JP3281676B2 - Screening method for mechanical strength of optical fiber connection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a standard clad diameter of 125 μm.
The present invention relates to a method for screening the mechanical strength of a silica glass optical fiber connection terminal before connection, and objectively and unifiedly inspects the mechanical strength of the connection terminal to improve the reliability of the test result. Not only can this be significantly improved, but also connection failures due to insufficient mechanical strength after the connection of the connection portion can be reduced as much as possible.

[0002]

2. Description of the Related Art A quartz glass optical fiber having a standard cladding diameter of 125 μm has a cross-sectional structure shown in FIG. 3, and has a core glass 1 and a cladding glass layer 2 surrounding the core glass. A coating layer 3 (UV resin, carbon, metal, or the like) is used, and each layer has a concentric structure. As a method for sequentially connecting the optical fibers, there are a fusion connection method in which the ends of the optical fibers are fused and connected, and a connector connection method in which the ends of the optical fibers are connected to each other by using a connector connected to the terminal of the optical fiber. However, in either case, the coating layer 3 at the end of the optical fiber must be removed. On the other hand, a silica glass optical fiber having a standard cladding diameter of 125 μm having the above-described cross-sectional structure has high mechanical strength against pulling and bending,
The glass core composed of the core glass 1 and the clad glass layer 2 surrounding the core glass 1 has extremely minute damage (0, 1) on its surface.
(μm or less), the mechanical strength thereof is extremely reduced (a few times) and becomes unusable. This is a well-known characteristic. Standard cladding diameter 125μ
If the surface of the glass core is scratched when the coating layer 3 is removed to connect the ends of the silica glass based optical fiber of m , even if the scratch is extremely fine, The mechanical strength of the connecting portion in the connected state is significantly reduced, and the finely damaged portion is deteriorated with time (the scratch grows naturally over a long period of time, and the mechanical strength is reduced). It is inevitable that the durability is impaired. After the coating layer 3 of the optical fiber f is removed in order to guarantee a certain or more mechanical strength of the connection part after the connection, an inspection (screening) of the mechanical strength of the glass core of the terminal part is performed. In this inspection, the tip of the glass core g having a predetermined length exposed from the optical fiber f is pushed sideways with a fingertip to apply a bend, and the tip is rotated 360 degrees in this state to thereby obtain a predetermined size in the direction of 360 degrees. (See FIG. 4). If the terminal portion of the glass core g exposed by this inspection has a predetermined damage or more, the terminal portion is broken at the damaged portion, so that the damaged portion can be found in advance before connection, and the damaged portion can be removed in advance. If the terminal is not broken in this inspection, the terminal is passed and the terminal is used for connection. Since this inspection method depends on the intuition of a skilled worker, the inspection work itself is not efficient, the uniformity of the inspection method, the objectivity and accuracy of the inspection result are poor, and Required bending cannot be applied to the tip of the glass core g. Therefore, the reliability of the inspection result is poor, and the occurrence of connection failure due to insufficient mechanical strength of the connection portion is sufficiently reduced. The problem remains that you can't. Optical fiber
Fix the tip of the glass core after removing the coating on the
After applying a predetermined tensile force to the end of the rear optical fiber,
It is also known to conduct a strength test (Japanese Patent Laid-Open No. 3-54).
No. 433) discloses a quartz cladding having a standard cladding diameter of 125 μm.
Applying this to screening of lath-based optical fibers
Sometimes, a small scratch is made or covered for the test.
If a fine scratch is given during the removal operation,
There is a possibility that the beam will deteriorate over time.

[0003]

[0008] The present invention is to solve the above conventional problems and its object, in order that a standard
After removing the coating of the silica glass based optical fiber having a cladding diameter of 125 μm, the strength of the end of the glass core is inspected. Uniform, accurate,
It is an object of the present invention to be able to perform the work efficiently.

[0004]

Means taken to solve the above-mentioned problems are constituted by the following elements (a) and (b). (A) Fixing the tip of the glass core after removing the coating of the silica glass optical fiber having a standard cladding diameter of 125 μm to a jig,
After that, 1kgf per optical fiber at the end
(3) Applying a tensile force of 3 seconds to perform a strength test. (B) After removing the tip fixed to the jig of the core, provide the connection.

[0005]

When a simple pulling force is applied to the optical fiber with the end of the glass core exposed by removing the coating fixed to the jig, the glass core is equally tensioned all around its circumference, and Since the magnitude of the simple tension can be precisely adjusted mechanically, the inspection is performed uniformly, objectively, quantitatively and accurately. Predetermined tension is not applied to the tip fixed to the jig,
Although the surface is likely to be damaged due to contact with the jig, this part is cut off, the cut surface is polished, and the connection is provided, so the part whose strength is not confirmed by the above inspection is connected. It is not offered at all. Then, a quartz glass optical fiber having a standard cladding diameter of 125 μm is used.
In the case of Iva, the fixing force by the above jig is large and
As the fixing time is longer, the coating of the fixed part is
Separation occurs, causing microscopic scratches on the glass core in this area
Is more likely to occur . However, optical tension is applied for testing.
Aiba per 1 and 1kgf, time to add the tension of this
For 3 seconds, the pressing force of the fixed part is limited.
And the time for pressing is short,
Local delamination of optical fiber coating, minute scratches on glass core
The test reliably prevents the occurrence of micro-scratches.
Of the test is therefore prevented.
Is guaranteed to cause deterioration over time due to small scratches
Is prevented. In addition, in coating removal work,
If a fine scratch is made, keep the tension of 1kgf or more
During this time, the fine scratches expand during this time and pull
If it does not break from this part in the test
In addition, due to the enlargement of these fine scratches,
Deterioration over time is promoted, but the tension is 1 kgf,
By limiting the time for applying tension to 3 seconds, the above described
Size is suppressed as much as possible, and
Time degradation is suppressed as much as possible.

[0006]

First, the above inspection was carried out for a plurality of standard clad diameters of 12 or more.
An example in which a 5 μm quartz glass optical fiber is simultaneously performed will be described with reference to FIG. The jig 10 includes a base 11 and a holding plate 12. The upper surface of the base 11 is coated with hard plastic, and a hard rubber layer 13 is laminated on the lower surface (holding surface) of the holding plate 12. Base 11
Is supported movably in the direction of arrow YY by a rail L fixed to the upper surface of the work table T. A tension device 30 provided on a work table T is attached to a base 11 of the jig 10. This tension device may be any device having a tension adjusting function and a tension display function. A plurality of standard clad diameter 125 μm silica glass optical fibers f are coated at their ends by removing the coating on the ends.
Is exposed by a predetermined length, and this glass core g is
The holding plate 12 is aligned with the upper surface of the
The tip of the glass core g is fixed to the base 11 by being tightened by an appropriate tightening mechanism using a nut or the like. Since the tip of the glass core g is gripped by the hard plastic layer on the upper surface of the base 11 and the hard rubber layer 13 on the lower surface of the holding plate 12, the tip of the glass core is softly and strongly gripped by the jig. After fixing the tip of the glass core g to the jig 10, the main body of the optical fiber f is clamped in the vicinity of the jig 10.
Fixed to. The clamp 20 may be any clamp as long as it can firmly fix the main body portions of all the optical fibers f in a parallel state. In this example, like the jig 10, the clamp 20 is provided with a support table 21 having a flat upper surface. A clamping device for tightening the holding plate 22 with an appropriate tightening mechanism such as a bolt or a nut is employed. The fastening force for this fixation is
Test tension (1kgf per fiber per fiber)
This is the limit required to keep the optical fiber f fixed.
You. The optical fiber f of this embodiment has a standard cladding diameter of 125.
μm, quartz glass fiber, test tension is 1
kgf. In this example, since there are four optical fibers, the pulling force of the pulling device 30 is set to 4 kgf.
The tensile force F by operating the tensioning device Ru tensile jig 10 for 3 seconds while checking by the display mechanism. At this time, a simple pulling force is evenly applied to each optical fiber f, and a fiber having a damaged surface is broken. Optical fiber f that did not break
With regard to (2), the tip of the glass core held by the jig 10 is cut off, and the cut surface is polished and provided for connection. When used for connector connection, before fixing to the jig 10, an optical fiber is passed through a ferrule to which an adhesive has been applied in advance, the glass core is made to protrude from the ferrule, and the tip of the glass core is fixed to the jig. After screening, the tip of the glass core that has not been broken may be cut off, fixed to a ferrule as it is, and then the end face of the glass core may be polished. This embodiment is an example in which the tip of a glass core is fixed to a jig by a clamp mechanism. A plate-like replacement part is detachably fixed to the upper surface of a base 11 of the jig, and the replacement part is fixed. The tip of the glass core may be bonded and fixed to the upper surface using a so-called instant adhesive. In this case, the tip fixed to the jig is cut off from the glass core g and is left on the replacement part. Therefore, when there is no room for attaching a new glass core to the upper surface of the replacement part, the replacement part is replaced. do it. Further, when screening the optical fibers one by one, as shown in FIG.
The tip of the glass core g is attached to the simple fixing plate 40 with the instant adhesive 4
1 and apply a tension of 1 kgf while checking the tension by an appropriate tension means. In this case, a person may pull the tension via the tension measuring means.

[0007]

According to the method of the present invention, the standard cladding diameter
Since the glass core of a 125 μm silica glass optical fiber can be passed through a ferrule and fixed to the ferrule for post-screening. As a result, the deterioration of the mechanical strength of the connection part due to the above is also screened, and the part of the exposed glass core accommodated in the ferrule is also screened, so that the reliability of the strength of the connection part is further enhanced. This effect is applicable not only to the connector connection but also to all connection methods in which a part of the exposed glass core is housed in the housing and the strength of this part cannot be confirmed outside. And
In addition, the test tension is limited to 1 kgf per optical fiber.
Limit the tightening force for fixing
By limiting the application time to 3 seconds, the coating of the fixed part
It is confirmed that local peeling has occurred and micro scratches have occurred in the area.
Indeed, avoid the deterioration of the glass core over time due to the minute scratches.
Ru can be downright prevention. Furthermore, coating removal work
Screening of micro scratches on glass core
And the aging will promote deterioration over time.
Can also be avoided as much as possible.

[Brief description of the drawings]

FIG. 1 is a perspective view of a first embodiment of the present invention.

FIG. 2 is a perspective view of a second embodiment.

FIG. 3 is a cross-sectional view of a silica glass optical fiber having a standard cladding diameter of 125 μm.

FIG. 4 is an explanatory diagram of a conventional screening method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Jig 20 ... Clamping device 30 ... Tensioning device f ... Optical fiber of silica glass system with standard cladding diameter 125m g ... Glass core

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 3/00 G01M 11/00 G02B 6/00 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. A tip of the glass core after coating removal of the optical fiber of silica glass-based standard cladding diameter 125μm fixed to a jig, then 1 to the terminal portion of the Resona per one optical fiber
A mechanical strength screening method for an optical fiber connection portion, in which a strength test is performed by applying a tensile force of kgf for 3 seconds, and a tip fixed to the glass core jig is removed and polished for connection.