JPS6095506A - Aligning device for optical fiber axis - Google Patents

Abstract

PURPOSE:To align the axes of cores to each other accurately by making a position adjustment by jogging a microscope and a light source so that the microscope and light source has invariably the same position relation. CONSTITUTION:The light source 11 and microscope 14 are jogged and positioned in an (y) direction for vertical observation so that the light source 11, optical fiber 11, and microscope 14 are arranged vertically in a line. Then, the microscope is jogged in an (x) direction and positioned so that the distance between fiber center points is f0 determined by the focal length. There are two optical fibers 1 and 2 to be connected and their relative axis shift is normally several microns, so only one optical fiber is adjusted. In this state, the core positions of the two fibers are observed to detect the axis shift extent of the cores, and an optical fiber support base 4 is moved so that the axis shift is eliminated, attaining the alignment.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fiber optic axis alignment system for highly accurate nuclear detection.

For example, an optical fiber with a small core diameter! In order to reduce the loss in connecting 18 1-T-doped optical fibers, it is necessary to connect 2 optical fibers. There is a center distance that minimizes the deviation between the centers of the two horns (axis misalignment...), and this is aligned.

A conventional method for aligning the core axis of an optical fiber is shown in FIG. One side 1 of the optical fibers to be connected is fixed to a support stand 3, and the other optical fiber is connected to a support box 41 that can be moved slightly in each of the x, y, and z directions as shown in the figure. fixed,
The light 'tA6 enters the optical fiber 1 with 0=I, and the support base 4 is moved by the moving device 5 so that the power of the light that passes through the optical fibers 1 and 2 and reaches the light receiver 7 becomes maximum. Move and align the axis of A. However, with this method,
In general, the location where the light enters, the location where the light is connected, and the location where the optical power is monitored are different, so devices that communicate with each other are required, and workers need to be stationed at each location.
This is particularly inconvenient when the light source location, 72-day location, and connection location are remote.

On the other hand, it has been considered that a method of easily aligning the axis only at the connection location involves visually observing the core in the fiber and aligning the fiber to be connected so that there is no axis deviation. FIG. 2 shows an example of such a method. optical fiber 1
, × perpendicular to the axis of 2.

The light sources 11 and 12 are placed on the extension line of the y-axis, and the light source 11 and 12 are placed on the extension line of the y-axis.
1 za 1! , in the X-axis direction'') through the optical fiber i
I! llR1 - 6 W each, horn and iba image under microscope 14
When the image is enlarged, an image shown in FIG. ζ1 is obtained, and an image 20 is observed near the center of the optical fiber. l, /, :ga-)(, Detects the deviation of the core images of both connected core images, and manually moves the optical fiber support base 4 to the moving device α!'i lL: , 1, moves the
Or, take the first image into the microscope 14.
'l'I! ]τ゛The obtained image signal is sent to the TV 16 'C.
'Enita J-rudotomo 1. 2. From this signal, the image processing device 17 detects the 1, Li-1 horn order] d, and drives the moving device 5 so as to eliminate the axis deviation determined as a result (J. 1. (The axes of opposing optical fibers can be aligned.

When observing 21A in this J, method, light]
7/ Since the rivet is cylindrical, its lens effect generally makes the core's diameter larger than its actual size.
Observed position 1) Will differ from the actual position. Fourth
As shown in the figure, in a plane perpendicular to the observation direction,]
If the axis of 77 is separated by d from the center of the fiber, the center of the core will be at the center of the fiber when the core is focused exactly l on the imaging plane (Fig. 4(a)). On the other hand, it will be observed at a position separated by the refractive index xd=D o of the fiber.

However, when the focus of the microscope is placed elsewhere (
FIG. 4(b)) shows the eccentric ID beam of the observed core.

It will be different. Figure 5 shows D when the focal position is moved.
shows the change in Due to the change in the focal position of number +71 III, there is a large change in the observation position of the core all at once.

Furthermore, a similar phenomenon occurs at the microscope 14 as shown in FIG.
This also occurs when the light source 11 is shifted from the line connecting the optical fibers 1. FIG. 7 shows the relationship between the optical axis shift in FIG. 6 and the observed core position. As expected, the optical axis shift of f1m causes a large change in the observed position.

In this case, when the focal position of the microscope or the optical axis of the light source shifts, the observed core position is greatly affected, and it is extremely difficult to estimate the true core position. It can be seen that the error in alignment is 5-.

-1), in the normal optical fiber axis alignment Ut, as shown in Figure 8(a), at the optical fiber cellars 1 to 4:l Fj 1", it should be at 21. If the optical fiber is connected to the shaded area of 22 at 1N or
) When observing an image through the lr l mirror 13 as shown in 1-1-, if an 80 degree deviation occurs in the superelectricity of the mirror, the virtual image position due to the optical fiber or the mirror of the light lIg+ will be at the original position 23, The focus changes from 24 to 2, and then to 26, and in either case, the focus is 1) 7" and the optical axis shift cannot be avoided.

Also, as shown in Fig. 33 (()), when observing a direct fiber image (!li-direction 1) and a fiber image via a mirror (horizontal direction) at the same time, both images can be viewed simultaneously. J.
61, it is impossible to focus the two at different distances r + r. As mentioned above, the core of the optical fiber to be connected can be directly observed. - When performing 7-axis alignment l, child no j! There was a drawback that accurate core axis alignment was not possible due to error fluctuations in the positional relationship between the fiber, the microscope, and the light source.

The present invention was made in view of the above circumstances, and aims to provide an optical fiber axis alignment device that can accurately align the core axis. It is characterized by the provision of position adjustment for slightly moving the microscope and light source so that the positional relationship is achieved.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 9 is a diagram showing an embodiment of the present invention, and in this figure, the same components as in FIGS. 1 and 2 are given the same reference numerals. The apparatus shown in this figure allows the microscope 1.4 to be moved slightly in the X-axis and V-axis directions perpendicular to the fiber axis. The position adjustment device 31, etc., moves the light sources 11 and 12 in the y-axis and x-axis directions, respectively.
It is configured to include position adjustment devices 32 and 33 for fine movement.

FIG. 9 is a view of the apparatus viewed from the axial direction of the optical fibers 1 and 2, and the structure of the supporting portion of the optical fiber 1.2 is omitted. In this device as well, the optical fiber 1.2 is
Support stand 3 and x, y as shown.

They are each held on a support stand 4 that can be moved slightly in the l-axis direction.

To align the optical fiber axis using the above device, first, the light source 11, the optical fiber 1
The light source 11 and the microscope 14 are slightly moved in the VTj direction so that the light source 11 and the microscope 14 are aligned vertically in a straight line. Mo, microscope and Noah! The distance between the center points of the fibers can be determined by the focal length [. Move the microscope slightly in the X direction to align the position. Connected light) 1 fiber is 1, 2 and 2
Although there are many optical fibers, the relative axis deviation between them is usually on the order of several microns, so the above adjustment only needs to be performed for one of the optical fibers. In this state, observe the core position of each of the two fibers, detect the misalignment of the two fibers, and align the fibers by moving the optical fiber support 4 to eliminate the misalignment of the other axes. .

Next, when the light passing horizontally through the optical fiber from the light source 12 is observed in the perpendicular direction with the mirror 13, the virtual image 34 of the optical fiber and the virtual image 35 of the light source on the mirror are arranged vertically in a straight line. Adjust the position of the light source 12 in the X direction and the microscope 14 in the X direction, and move the microscope in the X direction so that the distance between the microscope and the virtual image 34 of the optical fiber is
The position is adjusted in the direction, the core positions of the two optical fibers are observed, and the amount of axis deviation is detected and the alignment is performed in the same way as in the case of the vertical direction.

By aligning the focal position and optical axis in the vertical and horizontal directions using these steps, it becomes possible to accurately detect the core position and axis deviation without errors due to focal deviation or optical axis deviation. Axis alignment is possible.

FIG. 10 shows an embodiment for accurately adjusting the position as described in the explanation of FIG.
An image processing device 41 extracts focal state information and optical axis deviation information from an image signal obtained by an imaging device 15 attached to the camera, and a control device 42 drives position adjustment devices 31 to 33 according to the requested data. light source 11.12 and microscope 1
4 to 9- The command is J, and the sea urchin is composed of τ.

A typical example of the signal when the optical fiber image is scanned in the direction of the axis and bending angle li is shown in Fig. 11. There are 1B level bands 51 and 52 near the upper and lower edges of the fiber, and there are 1B level bands 51 and 52 in the core part. There is a slight drop in level at the corresponding position.

If there is a misalignment in the optical axis between the optical fiber and the light source, the widths of the dark 1 novel bands 51 and 52 will differ between the upper and lower sides. Furthermore, if there is an optical axis misalignment between the microscope and the optical fiber, the fiber image will not be centered on the entire screen. Roughly speaking, regarding the focal position,
The slope of the fall from the bright level to the dark level on both sides of the dark 1 novel differs depending on the shape of the image, so by monitoring this slope 53.54, you can know the focal point. Gulp.

Figure 12 shows the optical axis deviation Δy in Figure 4111 and the Showa level band! li 1 , 52 width W1. The transformation of W2 into W1
/W2 shows the relationship with I, :4), so when Δy is O, it has a value of 1, and if it goes beyond that, the value of Wl/W2 will be 31 in that direction, becoming more popular than S1 or smaller than 1. (\becomes.

-10- Therefore, the width of the bright level band is detected by the image processing device 41 that inputs the image signal and performs the calculation.
The control device 42 may control the position adjustment devices of the light source and the microscope so that the ratio is 1 and the center of the fiber is located at the center of the screen. Wl/W2 is 1±0.
05, the optical axis deviation can be suppressed to within ±50 μm.

FIG. 13 shows the relationship between the defocus Δf and the slope (differential coefficient) from the bright level to the dark level. When the fiber is focused at the center, it is 8 f.

−〇, the focus shifts to the front side of the fiber (Δf
o〉0) If the slope becomes steeper and the differential coefficient increases, and the focus shifts to the east side of the fiber (Δ10<0> the slope becomes gentler and the differential coefficient decreases. Therefore, the differential coefficient is set to 0.06, for example.
When set to approximately 5±o, oi, at least the focal position shift can be suppressed to within ±15 μm. If the position adjustment device of the microscope is controlled by the control device so that the differential coefficient becomes a constant value in this way, the focal position will always be kept constant.

In addition, the setting value of the differential coefficient is particularly the necessary number of 0.065, 1, which makes it easy to detect the core from the image signal, and the differential coefficient corresponding to the focal state. If you say J:
stomach. Since it is lJ, in this case it is not necessarily as mentioned above. 1: Observation of sea urchins, eccentricity () and actual eccentricity (id) are shown in Figure 5.
=Magnification M(1)・M according to the focal state of Me, Zono 111
ll) to. 1, -)] It is necessary to estimate the true position of A.

By changing the width of the dark-dark level pan and adding a diagonal from the bright level to the dark level on the edge of the optical fiber of the image signal V, it is easy to obtain the optimum light. The movement of the light source is such that the axes O, J, and the focal state are given λ, and the movement of the light source is i'iT fil≦. , control unit b
By using NI III W in 'f42, it is possible to easily automate the process.

In addition, the image embedding fR41 can also have the function of the image processing device 17 for detecting the position described in FIG. A highly accurate axis alignment device can be realized by controlling the moving device 5 that moves the optical fiber support base 4 so as to eliminate the misalignment between the optical fibers to be connected.

As explained above, according to the present invention, the focal position applied to the system for observing the core in the optical fiber is made constant, and the microscope and the light source are adjusted so that the optical axis connecting the light source, the optical fiber, and the microscope is aligned. By providing a position adjustment position for fine movement, the core observation conditions can be kept constant, the correct core position can be detected, and the axis misalignment between the optical fibers to be connected can be accurately determined. By moving the optical fiber fixing stand to eliminate this, extremely accurate core alignment can be achieved.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an optical fiber axis alignment device using the conventional optical power monitoring method, Fig. 2 is an explanatory diagram of an optical fiber axis alignment device with a core direct observation system, and Fig. 3 is an explanatory diagram of an optical fiber axis alignment device using a conventional optical power monitoring method. Figure 4 (a) and (b) are diagrams showing changes in the core observation position due to focal position shift; The figure is an explanatory diagram of the optical axis deviation at tJ when the axis is aligned, and Figure 7 is a demonstration diagram of the change in the observation position.
The figure is an explanatory diagram of the case where axis shift and focus shift occur in ), No. 9
Figures 110 and 1 are all examples of the present invention. Fig. 11 shows an example of the observed optical fiber image signal. One waveform diagram,
Both FIGS. 12 and 13 are six-dimensional diagrams showing the effects of the present invention. 1.2...Hikari-Nono Iba, 3,4...
・Optical fiber support stand, 5...Move! 'JJ outfit,
11.12...Light source, 13...Mirror, 14...Microscope, 15...Imaging device? ! ? , if'i...-1\1117...
...Image processing device, 20...1 part 1, 31.
32.33...Position adjustment device &ll'
1... Image processing device, 42... Control device. Applicant Nippon Telegraph and Telephone Corporation

Claims (2)

[Claims] (1) A microscope placed at a position perpendicular to the optical fiber axis near the butt part of two optical fibers to be connected in a straight line. A light source and a mirror placed on the opposite side of the optical fiber are interposed. The core position of the optical fiber is detected by observing the optical fiber using one or both of the light sources placed in the other orthogonal direction of the optical fiber axis, and the optical fiber fixing table that holds the optical fiber to be connected is installed. In a device that aligns the core axis of an optical fiber by moving, the light source, the optical fiber, and the microscope or the light source, the optical fiber, the mirror, and the microscope are arranged in a straight line or in a straight line taking into account the reflection angle of the mirror, and An optical fiber axis alignment device, characterized in that a position adjustment device is installed to adjust the light source and the microscope slightly so that the focal point of the microscope matches a predetermined position of the fiber. (2) An imaging device that transports the horn/horn image obtained by J: onto a microscope, and this transport image)! The brightness of the image signal scanned in the direction perpendicular to the axis of the image at the i position is 1!11. an image processing device that detects the ratio of the pan F width; The optical fiber shaft alignment device according to claim 1, further comprising a control device for controlling the adjustment device.