JPS6256483B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for aligning optical fibers to abut each other with their axes aligned when connecting optical fibers of the same diameter. It is something.

In order to reduce optical loss at the joint between optical fibers, that is, connection loss, as much as possible, it is necessary to connect the end faces of the optical fibers with their axes aligned. Conventionally, the following methods are known. That is, a method of preparing a plate having a precisely finished V-groove, fitting the ends of both optical fibers to be connected into the V-groove of this plate, and abutting both end surfaces within the V-groove, or a method of connection. This is a so-called two-field microscope in which the ends of both optical fibers to be used are set in a holder that can be moved and adjusted in three-dimensional directions relative to each other, so that images from two mutually orthogonal directions can be captured within the same field of view. While operating both holders to position the edges of the ends of both optical fibers, that is, the images of both edges in the diametrical direction perpendicular to the observation direction, on the same straight line, the end face of the optical fiber is This is a way to make them collide with each other.

In the case of the above two methods, the position of the optical fiber in two directions perpendicular to the axis is mechanically regulated in the former case by the alignment function of the V-groove itself, and in the latter case This is done by direct manual operation based on observation from two directions using a two-field microscope.
It is necessary to prepare a plate with grooves, but V
Since the groove machining itself requires extremely advanced technology, the plate price is extremely high.
In the latter case, a two-field microscope should be prepared, or if a regular microscope is used, two should be prepared for observation from two directions, or a movable structure should be provided to enable observation from two directions. A microscope has to be prepared, and the equipment itself is expensive and equipment costs are high, and the alignment work itself is troublesome.

For this reason, especially when using the latter method, a normal microscope using an optical system with a shallow depth of focus is used instead of a two-field microscope to first measure the positional deviation of both optical fibers in a direction perpendicular to the observation direction. Rough alignment is performed by locating the edge lines of the strands on the same straight line, and then the positional deviation of both strands of optical fiber in the observation direction is corrected by, for example, adjusting the outer peripheral surface of one of the strands of optical fiber. Attempts have also been made to align the outer peripheral surfaces of other optical fibers by moving them up and down so that when focusing, the outer peripheral surfaces of the other optical fibers can be captured with the same sharpness. This method requires skill and is often insufficient in accuracy. Furthermore, it has the disadvantage that the alignment process itself is hardly alleviated.

The present invention has been made in view of the above circumstances, and its purpose is to utilize bright lines appearing on the outer peripheral surfaces of both optical fibers to be connected when the outer peripheral surfaces of the two optical fibers are irradiated with light. Accordingly, it is an object of the present invention to provide a method for aligning optical fibers that allows alignment of both optical fiber strands to be easily, quickly, and accurately performed only by observation from one direction. The method for aligning optical fibers according to the present invention involves irradiating the outer peripheral surfaces of the respective ends of optical fibers having the same diameter with light, and aligning the corresponding bright lines of the outer peripheral surfaces of the respective ends that appear due to the light irradiation. It is characterized by being located on a straight line.

The present invention will be specifically explained below based on drawings showing its implementation state. FIG. 1 is a perspective view showing the implementation state of the method for aligning optical fibers according to the present invention (hereinafter referred to as the method of the present invention), and in the figure, 1 and 1' are optical fiber strands of the same diameter to be connected to each other. And,
It is set in the optical fiber connection device 2. The optical fiber connecting device 2 includes a pair of holders 21, 21' that move relatively in three dimensions while positioning and holding both optical fiber wires 1, 1' to be connected, and a light beam set in both holders 21, 21'. Fiber wire 1,
It is equipped with a microscope 22 for magnifying observation of both ends of the optical fibers 1', a light source 23 for light irradiation, and a microtorch 24 for melting and bonding the mutually connected end surfaces of the optical fibers 1 and 1'. Optical fiber wire 1,
Each end of 1' is connected to the V-shaped groove 21 of each holder 21, 21'.
a, 21a', and presser rods 21b, 21
b' is positioned and held within the V-shaped grooves 21a, 21a'. Then, by operating each holder 21, 21', both optical fiber strands 1,
The axes of the optical fibers 1 and 1' are made to substantially coincide with each other, with the end faces of the optical fibers 1' being brought close to each other. Next, under illumination by the light source 23, the ends of the optical fibers 1 and 1' are observed under magnification through the microscope 22, and fine adjustment of the alignment is performed.
Both optical fibers 1, which can be seen within the field of view of 2,
The bright line appearing on the outer peripheral surface of 1' is used.

FIG. 2 is a schematic enlarged plan view showing the optical fibers 1, 1' and the light source 23 to be connected;
The figure is a schematic diagram viewed from the - line direction in Figure 2, in which S ₁ , S ₂ , S ₁ ', and S ₂ ' are edge lines, and B ₁ and B ₁ ' are bright lines. The edge lines S ₁ , S ₂ , S ₁ ′, and S ₂ ′ are on both sides of the optical fiber strands 1 and 1′ in the diametrical direction perpendicular to the observation direction by the microscope 22, for example, on both sides of the optical fiber strands 1 and 1′.
is located on the optical axis (white arrow mark) of the objective mirror 22a of the microscope 22, the optical fiber strands appear along both sides of the optical fiber strands 1, 1' in the diametrical direction perpendicular to the optical axis. 1,1' is the incarnation line,
In addition, the bright lines B ₁ and B ₁ ' are the lines of the optical fibers when the irradiated light from the light source 23 is reflected at points O and O' on the outer peripheral surface of the optical fibers 1 and 1' and captured by the microscope 22. This is a straight line that appears on the outer circumferential surface of optical fibers 1 and 1', passing through O and O' and parallel to the axis of the optical fiber strands 1 and 1'. The edge lines S ₁ , S ₂ , S ₁ ′, and S ₂ ′ indicate the optical fiber strands 1 and 1′ in the observation direction of the microscope 22.
, that is, the direction perpendicular to the observation direction (hereinafter referred to as the front-back direction), or the position of the light source 23, on both sides in the diametrical direction of the optical fibers 1 and 1'. In contrast, emission lines have the property of appearing.
When the positions of the optical fibers 1 _{and 1} ' change in the vertical and front-back directions, the microscope 22 receives light with different reflection angles on the outer peripheral surfaces of the optical fibers 1 and 1' _, respectively. As a result, the positions of the bright lines B 1 _and B 1 ' on the outer peripheral surface of the optical fibers 1 and ₁ ' will inevitably change, and the width dimensions of the bright lines B ₁ and B ₁ ' will also change accordingly. The positions and width dimensions of the bright lines B ₁ and B ₁ ' on the outer peripheral surface of the optical fibers 1 and 1' are based on the axis of the optical fibers 1 and 1' with respect to the objective mirror 22a of the microscope 22 and the light source 23. This can only be specified by setting the core wire position to a predetermined position. When the two bright lines B ₁ and B 1 ' appearing on the outer peripheral surfaces of the optical fibers 1 and ₁ ' are captured within the field of view of the microscope 22, each of the bright lines on the outer peripheral surfaces of the optical fibers 1 and 1' By aligning the positions of the bright lines B ₁ and B ₁ ′ on a straight line with the widths of both the bright lines B ₁ and B ₁ ′ combined, both optical fiber strands 1,
It is possible to determine the position of the axial center line of optical fiber 1', in other words, to position both axial center lines on the same straight line, and it is possible to align both optical fiber strands 1, 1'.
At this time, the alignment of the optical fibers 1 and 1' in the front-back direction is performed by positioning the edge lines S _{1 ,} S ₂ , S ₁ ', and S 2 ', which appear thinner than the bright lines B ₁ and B ₁ ', on the same straight line. By moving the optical fiber strands 1 and 1' in the front-rear direction, the optical fiber strands 1 and 1' are aligned in the vertical direction so that the bright lines B ₁ and B ₁ ' are aligned on the same straight line with their widths aligned. By moving the lines 1 and 1' in the vertical direction, alignment can be performed more accurately and quickly than when using only the bright lines B ₁ and B ₁ '. That is, for example, optical fiber 1,
1' is captured within the field of view of the microscope 22 as shown by the solid line in FIG.
Since S ₁ and S ₁ ′ and S ₂ and S ₂ ′ are shifted in the front-back direction by the width l, operate the holder 21 (or 21 ′) to align the optical fiber 1 (or 1 ′) with the arrow mark. As shown in the figure, the edge lines S _{1 and S 1 ', and S 2 and S 2 ' are made to coincide with each other on the same straight line by moving the front side by l to make the state shown by the two-dot chain line, that is, the edge lines S 1} and S ₁ ', and S ₂ and S ₂ ' coincide with each other on the same straight line. In this state, as shown in FIG. 3, the optical fiber strand 1 moves from the position shown by the solid line to the position shown by the two-dot chain line, and as a result, the optical fiber strands 1, 1'
The axes X and X' are no longer misaligned in the front-rear direction with respect to the direction of the white arrow, which is the direction of observation by the microscope 22, and only the misalignment in the vertical direction remains. In other words, as shown in the explanatory diagrams of Figs. 4 and 5, the corresponding edge lines S ₁ and S ₁ ', and S ₂ and S ₂ ' coincide on the same straight line (However, strictly speaking, the edge lines of the optical fiber 1 and 1'), but the bright lines B ₁ and B ₁ ' are not on the same straight line.

Then, by moving the holder 21 (or 21') vertically and moving the optical fibers 1 and 1' relative to each other in the vertical direction, the bright lines B ₁ and B ₁ ' are aligned so that their widths match. When they are aligned, the holder 21 (or 21') is moved and the optical fiber 1 (or 1') is moved in the axial direction of the optical fiber 1, 1'. When the end faces are abutted against each other, both end faces are abutted with their axes aligned on the same straight line. In addition to aligning the appearance in this way, for example, the optical fiber 1
A reference light source is attached to the other end, and an optical fiber 1'
A light receiver is coupled to the other end of each of the light sources, and the light from the reference light source is received by the light receiver through the abutting portion of the optical fibers 1 and 1', and the light receiving level is maximized at that time. After correcting the alignment to minimize the loss at the joint, microtorch 2
4 is ignited, and both ends of the optical fiber elements 1 and 1' are fused and bonded.

FIG. 6 is a schematic diagram showing another embodiment of the method of the present invention, and FIG. 7 is a schematic diagram seen from the - line direction of FIG. 6, in which two light sources are arranged at different angles with respect to the optical axis of the objective mirror. The two bright lines B ₁ , B ₁ ′, B ₂ , B ₂ ′ are generated on the outer peripheral surface of each optical fiber strand 1, 1′, and are generated by the same light source 23 or 23′, respectively. By aligning the bright lines _B1 and _B1 ' or _B2 and _B2 ' on the same straight line, the axes of the optical fibers 1 and 1' are aligned in the vertical direction. I do. That is, as described above, first move the optical fibers 1, 1' in the front-back direction under a microscope, position the corresponding edge lines on the same straight line, and then move the optical fibers 1, 1' in the front-back direction. After alignment, the optical fiber elements 1, 1' are moved vertically to align the emission lines from the same light source with each other, and the axes of the optical fibers 1, 1' are aligned. Position the lines on the same straight line. Other operations are the same as in the embodiment described above. By providing a plurality of bright lines on the outer circumferential surfaces of the optical fibers 1 and 1', it is not only easier to align the optical fibers 1 and 1' in the vertical direction, but also the alignment accuracy is improved. do. As described above, in the method of the present invention, when abutting the end faces of optical fibers of the same diameter to be connected with their axes aligned, the bright line appearing on the outer peripheral surface of the optical fiber is used. By observing the ends of both optical fibers to be connected under magnification from one side, the axes can be positioned on the same straight line, and there is no need to prepare a two-field microscope or the like as in the past. This invention not only reduces the weight of the equipment required for alignment and makes it easier to carry the equipment during field work, but also allows alignment work to be performed easily and quickly, and has high alignment accuracy. It has excellent effects.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the implementation state of the method of the present invention;
Fig. 2 is a schematic enlarged plan view showing the optical fiber wire and light source to be connected, Fig. 3 is a schematic diagram as seen in the - line direction of Fig. 2, and Fig. 4 is a state in which the method of the present invention is implemented. Fig. 5 is an explanatory diagram showing - of Fig. 4.
FIG. 6 is a schematic enlarged plan view showing another implementation state of the method of the present invention, and FIG. 7 is a schematic diagram seen in the - line direction of FIG. 6. 1, 1'... Optical fiber wire, 21, 21'...
Holder, 22...Microscope, 23, 23'...Light source, _B1 , _B1 ', _B2 , _B2 '...Emission line, _S1 , _S1 ', _S2 ,
S ₂ ′...edge line.

Claims (1)

[Claims] 1. In an optical fiber alignment method in which the axes of optical fibers of the same diameter to be interconnected are aligned and their ends are abutted, the outer circumferential surfaces of the respective ends of the optical fibers to be abutted are 1. A method for aligning an optical fiber, which comprises irradiating light and positioning corresponding bright lines on the outer circumferential surface of each end that appear due to the irradiation on the same straight line.