JPS59160113A - Melt sticking and connecting method of optical fiber using image pickup device - Google Patents

Abstract

PURPOSE:To reduce the loss of connection and to improve connecting efficiency by melt sticking and connecting the optical fibers to be connected while adjusting their position by making use of the light emitted by the fibers and the light intensity during melt sticking and heating. CONSTITUTION:When optical fibers 1, 1' to be connected arrive at a heating part 10, the clads and cores thereof are softened by heat and at the same time, light is emitted therefrom at the different light intensities. The positions in the directions (x) and (y) of the cores of fibers 1, 1' from the orthogonally intersecting directions (x), (y), the distance between the end faces of the opposed fibers 1, 1' and the luminous intensity in the juncture of the fibers 1, 1' are simultaneously measured by an image pickup device consisting of an objective lens system 12, an image sensor 13, an image sensor driving device 14 and an image processor 15. The positions in the (x), (y) directions of the image pickup direction in the right angled two directions of a control device 16 are controlled by the signal from said image pickup device, by which the axial alignment of the cores of the fibers 1, 1' is accomplished; in addition, the extent of the movement in the remaining (z) direction is adjusted and further the current in a gas discharge circuit 8 is adjusted, by which the heating temp. is maintained constant.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of efficiently connecting optical fibers with low loss using an imaging device.

When performing fusion splicing of optical fibers, align the cores of the optical fibers, set the distance between the end faces of the optical fibers, and heat the end faces of the optical fibers at the softening point temperature of the optical fiber material. It is necessary to press the Conventional core alignment methods for this type of optical fiber include the following.

(1) Figure 1 shows a method for aligning the core of an optical fiber called the power monitoring method. In this method, a light source 2 and a receiver 3 are placed on the connected fibers 1 and 1', and the cores of the connected fibers 1 and 1' are aligned in the X and y directions so that the transmitted power at the connection point is maximized. It's a method. However, this method requires a large number of personnel and equipment, and has the drawback of poor work efficiency, since the work for connection is distributed over three locations: the light source, the connection point, and the light receiving point.

(2) References 1981 General National Conference of the Institute of Electronics and Communication Engineers qs
4J single-mode optical fiber core alignment method IP, 4-
181, there is a method that utilizes the fluorescence phenomenon caused by ultraviolet excitation of a Ge-doped optical fiber. However, this method is limited to the case of a core containing a dopant and requires a laser light source in the ultraviolet region.
There was a drawback that C was large.

(8) Literature Journal of the Institute of Electronics and Communication Engineers “82/5 Vol.
.

J65-B, j6.5 P, 662 As seen in ``Single mode optical fiber connection method without monitor'', the optical fiber is soaked in a liquid with the same refractive index as Clara 1, and the core is detected with a phase contrast microscope. There is a method to align the cores. However, this method had the drawback of not being able to detect the core in air.

(4) There is a method of detecting the core of an optical fiber in the air using a differential interference microscope and aligning the core. However, this method has the disadvantage that it requires a special device called a differential interference microscope, and that the design of the optical fiber alignment fine movement C1 is limited by the size of the microscope body.

By the way, the distance between the end faces of the optical fibers to be connected (1) can be carried out manually without visually observing the distance between the end faces of the optical fibers using a marker installed in a microscope or by the operator, or by manually connecting the end faces of the opposite optical fibers to be connected. Once the contact is made, it is pulled a certain distance using a micro-adjustment mechanism such as a micrometer. Since it is done manually, the work efficiency is low and the work quality deteriorates depending on the level of skill.

Alternatively, as shown in FIG. 2, there is a method of setting the difference between the end faces by abutting the optical fiber 1 to be connected against an abutment plate 4 having a constant thickness. However, this method (1 year old) requires a special attack to move the abutment plate 4, and dust attached to both sides of the abutment plate 4 may cause damage to the connected optical fibers 1, 1.
It has the disadvantage that it adheres to the connection end face of the 100mm, increasing the connection loss.

In addition, the distance between the end faces is set to a constant value to ensure that the fibers to be connected are pushed in, but the distance between the end faces changes depending on the roughness of the end face and the fusion heating temperature, so the actual amount of push-in changes. However, there were drawbacks such as connection failures and poor connection quality.

On the other hand, the heating temperature of the end face of the optical fiber to be spliced is set to a constant value based on the softening point temperature of the optical fiber material, end face spacing, humidity to reduce splice loss, etc.; however, in the case of gas discharge, fusion splicing When melting (hJ) (fiber scatters to the discharge electrode and the heating temperature changes, there was a drawback that the setting of the heating equipment had to be changed several times.

In order to eliminate these drawbacks, the present invention uses an imaging device to detect the image and light intensity emitted by the optical fiber to be connected during fusion heating using a gas discharge device or a CO2 laser device, and determines the core axis alignment and pushing amount. The optical fiber is fusion spliced while adjusting one or more of the clause 1iid and the fusion heating temperature of the optical fiber connection part,
The purpose is to reduce connection loss by 4 degrees, reduce connection failures, and improve connection efficiency. The present invention will be explained in detail below with reference to the drawings.

FIG. 3 is a diagram showing an embodiment of the present invention, in which 1 and 1' are optical fibers for branch connection, 5 and 5' are electric motors, 6° and 6' are fine movement mechanisms, and 7 and 7' are optical fiber orientation devices. 8 is a gas discharge circuit, 9 and 9' are discharge electrodes, 10 is a heating section, 11 is a filter, 12 is an objective lens system, 13 is an image sensor, 14
15 is an image sensor driving device, 15 is an image processing device, and 16 is an image sensor driving device.
is a control device, and 17° and 17' is an electric motor drive section.

To operate this, a fine movement mechanism 6, 6' driven by an electric motor 5, 5' moves the optical fiber fixing table 7, 7' in the x, y, and Z directions to remove and cut the fiber. The completed optical fibers 1 and 1' to be connected are fixed facing each other. Optical fiber fine movement mechanism system 5.5', 6°6', 7, 7'
When the unconnected optical fibers 1 and 1' are sent in the Z direction, the spliced part of the spliced optical fiber is driven by the gas discharge circuit 8, and reaches the heating part 10 generated between the discharge electrodes 9 and 9'. The cladding portion and core portion of the connected optical fiber 1.1' are softened by heat and at the same time emit light with different light intensities. At this time, the objective lens system 12
and image sensor 13 and image sensor drive device] 4t
and the image processing device 15, the positions of the cores of the optical fibers 1 and 1' in the X direction and the
, 1' and the distance between the end faces of connected optical fibers 1, 1'
At the same time, the emission intensity of the connection part, that is, the heating temperature, is detected. FIG. 4 shows a side view of this imaging device. The electric motor is driven by the control device]6 based on the signal from this imaging device.

17', electric motors 5, 5', fine movement mechanisms 6, 6
', σ in two perpendicular directions via the optical fiber fixing bases 7 and 7'
) By adjusting the positions of the optical fibers 1 and 1' to be connected in the X and y directions using the imaging system, the optical fibers 1 and 1' can be
After aligning the cores, the remaining movement in the Z direction,
That is, the heating temperature can be kept constant by adjusting the pushing amount of the connected optical fibers 1 and 1 and further by adjusting the current of the gas discharge circuit 8. Therefore, for opening the connected optical fiber l, there is no need for a lighting device, and since the heating temperature is constant, that is, the light J6i degrees emitted by the optical fiber is constant, there is no need to adjust the brightness of the light source. do not have. Furthermore, even if the molten fiber is scattered and attached to the gas discharge electrodes 9, 9' during fusion splicing, the intensity of the light is directly measured, so that the heating humidity can be adjusted to a constant level. Note that the light generated from the gas discharge itself has a lower light intensity than the light generated by heating the optical fiber, so there is no need to pose a problem.

In this example, a gas discharge device was used as the heating device, but a CO2 laser device (ff) may also be used. Even if the characteristics of the heating device system including the laser device change, the humidity of the optical fiber can be directly detected. Therefore, it can be modified and the heating conditions can be kept constant.

Also, the laser light and the light generated by heating the optical fiber are
They can be distinguished by the wavelength of light. Therefore, the image to be detected can be considered similar to a gas discharge.

In this example, ]P production system 11, ], 2, 1
3.

14 were used, but as shown in Figure 5, 2
Mirrors 18, 1.8' and 1 half mirror 19
By introducing an optical system using
For one of the two directions, the imaging systems 11 and 12
, 13 and 14 can be omitted.

In addition, this example describes a case in which eight factors, including core alignment, push-in position, and heating humidity, of the optical fiber to be connected are adjusted simultaneously; however, core alignment is required for silk mode optical fibers. However, in the case of multimode optical fibers, core alignment may not be necessary. However, even in the case of multimode optical fibers, core position detection can be used to check the quality of work.

In this embodiment, if there is a problem that the operating speed of the finely moving feed threads 5, 5', 6, 6', 7, 7' of the optical fibers 1, 1' to be spliced is slow compared to the fusion splicing speed. This can be solved by setting heating conditions such as heating time, heating intermittent time, and heating temperature.

As explained above, the optical fiber fusion splicing method of the present invention utilizes the light emitted by heating the optical fiber, so it has the advantage of simplifying the configuration of the splicing device, such as eliminating the need for an optical fiber illumination device. Compared to illumination methods using transmitted light or reflected light, this method has the advantage that there are fewer negative effects such as reduced resolution due to the lens effect of connected optical fibers.

In addition, the fundamentally important connection conditions such as the alignment of the core of the optical fiber to be connected, the amount of push-in, and the heating temperature of the connection part are adjusted, so optical fibers with low loss, few connection failures, and high work efficiency can be created. It has the advantage of being able to connect.

Therefore, it will greatly contribute to the practical application of communication systems using optical fiber cables.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of a method for aligning the cores of optical fibers to be connected using a conventional power monitor. Figure 2 is an explanatory diagram of a method for setting the distance between the end faces of optical fibers using an abutment plate. 1 is a side view of the imaging device for detecting the core of the optical fiber to be connected in FIG. 3, and FIG. 5 is one system of the imaging system shown in FIG. 4. FIG. 3 is a diagram showing a specific example in which an optical system is used instead of the optical system. DESCRIPTION OF SYMBOLS 1... Optical fiber to be connected, 2... Light source, 3... Light receiver, 4... Abutment plate, 5, 5'... Electric motor,
6, 6'... Fine movement mechanism, 7, 7'... Optical fiber fixing base, 8... Gas discharge circuit, 9, 9'... Discharge electrode, 10... Heating section, 11...・Filter, 12...
Objective lens system, 13... Image sensor, ]4...
Image sensor driving device, 15... Image processing device, 1
6.16'...Restriction 1 device 1'? , l 7 , 17'
...Electric morph drive unit, 18.18'...Mirror,
19...Half mirror-0 Patent applicant Nippon Telegraph and Telephone Public Corporation Figure 2 Figure 3 Figure 4 Figure 5 ■i L-ch

Claims (1)

[Claims] 1. In a method of fusion splicing optical fibers by applying rlb and abutting the end faces of opposing optical fibers to be connected, a gas discharge device or a CO2 laser device is used to connect the cladding of the optical fiber to the cladding of the optical fiber during fusion heating splicing. Utilizing the phenomenon that the cores emit light with different light intensities, an imaging device is used to detect the core position of the optical fibers to be connected, the distance between the end faces, or the heating temperature. An imaging device characterized in that optical fibers are fusion spliced while adjusting one or more of the following: adjustment of the axis alignment of the optical fiber, adjustment of the pushing source, and adjustment of the fusion heating temperature of the optical fiber and bar connection portion. Optical fiber fusion splicing method used.