JPS59136708A - Automatic connecting device for optical fiber - Google Patents

Abstract

PURPOSE:To realize high-precision alignment by observing butting end parts of optical fibers in two directions with transmission lighting, and moving those two optical fibers automatically and relatively by picture processing from contour parts of core parts so that the core parts are aligned to each other. CONSTITUTION:A fixed base 11 and a movable base 12 which face each other are provided with metallic pressers 15 for fixing the optical fibers 13 and 14 respectively; and those metallic pressers 15 are freely slidable in the facing direction of the butting end parts of the optical fibers 13 and 14 and in a direction perpendicular to said facing direction. Movements in those two directions are carried out by two driving motors. A couple of discharge electrode 18 for connecting the butting end parts of the two optical fibers 13 and 14 by welding are provided and a couple of light guides 20 and 21 connected to a light source 19 are positioned so that their projection end parts are in those two directions.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical 7-eye 2-bar fusion splicing device designed to quickly and automatically perform permanent connections with extremely high precision.

Conventional methods for connecting optical fibers include a method using a connector that can be separated at will even after connection, and a method using a permanent connection (splicing) that cannot be separated after connection. be. in general,
It is known that connectors have a greater connection loss than permanent connections due to reflection loss at the end face of the optical fiber, and these are used appropriately depending on the conditions of use.

Therefore, when permanently connecting communication optical fibers such as submarine optical cables, which are often used as long-distance transmission lines, fusion splicing is used because there is less risk of deterioration over time. Normally, optical fibers have a protective and reinforcing coating layer formed around them, and the presence of this coating layer causes various problems when optical fibers are fusion spliced to each other. The coating layer was removed to expose the optical fiber to the outside, and the end faces of the fibers and the fibers were coaxially abutted against each other and then fusion spliced by electrical discharge heating. In this case, if the core part that participates in light transmission is eccentric with respect to the optical fiber wire, it is impossible to achieve the best connection state simply by positioning the optical fiber wire coaxially. This tendency is particularly noticeable in single mode optical fibers with small core diameters. For this reason, the general method is to pass light from one optical fiber to the other and adjust the relative position of the butt ends of the two optical fibers so that the amount of light received by the other optical fiber is maximized. It has been adopted. However, in cases where repeaters, etc. are already connected to the optical fiber, such as submarine optical cables, it is fundamentally impossible to employ all of the above methods, and furthermore, the submarine optical cables must be connected at sea. Because of this, there were many restrictions due to ship vibrations, ocean weather, etc., and there was a drawback that a good permanent connection could not be completely separated.

Based on this knowledge, the present invention focuses on the fact that the entire position of the core can be accurately determined when observing an optical fiber under transparent or super-illumination, and it is possible to permanently connect optical fibers in a short time. The purpose is to provide a device that can perform automatic processing with high precision.

The structure of the automatic optical fiber splicing device of the present invention that achieves this object is such that the butt ends of two optical fibers that are permanently connected are connected in opposite directions, and the two optical fibers are connected at right angles to the opposite directions. a positioning drive device capable of relative movement in a direction; a fusion device that fully heats and fuses the butt ends of the two optical fibers; an illumination device that transmits illumination of the butt ends of the two optical fibers; a microscope for observing the abutting ends of the two optical fibers from the two directions using transmitted illumination light from an illumination device; and a microscope for observing the butt ends of the two optical fibers from the two directions using transmitted illumination light from an illumination device; an image processing device for detecting a positional deviation of the core portion of the image processing device, and an operation of the positioning drive device so that the core portions of the two optical 7-eyepers are coaxial based on the detection signal from the image processing device. It consists of a control device that controls the

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an automatic optical fiber connection device according to the present invention will be described in detail below with reference to FIGS. 1 to 3. As shown in FIG. 1, which shows the connection work state according to this embodiment, there are nine optical fibers 13, 14 ffi between the fixed table 11 and the movable table (positioning drive device) 12 which face each other.
A presser metal fitting 15 for fixing is provided. The presser metal fitting 15 of the movable base 12 is slidable in two directions, one in which the butt ends of the optical fibers 13 and 14 face each other and two directions perpendicular to the opposite direction. As shown in FIG. 2, which represents the system, movement in the two directions is carried out by two drive motors 16 built into the movable table 12.
The movement in the opposite direction n1 is also carried out by the operation of the drive 54x (not shown). A conventional drive mechanism for the presser metal fitting 15 of the movable base 12 can be used as is, and the fixed base 11 may have the same structure as the movable base 12, but in short, two is sufficient. A pair of discharge electrodes (fusion splicing device) 18 are installed between the fixed base 11 and the movable base 12, facing each other across the butt ends of the optical fibers 13 and 14, and for fusion splicing these parts. Furthermore, the light emitting ends of a pair of light guides 20, 21 connected to the light source 19 are positioned so as to face the two directions, respectively.

A television camera 2 is mounted on a pair of microscopic mirrors 22 and 23 which are placed between the butt ends of the optical fibers 13 and 14 and are opposed to the light emitting ends of the pair of light guides 20 and 21.
4 is attached, so that the television camera 24 is now in a condition to observe the abutting ends of the optical fibers 13 and 14 from the two directions using the transmitted illumination light from the lie 1 guides 20 and 21. In this example, #i microscope 22
．． A pair of light guides 20 and 23 and a television camera 24 are provided, but as shown in FIG. The opposing reflections @ 25 can also be installed at an angle so that one of the microscopes 22 observes the abutting ends of the optical fibers 13, 14 from two different directions. The output from the television camera 24 is input to an image processing device 26, which is connected to two optical fibers 13.1.
The position of the core portion along the two directions of the optical fiber 13.4 is electrically detected and calculated.
Since there is a refractive index difference between the core part and the cladding part of 14,
The image produced by transmitted illumination light (') takes advantage of the fact that differences in the brightness and darkness of the boundary parts appear, and this state can be observed on the monitor television 27 provided in this embodiment. Specifically, all vertical sampling lines are set on a television receiver (not shown), the entire brightness distribution of the scanning line is measured along these sampling lines, the boundary between the core part and the cladding part is detected, and the center of this boundary is detected. The sampling line is located at the center of the core part.The sampling line is the optical fiber 13.
．． 14 are set at positions of 100 to 300 micrometers from the abutting end faces of each. A control device 28 that controls the operation of the drive motors 16 and 17 described above is connected to the image processing device 26, and based on a signal from the image processing device 26, the centers of the core portions of the optical fibers 13 and 14 are aligned coaxially. However, in reality, the image processing device 26
This is a differential circuit that functions so that the detection signal of

Therefore, the two optical fibers 13.1 are
4' on a fixed base 11 and a movable base 12, respectively,
After operating the drive source so that the butt ends of the two units come close to each other, automatic operation is started. One microscope 2
3. From the NFC image observed by the TV camera 24,
Optical fiber 13 in a plane perpendicular to this observation direction
．． 14 is detected by the image processing device 26, and the n1 control device 28 operates one of the drive motors 16 so that this value becomes zero. Similarly, the other microscope 22
From the image observed by the television camera 24 through the optical fiber 13°1 in a plane perpendicular to this observation direction,
4 is detected by the image processing device 26, and the control device 28 operates the other drive motor 17vi so that this value becomes zero.

According to experiments, when image processing was performed using a microscope 22° 23 with a magnification of 200 times and a television camera 24 with approximately 1,000 scanning lines, the center of the core could be detected with an accuracy of less than 1 micrometer. It has been found that positioning can be kept to an average of 0.5 micrometers or less. From this state, the presser metal fitting 15 of the movable base 12 is moved a certain amount toward the fixed base 11, and the discharge electrode 18 is energized, and the butt ends of the optical fibers 13 and 14 are fused and spliced by discharge heating. The connection loss can be reduced to a low value of approximately Q, 1 dB. When working on a ship, it is preferable to install the entire apparatus on a vibration-proof table and to set the dimensions and shapes of each part so that resonance does not occur.

As described above, according to the optical fiber automatic connection device of the present invention,
The butted ends of the optical fibers are observed from two directions using transmitted illumination, and image processing is performed based on the contours of the core parts to automatically move the two optical fibers relative to each other so that the centers of the core parts coincide. This makes it possible to perform axis alignment with extremely high precision even for single-mode fibers with small core diameters, which, together with shortening work time and automation, makes it easier to use optical cables on ships. It is possible to make the connection highly reliable.

[Brief explanation of drawings]

FIG. 1 is a working conceptual diagram showing a schematic structure of an embodiment of an automatic optical fiber connection device according to the present invention, FIG. 2 is a block diagram showing its control principle, and FIG. This is a layout diagram showing a part of the structure, and the symbols in the figure are: 11 is a fixed base, 12 is a movable base, 13.14 is an optical fiber, 15 is a presser metal fitting, 16.17F:l: drive motor, 18 is a discharge electrode, 19 is a light source, 20.21 is a light guide, 22.23 is a microscope, 24 is a television camera, 25 is a reflector, 26 is an image processing device, and 28 is a control device. Patent applicant Nippon Telegraph and Telephone Public Corporation representative Patent attorney Shibu Mitsuishi (and 1 other person) Figure 1 4 Figure 2 Figure 3

Claims (1)

[Claims] a positioning drive device capable of relatively moving the abutted ends of two optical fibers to be permanently connected in two directions, one in an opposing direction and one perpendicular to the opposing direction; a fusion device that heats and fuses the butt ends of the two optical fibers; an illumination device that completely illuminates the butt ends of the two optical fibers; a microscope for observing from the two directions; an image processing device for detecting all positional deviations of the core portions of the two optical fibers along the two directions based on images observed by the microscope; and from the image processing device. an optical fiber automatic connecting device comprising: a control device that completely controls the operation of the positioning drive device so that the core portions of the two optical fibers are coaxial based on the detection signal of the optical fiber.