JPH04231837A - Method for collectively measuring optical fibers - Google Patents

Abstract

PURPOSE:To simply and collectively measure optical fibers with low loss and high reliability by a single measuring device without gathering fibers to be measured dispersed in places to the vicinity of a connection part. CONSTITUTION:An OTDR 20 and a plurality of dummy fibers 12a are optically connected so as to be freely changed over by a light path change-over device 11 having an adaptor and an optical connector and a plurality of dummy fibers 12a are respectively abutted and connected to a plurality of fibers 13a to be measured by a connection part 13 and the inspection light from the OTDR 20 is emitted to the respective fibers 13a to be measured through the dummy fibers 12a while it is changed over by the light path change-over device 11 to collectively and optically measure a plurality of the fibers 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 collectively measuring optical fibers in which a plurality of optical fibers are temporarily butt-connected and optically measured.

0002

[Prior Art] Optical time measurement (OTDR) is used to optically measure optical fiber breakage, transmission loss, etc. in an optical fiber cable consisting of a plurality of optical fibers.
For example, as shown in FIG.
The end of the dummy fiber 2 connected to the dummy fiber 2 is butt-connected to the end of the fiber under test 4 at the connection part 3, and the test light emitted from the OTDR 1 is emitted to the fiber under test 4 via the dummy fiber 2. By measuring the backscattered light returning from 4, optical measurements such as wire breakage and transmission loss are performed.

By the way, when measuring a large number of fibers to be measured using the above-mentioned measurement system using an OTDR, the OTD
Prepare as many R as the number of fibers to be measured, or
Using a single OTDR, it is necessary to sequentially switch each of the multiple fibers under test to a dummy fiber at the connection point. However, since OTDRs are expensive, optical measurements are usually performed using the latter method, in which a single OTDR is used and a large number of fibers to be measured are sequentially switched to dummy fibers at the connection point.

[0004] When measuring a large number of fibers to be measured using a single OTDR in this way, if the fibers to be measured are dispersed, each fiber to be measured must be gathered near the connection part. The efficiency of measurement work was greatly reduced. For this reason, an optical channel selector is used that switches the test light emitted from the OTDR to a large number of dummy fibers optically connected to each fiber under test.

[0005] Such an optical channel selector is, for example,
As shown in FIG. 10, two common adapters 5, five channel adapters 6, two switching fibers 7 having a connector 7a connected to each common adapter 5 at one end and a cylindrical lens 7b at the other end, A connector 8a connected to each channel adapter 6 is attached to one end, and a cylindrical lens 8b is attached to the other end.
five switching fibers 8 having a
It is equipped with

[0006]

[Problems to be Solved by the Invention] By the way, in the above-mentioned optical fiber measurement, the channel selector uses a prism to switch the path of the inspection light, so it is difficult to 3 losses each
．． It is about 5 dB. Therefore, the optical loss in the round trip is 7d.
B, the level of scattered light measured by the OTDR decreases and the measured waveform is disturbed, resulting in a reliability problem for accurate waveform analysis.

The present invention has been made in view of the above points, and it is possible to easily and low-loss measure a plurality of fibers to be measured, which are dispersed in various locations, using a single measuring device without concentrating them near the connection part. The purpose of this invention is to provide a method for batch measurement of optical fibers that can be measured all at once with high reliability.

[0008]

[Means for Solving the Problems] In order to achieve the above object, according to the method of the present invention, an OTDR and a plurality of dummy fibers are optically connected in a switchable manner by an optical path switching device having an adapter and an optical connector. At the same time, each of the plurality of dummy fibers is butt-connected to each of the plurality of fibers to be measured at the connection part, and the test light from the OTDR is
The plurality of fibers to be measured are optically measured at once by sequentially switching and emitting light to each of the plurality of fibers to be measured via the plurality of dummy fibers by the optical path switching device.

[0009] Here, OTDR refers to an optical reflectometer (Optical T
ime Domain Re-flectometer
).

0010

[Operation] The test light emitted from the OTDR is switched by an optical path switching device, emitted to each of a plurality of dummy fibers, and transmitted to each corresponding measured fiber optically connected to the dummy fiber at the connection part. . The test light incident on each fiber under test returns to the OTDR through a path opposite to the above due to back scattering within the fiber under test during transmission. Such operations are performed on a plurality of fibers to be measured, and optical measurements on each fiber to be measured are performed at once.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the method of the present invention will be described in detail below with reference to FIGS. 1 to 5. FIG. 1 shows an optical measurement system that implements the optical fiber batch measurement method of the present invention, in which an optical reflectometer 10, a channel selector 11
, a multi-core dummy fiber 12, a butt jig 13, a multi-core fiber to be measured 14, and a control/processing device 15.
Optical reflectometer 10 and control/processing device 15 are OT
It constitutes DR20.

The optical reflectometer 10 is connected to the channel selector 11 through a single-core connecting fiber 16, and outputs inspection light from a light source (not shown) to the connecting fiber 16, and returns it from the multi-core fiber 14 to be measured by Rayleigh scattering. This is a measuring device that receives scattered light. The channel selector 11 switches the optical path for emitting the inspection light, and as shown in FIG. 2, includes a common adapter 11a, four switching adapters 11b, a switching fiber 11c consisting of a single optical fiber, and a switching connector 11d. ing. The common adapter 11a has a connector 16a attached to its tip.
The connecting fiber 16 is connected from the outside, and the switching fiber 11c is connected to the switching connector 11d. Further, the switching connector 11d is inserted into and removed from each switching adapter 11b and moved in the direction of arrow A in the figure by a drive mechanism (not shown), and these operations are controlled by the control/processing device 15.

The multi-core dummy fiber 12 is a four-core tape fiber, and both ends are separated into optical fiber cores 12a, and each optical fiber core 12a is subjected to terminal treatment such as removal of coating. One end of each optical fiber core 12a is connected to each switching adapter 11b of the channel selector 11 by a connector 12b (see FIG. 2), and the other end is connected to each switching adapter 11b of the channel selector 11 (see FIG. 2).
As shown in FIG. 2, the tip is brought into contact with each V-groove 13a of the butt jig 13 with the tip side bent.

The butt jig 13 is a multi-core dummy fiber 1
2 and the multi-core fiber 14 to be measured.
A connection part for making a temporary optical connection by butting a and 14a together,
A plurality of V grooves 13a are formed on the surface for positioning each optical fiber core 12a, 14a. The multi-core fiber 14 to be measured is, for example, a four-core tape fiber as a manufactured product, and as shown in FIG. 1, one end side is separated into optical fiber cores 14a, and each optical fiber core 14a has a , terminal treatment such as coating removal is performed. Then, one end of each optical fiber core wire 14a that has been terminal-treated is attached to the butt jig 1.
The tip is bent at each of the V-grooves 13a of No. 3 and is butt-connected to each optical fiber core wire 12a of the multi-core dummy fiber 12.

The control/processing device 15 is a control unit (ECU)
15a and a display section 15b, and as shown in FIG.
0 and channel selector 11. The control section 15a controls the operation of the channel selector 11, analyzes the waveform of the scattered light from the multicore fiber 14 under test, and displays the processing result on the display section 15b.

The optical measurement system is constructed as described above, and in the method of the present invention, this measurement system is used to collectively measure the multi-core fiber 14 to be measured as follows. First, prior to the batch measurement of the multi-core fibers 14 to be measured, the multi-core dummy fiber 12 is separated into optical fiber cores 12a at both ends, and each of the emerging optical fiber cores 12a is subjected to terminal treatment. put.

Next, one end of each optical fiber 12a is
It is connected to each switching adapter 11b of the channel selector 11, and the other end is brought into contact with the V-groove 13a of the butt jig 13 and bent. Next, the multicore fiber to be measured 14
One end of each coated optical fiber 14a is separated, and each coated optical fiber 14a is subjected to terminal treatment. This multi-core fiber 14 to be measured is connected to one end side of each optical fiber core 14a in a V-groove 13.
As shown in FIGS. 3 to 5, while bending each
It is butt-connected to each optical fiber core wire 12a of the multi-core dummy fiber 12.

Next, the control section 15a of the control/processing device 15
A command is transmitted to the optical reflectometer 10, and the optical reflectometer 10 emits inspection light. The inspection light emitted from the optical reflectometer 10 is connected to the connecting fiber 1
6 and enters the switching fiber 11c from the common adapter 11a of the channel selector 11. In the case shown in FIG. 2, the inspection light incident on the switching fiber 11c is incident on the first optical fiber core 12a located on the left end via the connector 12b of the multi-core dummy fiber 12 from the switching adapter 11b on the left end. and is transmitted through the optical fiber 12a.

Next, in FIG. 1, the inspection light transmitted through the first optical fiber core 12a is
The light enters the first optical fiber core 14a which is butt-connected at the groove 13a, and is transmitted. Scattered light scattered backward while the test light propagates within the optical fiber core 14a returns to the optical reflectometer 10 through a path opposite to the above.

The scattered light returned to the optical reflectometer 10 undergoes waveform analysis processing in the control section 15a of the control/processing device 15, and optical The measurement results are displayed on the display section 15b. In this way, when the optical measurement of the first optical fiber core 14a of the multi-core fiber 14 under test is completed, the switching connector 11d shown in FIG. , move to the right along arrow A.

Thereafter, a command is sent from the control section 15a to the channel selector 11, and the switching connector 11d is inserted into the second switching adapter 11b from the left end to switch the optical path. Thereby, the inspection light is incident on the second optical fiber core 14a of the multi-core fiber 14 to be measured,
A similar analysis process is performed on the returning scattered light,
The results are displayed on the display section 15b.

Hereinafter, in the same manner, the multi-core fiber 1 to be measured
Scattered light analysis processing is performed on all the optical fibers 14a of No. 4, and optical measurements are performed on the multi-core fiber 14 to be measured while butt-connected to the multi-core dummy fiber 12 on the butt jig 13. It is done all at once. Using the optical measurement system described above, the inspection light was incident on the multi-core fiber 14 to be measured according to the method of the present invention, and the waveform of the returned scattered light was analyzed.
The insertion loss associated with the round trip of the inspection light due to 1.1 is approximately 1.
2 dB, which is an average reduction of 5.8 dB compared to the conventional prism type channel selector.

Furthermore, since the insertion loss of the test light is reduced, the level of the scattered light returning from the multi-core fiber 14 to be measured is less reduced, and the processing time required for waveform processing of the scattered light is significantly reduced. The working time was reduced to 10 seconds or less using the method of the present invention, whereas it took 30 seconds to measure a four-core tape fiber using the conventional method. Next, a second embodiment of the present invention will be described based on FIG. 6, in which the fiber to be measured is a single-core optical fiber. In each of the embodiments described below, the same constituent members as in the previous embodiment are denoted by the same reference numerals in the drawings, and the explanation thereof will be omitted.

In this embodiment, single-core fibers to be measured 31a to 31d are wound around each bobbin 30, and one end of each fiber to be measured 31a to 31d unwound from each bobbin 30 is subjected to terminal treatment. and are butt-connected to each of the single-core dummy fibers 32a to 32d on each butt jig 13. On the other hand, one end is the fiber to be measured 31a.
The dummy fibers 32a to 32d are butt-connected to one end of the fibers 32a to 31d, respectively, and the other ends thereof are respectively connected to the switching adapter 11b of the channel selector 11.

Therefore, each of the fibers to be measured 31a to 3
1d optical measurement, first, the control/processing device 1
The control unit 15a of the channel selector 11 transmits a command to the optical reflectometer 10 to emit a test light, and the test light is made to enter the switching fiber 11c from the common adapter 11a of the channel selector 11 via the connection fiber 16. Then, the inspection light incident on the switching fiber 11c is incident on the first measured fiber 31a from the left end switching adapter 11b via the dummy fiber 32a, and is transmitted within this optical fiber 31a.

The scattered light that is scattered backward while the test light propagates within the fiber to be measured 31a returns to the optical reflectometer 10 through the opposite path to the above, and is controlled and
A waveform analysis process is executed by the control unit 15a of the processing device 15, and the result of the optical measurement regarding the first fiber to be measured 31a is displayed on the display unit 15b. In this way, when the optical measurement on the first fiber to be measured 31a is completed, the switching connector 11d is switched in response to a command from the control unit 15a, and the test light is transmitted to the second fiber through the second dummy fiber 32b. After similar analysis processing is performed by the control unit 15a on the scattered light that is emitted to the fiber to be measured 31b and returns, the results of the optical measurement are displayed on the display unit 15b.

Thereafter, optical measurements regarding the third and fourth fibers to be measured 31c and 31d are performed at once in the same manner. As described above, in this embodiment, since the butting jig 13, that is, the connecting portions are provided at a plurality of locations, the O
While the TDR 20 is performing optical measurement and analysis processing on the fiber under test 31a, other fibers under test 31b to 31
d terminal processing and setting to the butt jig 13 can be performed, and measurement time can be shortened.

Further, the number of fibers of the dummy fiber and the fiber to be measured is not particularly limited. For example, as shown in FIG.
2 is used, and the fibers to be measured 31 wound around each bobbin 30 are butt-connected to the dummy fibers 32 on the connection parts provided at two locations, that is, the butt jig 13. It is also possible to perform optical measurements on the measurement fibers 31, 31 all at once.

Next, as a third embodiment of the present invention, instructions regarding the start and end of measurement of each of the fibers to be measured 31a to 31d and the results of optical measurements are placed near each butting jig 13 serving as a connection part. An embodiment in which the display instruction/display mechanisms 40 are respectively arranged will be described based on FIG. 8. In this embodiment, an instruction/display mechanism 40 is arranged near each matching jig 13, and the instruction/display mechanism 40 is, for example, a combination of a push button switch and an indicator lamp, or a numeric keypad and a CRT. things etc. are used.

When the optical measurement system is configured in this way, even if each butting jig 13 is located at a distance from the OTDR 20, the operator can use the OTDR 20 for each optical measurement.
There is no need to return to position 20. Therefore, the operator can give instructions regarding output of the inspection light to the dummy fibers 32a to 32d, switching of the switching connector 11d in the channel selector 11, etc. to each matching jig 13 at the work site.
This can be done by remote control near the machine, further improving work efficiency.

In the above embodiment, the channel selector 11 has four switching adapters 11b, that is, four ports, but it goes without saying that this is not limited to this. No need to connect. Further, the multi-core dummy fiber and the multi-core fiber to be measured are butt-connected using a butt jig 13, but the optical fibers having the same number of fibers are butt-connected using the butt jig 13. The two pieces may be butt-connected using the butt jig 13, and the combination is arbitrary.

[0032]

Effects of the Invention As is clear from the above explanation, according to the optical fiber batch measurement method of the present invention, a plurality of fibers to be measured that are scattered here and there can be measured into a single fiber without gathering them near the connection part. Using a measuring device, it is possible to easily measure all at once with low loss and high reliability.

Furthermore, since the loss of the scattered light that returns due to the back scattering of the test light is reduced and the method is simple, it is possible to optically measure the fiber under test in a short time and with high precision.
It can be measured with high reliability. Moreover, since it is such a simple method, it has excellent effects such as being able to automate the measurement system.

[Brief explanation of the drawing]

FIG. 1 shows a first embodiment of the present invention, and is a schematic configuration diagram showing an optical measurement system that implements the method of the present invention.

FIG. 2 is a configuration diagram of a channel selector used in the method of the present invention.

FIG. 3 is a front view of main parts showing the measurement state of the fiber to be measured.

FIG. 4 is a plan view of FIG. 3;

FIG. 5 is a sectional view taken along the line V-V in FIG. 3;

FIG. 6 shows a second embodiment of the present invention, and is a schematic configuration diagram showing an optical measurement system that implements the method of the present invention.

7 is a schematic configuration diagram of the optical measurement system in the case where the dummy fiber and the fiber to be measured are two cores in the optical measurement system of FIG. 6; FIG.

FIG. 8 shows a second embodiment of the present invention, and is a schematic configuration diagram of an optical measurement system in which an instruction/display mechanism is provided near a connecting portion.

FIG. 9 is a schematic configuration diagram illustrating a conventional optical fiber measurement method for optically measuring an optical fiber using OTDR.

FIG. 10 is a configuration diagram showing a channel selector used for batch measurement of conventional multicore fibers using OTDR.

[Explanation of symbols]

10 Optical reflectometer 11 Channel selector (optical path switching device) 12 Multicore dummy fiber 13 Butt jig (connection part) 13a V groove

Claims (1)

[Claims] 1. An OTDR and a plurality of dummy fibers are optically connected in a switchable manner by an optical path switching device having an adapter and an optical connector, and each of the plurality of dummy fibers is connected to a plurality of fibers at a connecting portion. The plurality of fibers to be measured are butt-connected to each of the plurality of fibers to be measured, and the test light from the OTDR is sequentially switched and emitted to each of the plurality of fibers to be measured via the plurality of dummy fibers by the optical path switching device. A method for measuring optical fibers at once, characterized by optically measuring fibers to be measured all at once.