JPH0652331B2 - Optical fiber alignment determination method - Google Patents

Description

The present invention relates to an optical fiber axis alignment determination method used when connecting optical fibers to each other.

"Prior art" When a pair of optical fibers, whether single-core or multi-core, are fusion-spliced in the longitudinal direction, the optical fiber ends are axially aligned with each other before the fusion, and the axial alignment state is obtained. The suitability of is observed by a microscope and checked.

For example, in the case of a multi-fiber optical fiber called a tape type, as known from Japanese Patent Laid-Open No. 59-74520, the first
Predetermined observation is carried out as shown in FIGS.

In FIGS. 1 and 2, 1A and 1B are multicore coated optical fibers, 2A and 2B are coated optical fibers 1A and 1B, and 3A,
3A ..., 3B, 3B ... are each coating layer 2A,
Optical fiber end exposed from end 2B, 4A, 4A ……, 4B,
4B ... is the end face of these optical fibers.

5A and 5B are optical fiber mounting bases having a plurality of parallel V grooves on the upper surface, and 6 is a vertically movable end plate interposed between adjacent portions of the optical fiber mounting bases 5A and 5B.

The end plate 6 has a ridge line portion 7 at its tip and the ridge line portion 7
From the optical fiber mounting table 5A, 5B to the descending slope (gradient
45 °) mirror surface portions 8A and 8B are formed.

The end plate 6 also serves as an abutting plate for setting the optical fiber end face spacing.

Reference numeral 9 is a known microscope, and only the objective lens side is shown in FIG.

In FIG. 1 and FIG. 2, the optical fiber mounting bases 5A, 3A, 3A ..., 3B, 3B ... of the coated optical fibers 1A, 1B are arranged so that the pair of optical fiber ends 3A, 3A. 5B
Placed on top of each fiber end face 4A, 4A ..., 4B, 4B ...
By abutting .. on both sides of the end plate 6, the distance between these end faces is set.

Further, thereafter, the pair of optical fiber ends 3A, 3B, 3A, 3B ... Are axially aligned by a predetermined centering operation, and the observation that should determine the appropriateness of the axial alignment is performed by observing the end plate 6 and the microscope 9. Via the following:

That is, in this observation, both mirror surface portions 8A, 8B of the mirror plate 6 are interposed between the optical fiber end surfaces 4A, 4B, 4A, 4B ... And the optical fiber end surfaces 4A, 4A. , 4B, 4B ...
.. (hereinafter referred to as end face images) a, a ..., B, b ... Are projected.

The end face images a, a ..., Which are projected on both mirror surface portions 8A, 8B
b, b ... Are located at a position separated by 1 and 1'from the ridge line portion 7.

Since the mirror surfaces 8A and 8B are inclined, the distances l and l'become smaller when the optical fiber end surfaces 4A, 4A ..., 4B, 4B ... are at a high position, and conversely, the optical fiber end surfaces 4A, 4A ...,
It becomes larger when 4B, 4B ... is in the lower position.

By the way, when l = 1 'for both distances,
The pair of optical fiber ends 3A, 3B, 3A, 3B ........ It can be said that there is no vertical axis misalignment with each other, but when l <l 'or l>l', the optical fiber ends 3A, 3B, 3A. , 3B ... It can be said that there is vertical misalignment due to the height difference between them.

Therefore, by observing through the microscope 9 whether or not l = 1 ', it is possible to determine the suitability of the axial alignment state in the vertical direction (vertical direction).

The suitability of the horizontal alignment state in FIGS. 1 and 2 is
After the end plate 6 is withdrawn from between the optical fiber end faces 4A, 4B, 4A, 4B ..., when the next end face interval (a minute interval before the start of fusion) is set, it is judged through a microscope observing means or the like. It

[Problems to be Solved by the Invention] In the case of the above-described conventional technique, the optical fiber axis alignment state in the vertical direction can be observed through the mirror surface portions 8A and 8B of the mirror plate 6, and the observation accuracy is as follows. There is a problem.

That is, since the depth of focus of the microscope 9 is not sufficient, the end face images a, a ...
... becomes blurred, and conversely, the end face images a, a ..., b, b ...
When focusing on ..., the ridge line portion 9 is blurred, and as a result, the distances l and l'based on the ridge line portion 9 cannot be accurately measured, and the observation accuracy is reduced.

Besides, in the conventional technique, only the vertical axis observation can be performed, and the horizontal axis observation work is separately required.
Overall, the observation work lacks rationality.

In view of the above-mentioned problems of the prior art, the present invention aims to provide a method capable of rationally performing this type of observation work and accurately determining whether or not the optical fibers are properly aligned with each other.

"Means for Solving Problems" The optical fiber axis alignment determining method according to the present invention is characterized by the following means in order to achieve the intended purpose. That is, two optical fiber mounting bases that are opposed to each other while keeping a space adjacent to each other on a straight line, and an end plate having two mirror surface portions that descend and incline from the ridge line portion at the tip to both sides of the ridge line portion are prepared. , An end plate of an optical fiber is placed between the adjacent parts of the optical fiber mounting base, and the end parts of the pair of optical fibers are arranged to face each other on the optical fiber mounting base. The optical fiber end surface images projected on both mirror surface portions are brought into contact with the ridge line portion of the mirror plate, and in this projected state, the paired optical fiber end surface images make the ridge line portion of the mirror plate an axis of symmetry. When the pair of optical fibers are in line symmetry, the axial state of the pair of optical fibers is suitable, and when the pair of optical fiber end face images do not have the above line symmetry,
The feature is that the alignment state of the optical fibers forming a pair is rejected.

"Example" An example of the optical fiber axis alignment determination method according to the present invention,
This will be described with reference to FIGS. 3 to 5.

3 and 4, 1A and 1B are multi-fiber type coated optical fibers, 2A and 2B are coating layers of the coated optical fibers 1A and 1B, 3A,
3A …… and 3B, 3B …… are the optical fiber ends, 4A, 4A ……
And 4B, 4B ... are the end faces of these optical fibers.

5A and 5B are optical fiber mounting bases, 6 is a mirror plate having a ridge line portion 7 and mirror surface portions 8A and 8B at its tip, and 9 is a microscope.

The coated optical fibers 1A and 1B, the observing device, and the like in FIGS. 3 and 4 are the same as those described in FIGS. 1 and 2, and therefore detailed description thereof will be omitted.

When observing the alignment state of the optical fibers by the method of the present invention, the optical fiber end portions 3A, 3B, 3A, 3B ... which are paired on the respective optical fiber mounting bases 5A, 5B are mutually in the same manner as the above-mentioned example. They are set facing each other, and the optical fiber end faces 4A, 4B, 4A, 4B ......
, That is, the end face images a, a ..., B, b ... Are projected on the mirror surface portions 8A, 8B of the mirror plate 6.

In the method of the present invention, in the above, the end face images a, a ...
The mirror plate 6 and the optical fiber mounting bases 5A and 5B are positioned relative to each other so that b ... Contact the ridge line portion 7 of the mirror plate 6.

In such a case, the end surface image a projected on the mirror surface portions 8A and 8B,
a ..., b, b ... have a shape such that a part of a circle is cut by the ridge portion 7, and a pair of end face images a,
b, a, b ... Adjacent to the left and right with the ridge 7 as a boundary.

In this case, the pair of end face images a, b, a, b ... Are shown in FIG.
(B) Any of the states illustrated in (b) and (c), or (b) in the figure
(C) becomes a composite state.

In the case of FIG. 5 (a), the end face images a and b have precise line symmetry with the ridge line portion 7 as the axis of symmetry, and in such a state, the paired optical fiber end portions 3A and 3B are It can be said that there is no axial misalignment in either the vertical or horizontal direction.

In the case of FIG. 5B, the optical fiber end surface 4A which is the real image of the end surface image a is low, and the optical fiber end surface 4B which is the real image of the end surface image b.
Is at a high position and is in such a state that the optical fiber end surface 4A,
It can be said that 4B is vertically off-axis by the off-axis amount m.

In the case of FIG. 5C, the optical fiber end faces 4A, 4B, which are the real images of the end face images a, b, are relatively axially offset along the ridge line portion 7. Therefore, in such a state, the optical fibers are edge
It can be said that 3A and 3B are axially offset by the axial offset amount n.

In the method of the present invention, such a state is observed by the microscope 9 and it is checked whether or not the axial deviation amounts m and n occur individually or in combination.

Since these axial deviation amounts m and n all appear on the ridge line portion 7, when confirming the presence or absence thereof, it suffices to focus on the ridge line portion 7 and observe with a microscope. In addition to being able to observe precisely, vertical and horizontal axis alignment observations can be performed simultaneously.

In the method of the present invention, an appropriate judgment result was obtained.
The optical fibers of (a) are fusion-spliced to each other via a well-known fusion splicing means.

That is, the end plate 6 and the microscope 9 are connected to each optical fiber end 3
After leaving the vicinity of A, 3A ..., 3B, 3B ..., these optical fiber ends 3A, 3A ..
Discharge heat is supplied to 3B, 3B, ..., and the pair of optical fiber end faces 4A, 4A ..., 4B, 4B are butted against each other and are fusion-bonded.

In the method of the present invention, the judgment result is inappropriate.
The optical fibers of (c) are also spliced in the same manner as described above, after the axial deviation is corrected with reference to the axial deviation measured as described above.

As is obvious, the connection loss between the optical fibers thus fusion-spliced has a small transmission loss.

The method of the present invention can be used not only for the alignment of the illustrated multi-fiber optical fibers but also for the alignment of the single-fiber optical fibers.

"Effects of the Invention" With the optical fiber axis alignment determination method according to the present invention, the following effects are obtained.

(1) At the time of the microscope in determining the alignment of the optical fiber, it is only necessary to focus the microscope on the ridgeline portion of the end of the end plate, so that the observation work of the optical fiber end face image through the microscope can be simplified.

(2) When judging whether the optical fiber is in the proper axial alignment, it is possible to judge in two directions (vertical direction, horizontal direction) at the same time by observing from one direction, so this kind of work is rationalized. can do.

(3) When determining the optical fiber axial alignment state, it is only necessary to check whether or not the pair of optical fiber end face images are line-symmetrical with the ridge line portion at the end of the end plate as the axis of symmetry. That is, when determining the alignment of the optical fibers, it is not necessary to measure the position of each optical fiber end face image (distance from the reference point), but whether the pair of optical fiber end face images match each other on the symmetry axis. Since it is only necessary to look at, it is difficult to make a mistake in the judgment. Therefore, not only the judgment itself can be performed easily, but also a highly reliable judgment result can be obtained.

(4) The optical fiber end parts that were confirmed to be suitable for the axial alignment were fused together by conventional means to form an optical fiber connection part with a small connection loss. Mutually, after the misalignment is corrected,
Since the optical fiber splicing portion is fusion-spliced in the same manner as described above to form the optical fiber splicing portion with a small connection loss, the optical fiber fusion splicing portion having good transmission characteristics can be obtained.

[Brief description of drawings]

1 and 2 are a plan view and a front view schematically showing a conventional method, and FIGS. 3 and 4 are a plan view and a front view schematically showing one embodiment of the method of the present invention. (B) and (C) are explanatory views illustrating various states of the optical fiber end face image in the method of the present invention. 1A, 1B …… Coating optical fiber 2A, 2B …… Coating layer 3A, 3B …… Optical fiber end 4A, 4B …… Optical fiber end face 5A, 5B …… Optical fiber mounting table 6 …… End plate 7 …… End plate Ridges 8A, 8B …… Mirror surface of mirror plate 9 …… Microscope a, b …… Optical fiber end face image m, n …… Axis deviation

Front page continued (72) Akihiro Otake, 6th Hachiman Kaigan Dori, Ichihara City, Chiba Prefecture Furukawa Electric Co., Ltd. Chiba Electric Wire Works (72) Inventor, Michito Matsumoto, Tokai Village, Naka County, Ibaraki Prefecture 162 Address, Nippon Telegraph and Telephone Corporation, Ibaraki Research Institute of Telecommunications (56) References JP 59-74520 (JP, A) JP 51-133044 JP, A)

Claims (1)

[Claims] 1. A pair of optical fiber mounting bases that are opposed to each other while keeping a space adjacent to each other on a straight line, and a mirror plate having two mirror surface portions that are inclined downward from a ridge line portion at the tip to both sides of the ridge line portion. Prepare and interpose an end plate between the adjacent portions of the optical fiber mounting table, and arrange the end portions of the paired optical fibers on each optical fiber mounting table so as to face each other, and to dispose the end surfaces of these optical fibers. The optical fiber end surface images projected on both mirror surface portions of the mirror plate are brought into contact with the ridge line portion of the mirror plate, and in this projected state, the paired optical fiber end surface images are aligned on the ridge line portion of the mirror plate. When the axis of symmetry is used for line symmetry, the paired optical fibers are properly aligned, and when the end face image of the pair of optical fibers is not the above-mentioned line symmetry,
An optical fiber axial alignment determination method for rejecting the axial alignment state of a pair of optical fibers.