remains as a strain after the unit is assembled. The distortion at the time of the unit is an important parameter because it has an influence after the cable is formed or the cable is attached later.

The residual strain of a conventional optical fiber unit is
The allowable value is 0 to 5% in consideration of stretching during the cable forming process and compression during installation on the seabed.

However, the optimum amount of strain is not known among the allowable values, and it has not been tried until now.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and its purpose is to obtain the optimum residual strain value of an optical fiber unit strand by knowing it in advance. Based on the above, it is an object of the present invention to provide a method for optimizing the residual strain of an optical fiber unit element wire that does not affect cable formation and cable attachment.

[0006]

In order to achieve the above object, the method for optimizing the residual strain of an optical fiber unit wire of the present invention according to claim 1 prepares a plurality of optical fiber units. The residual strain of each optical fiber unit is measured with a residual strain measuring device, and each optical fiber unit whose residual strain is measured is subjected to a high temperature test, a water pressure test and a bending test in combination, and these three tests are performed. From each result, extract the optical fiber unit in which each measured value is within the allowable value in each test, and the residual strain measurement value measured by the residual strain measuring instrument of the extracted optical fiber unit is within the preset allowable value. In this case, the residual strain measurement value is set to the optimum value.

Therefore, a plurality of optical fiber units are prepared, and the residual strain of each prepared optical fiber unit is measured by the residual strain measuring device. Then, each test of the high temperature test, the water pressure test and the bending test is performed on each optical fiber unit whose residual strain is measured,
From these three test results, an optical fiber unit in which each measured value is within the allowable value is extracted in each test. When the residual strain measurement value measured by the residual strain measuring device of the extracted optical fiber unit is within the preset allowable value, the residual strain measurement value is determined as the optimum value.

As a result, the optimum residual strain value is used so as not to affect future cable formation and cable attachment.

According to a second aspect of the present invention, there is provided a method for optimizing residual strain of an optical fiber unit strand according to the first aspect of the present invention, which is the residual strain optimizing method for optical fiber unit strand according to the first aspect. , The number of cores of the unit, and the unit length are known, and both ends of the optical fiber unit are output, and both ends of the optical fiber unit are connected to the signal generator and the vector voltmeter by loop connection to the signal generator. It is characterized in that a phase change of the optical fiber unit is measured by giving a frequency known in advance, and the residual strain is calculated based on the measured phase change.

Therefore, both ends of the optical fiber unit whose core number and unit length are known in advance are put out, and both ends of the optical fiber unit are loop-connected to generate respective signals in the residual strain measuring instrument. And a vector voltmeter and the signal generator is provided with a known frequency to measure the phase change of the optical fiber unit. Based on this measured phase change, the residual strain is
Calculated more accurately.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described in detail with reference to the drawings.

Referring to FIG. 1, the residual strain measuring instrument 1 is
A signal generator 3 and a vector voltmeter 5 are provided, and the signal generator 3 and the vector voltmeter 5 have an E / O (electrical / optical converter) 7 and an O / E (optical / electrical converter) 9 respectively. Are connected. And this E / O (electrical / optical converter) 7
A sample 11 as a plurality of optical fiber units prepared in advance is connected between the optical fiber and the O / E (optical / electrical converter) 9 and the phase change before and after disassembly is measured. In addition, a plurality of optical fiber units as the sample 11 are connected to the E / O (electrical / optical converter) 7 and the O / E (optical / electrical converter) 9 by loop connection with both ends exposed. The vector voltmeter 5 is connected to an arithmetic unit 13 that calculates the residual strain based on the phase change measured by the vector voltmeter 5. The signal generator 3 and the vector voltmeter 5 are directly connected by a signal line 15.

With the above configuration, the number of cores X of the unit is preset.
1. Prepare a plurality of, for example, four optical fiber units whose unit length L1 (m) is known. Then, for example, the unit NO. 1 at both ends, and by loop connection, the unit NO. Both ends of 1 are connected to an E / O (electrical / optical converter) 7 and an O / E (optical / electrical converter) 9, respectively, and the signal generator 3 has a frequency f1 (MH
z) is applied, the vector voltmeter 5 measures the voltage B with respect to the reference voltage A, and the voltage difference causes the unit NO. A phase change θ1 of 1 is measured.

Next, the number of cores X of the unit prepared in advance
2, X3, X4, unit lengths L2, L3, L4 (m) are known. 2, unit NO. 3, unit NO. 4 as described above, the signal generator 3
Frequencies f2, f3, f4 (MHz) that are known in advance
By operating the unit NO. 2, unit NO. 3, unit NO. Phase change of 4 θ2, θ3, θ
4 is measured. This measured phase change θ1, θ2,
When θ3 and θ4 are taken into the arithmetic unit 13, the residual strain ε in the arithmetic unit 13 is calculated by the equation ε = 71.25 * θ /
It is calculated by (f × L × X). This calculated ε
1, ε2, ε3, ε4 are as shown in Table 1,
It is 0.010, 0.035, 0.050, and 0.100%.

The residual strains ε1, ε2, ε3, and ε4 for which the unit NO. 1, unit NO. 2, unit NO. 3, unit NO. 4 using JI
The results of the high temperature test, water pressure test, and bending test determined by S are shown in FIGS. 2, 3, and 4. In FIG. 2, the loss increase value (mdB / k
m) is 10 to 15 (mdB / km), and the unit No. 2, unit NO. 3 is good, unit no.
1, unit NO. It can be seen that 4 is defective. Figure 3
In the hydraulic pressure test result, loss increase value (mdB / km)
The allowable value of 10 (mdB / km) or less, the unit N
O. 1, unit NO. 2 is good, unit no. 3, unit NO. It can be seen that 4 is defective. In addition, similarly, in FIG. 4, the loss increase value (mdB
/ Km) has an allowable value of 3 (mdB / km) or less, the unit No. 2 is good, unit no. 1, unit NO.
3, unit NO. It can be seen that 4 is defective.

The above results are summarized in Table 1 below.

[0017]

[Table 1] From this result, the unit No. No. 2 was the most excellent in all the allowable values in the high temperature test, water pressure test, and bending test, and this unit NO. The optimum value was 0.035 ± 0.005% of the residual strain of 2.
Therefore, based on this optimum value, it can be used so as not to affect future cable formation and cable attachment.

The present invention is not limited to the above-described embodiment, but can be implemented in other modes by making appropriate changes.

[0019]

As can be understood from the above description of the embodiment of the invention, according to the invention of claim 1, a plurality of optical fiber units are prepared, and the prepared optical fiber units remain. The strain is measured with a residual strain gauge. Then, each optical fiber unit whose residual strain was measured was subjected to a high temperature test, a water pressure test, and a bending test in combination, and from these three test results, the light values for which the respective measured values were within the allowable values were obtained. The fiber unit is extracted. When the residual strain measurement value of the extracted optical fiber unit measured by the residual strain measurement device falls within a preset allowable value, this residual strain measurement value can be determined as an optimum value.

As a result, based on this determined optimum value of the residual strain, it is possible to use the cable without affecting future cable formation and cable attachment.

According to the second aspect of the present invention, both ends of the optical fiber unit whose core number and unit length are known in advance are exposed, and both ends of the optical fiber unit are connected by loop connection so as to eliminate residual strain. It is possible to connect the signal generator and the vector voltmeter in the measuring device, respectively, and give the signal generator a known frequency to measure the phase change of the optical fiber unit. The residual strain can be calculated more accurately based on the measured phase change.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a residual strain measuring instrument used in the present invention.

FIG. 2 is a graph showing a relationship between a residual strain and a loss increase value as a result of performing a high temperature test using each optical fiber unit measured by a residual strain measuring instrument.

FIG. 3 is a graph showing the relationship between the residual strain and the loss increase value as a result of a water pressure test using each optical fiber unit measured by a residual strain measuring instrument.

FIG. 4 is a graph showing a relationship between a residual strain and a loss increase value as a result of performing a bending test using each optical fiber unit measured by a residual strain measuring instrument.

[Explanation of symbols]

1 Residual strain measuring instrument 3 signal generator 5 vector voltmeter 7 E / O (electrical / optical converter) 9 O / E (optical / electrical converter) 11 samples 13 Arithmetic device 15 signal lines

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Keiko Mitsuhashi             1440 Rokuzaki, Sakura City, Chiba Prefecture Fujikura Ltd.             Sakura office (72) Inventor Takeshi Shimichi             1440 Rokuzaki, Sakura City, Chiba Prefecture Fujikura Ltd.             Sakura office (72) Inventor Keiji Ohashi             1440 Rokuzaki, Sakura City, Chiba Prefecture Fujikura Ltd.             Sakura office F-term (reference) 2G086 DD05

Claims (2)

[Claims] 1. A plurality of optical fiber units are prepared, the residual strain of each prepared optical fiber unit is measured by a residual strain measuring instrument, and a high temperature test is performed on each optical fiber unit whose residual strain is measured. , A water pressure test and a bending test are performed together, and an optical fiber unit in which each measured value is within an allowable value is extracted from the three test results, and the residual strain of the extracted optical fiber unit is extracted. A method for optimizing the residual strain of an optical fiber unit element wire, wherein the residual strain measurement value is set to an optimum value when the residual strain measurement value measured by a measuring device falls within a preset allowable value. 2. A residual strain measuring instrument, wherein both ends of an optical fiber unit whose core number and unit length are known in advance are output, and a signal generator is provided at both ends of the optical fiber unit by loop connection. , Is connected to a vector voltmeter, gives a signal generator a known frequency, measures the phase change of the optical fiber unit, and calculates the residual strain based on the measured phase change. The method for optimizing the residual strain of an optical fiber unit element wire according to claim 1, wherein.