JPH09210844A - Optical fiber core position detection method - Google Patents

Abstract

(57) Abstract: It is possible to easily and inexpensively detect the core position of an optical fiber by processing a binary signal representing the brightness of an image. SOLUTION: A pattern plate 4 having a diagonal pattern 5 printed thereon is arranged on one side of optical fibers 1A and 1B, and an image pickup device 7 for photographing the diagonal pattern 5 through the optical fibers 1A and 1B is arranged on the opposite side. The distortion portion P of the image corresponding to the boundary between the core 2 and the cladding 3 of the optical fiber is detected from the image obtained by the device 7, and the position of the core is detected from the position of the distortion portion P.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a core position of an optical fiber, which is used for centering when the optical fibers are fusion-spliced.

[0002]

2. Description of the Related Art When two optical fibers are spliced by abutting the end faces, it is necessary to detect the positions of the cores of both optical fibers and align the positions of the cores before performing the fusion splicing. is there. Conventionally, as a method for detecting the core position of an optical fiber used for such a purpose, light is applied from the side to the optical fiber, and the light transmitted through the optical fiber is generated from a light-dark image produced by the difference in refractive index between the core and the clad. A method for detecting the core position is known (Japanese Patent Laid-Open No. 59-95506).

[0003]

However, the conventional method has a problem that an optical system for detecting a bright and dark image is complicated and expensive because the difference in refractive index between the core and the clad is very small. In addition, the conventional method has a problem that the core is detected from the brightness difference of the obtained bright and dark images, so that the brightness balance needs to be adjusted and the measurement result becomes unstable under the influence of disturbance. Further, since the brightness of the core part is an intermediate brightness, in order to obtain the brightness depth, it is necessary to sample the bright and dark image with, for example, 8 bits, which complicates the hardware and the algorithm for extracting the core. Become.

In view of the above problems, the object of the present invention is simpler, cheaper than conventional ones, and less susceptible to the influence of disturbance.
An object is to provide a method for detecting the core position of an optical fiber.

[0005]

[Means for Solving the Problem] On the other side of the optical fiber,
When an optical image obtained through an optical fiber is observed by arranging a pattern that has diagonal direction to the axis of the optical fiber, distortion due to the difference in refractive index occurs at the position corresponding to the boundary between the core and the clad of the optical fiber. To do. The position of the core can be detected by detecting the position of the warped portion. The present invention applies such a principle.

That is, the present invention provides an image pickup apparatus in which a pattern having an oblique directivity with respect to the axis of the optical fiber is arranged on one side of the optical fiber, and the pattern is imaged on the opposite side of the optical fiber through the optical fiber. Place and
It is characterized in that a distortion portion of an image corresponding to a boundary between a core and a clad of an optical fiber is detected from an image obtained by this image pickup device, and a position of the core is detected from a position of the distortion portion.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. 1A to 1C show an embodiment of the present invention. 1A, 1A and 1B
Is an optical fiber whose core position is to be detected, and is composed of a core 2 and a clad 3. Optical fiber 1A, 1B
After the core position is detected, the cores are arranged with their end faces facing each other in order to align the axes of the cores and perform fusion splicing.

A pattern plate 4 is arranged on one side of each of the optical fibers 1A and 1B. On the surface of the pattern plate 4 on the optical fiber 1A, 1B side, a diagonal pattern 5 as shown in FIG. Light is applied to the diagonal pattern 5 of the pattern plate 4 by the light source 6. Further, an image pickup device 7 for picking up an image of the inclined pattern 5 through the optical fibers 1A and 1B is arranged on the opposite side of the optical fibers 1A and 1B from the pattern plate 4. The imaging device 7 is the optical fiber 1
It converts an optical image obtained through A and 1B into an electric signal, and specifically, a television camera or the like is used.

The image picked up by the image pickup device 7 in the above arrangement is, for example, as shown in FIG. That is, when the oblique line pattern 5 is imaged through the optical fibers 1A and 1B, the oblique line is largely bent by the optical fibers 1A and 1B, and the difference in refractive index between the core 2 and the clad 3 corresponds to the boundary between the core 2 and the clad 3. A distorted portion P of the image occurs at the position.

The image signal obtained by the image pickup device 7 is input to the image processing device 8 where the position of the warped portion P is detected. In the distorted portion P, for example, a black line is displaced in the axial direction of the optical fibers 1A and 1B and becomes discontinuous. Therefore, if the discontinuous portion is detected, the position of the distorted portion P (that is, the position of the core 2) can be detected. become. Since this processing is processing of binary data of white and black (maximum brightness and minimum brightness) (that is, processing can be performed with a brightness depth of 1 bit), it is possible to use a brightness depth of 8 bits as in the past. Compared to processing, memory and other hardware, and core extraction algorithms can be greatly simplified.

As described above, both optical fibers 1A, 1B
If the position of the core 2 is known, align the cores and
Fusing connections can be made. Further, if the core position at the connection portion is detected after the fusion splicing, the connection loss at the connection portion can be estimated.

The shaded pattern 5 of the pattern plate 4 may be a striped pattern as shown in FIG. 2 (in this case, the boundary between white and black will be detected), and the pattern will move to the right and left as shown in FIG. A mesh pattern in which downward diagonal lines intersect may be used, or a curved pattern having diagonal directionality as a whole as shown in FIG.

5 (a) and 5 (b) show another embodiment of the present invention. According to this method, a slit plate 10 having a large number of slits 9 is arranged on one side of the optical fibers 1A and 1B in an oblique direction with respect to the axis of the optical fibers 1A and 1B, and a light source 6 is arranged on the back side of the slit plate 10. And then optical fiber 1
The image pickup device 7 arranged on the opposite side of A and 1B picks up an optical image of the slit pattern obtained through the optical fibers 1A and 1B. The other parts are the same as those of the embodiment of FIG. 1, and therefore, the same parts are denoted by the same reference numerals. With such a configuration, the core position of the optical fiber can be set similarly to the embodiment of FIG.

When the slit plate 10 is used, the gap between the slits 9 may be close to the wavelength of the light from the light source 6 to form a diffraction grating. In order to prevent the slit 9 from being clogged with dust or the like, as shown in FIG.
It is preferable that 0 is embedded in a transparent resin plate or glass plate 11.

FIGS. 7A and 7B show still another embodiment of the present invention. According to this method, a concavo-convex reflection plate 13 having a large number of triangular projections 12 formed obliquely to the axis of the optical fibers 1A and 1B is arranged on one side of the optical fibers 1A and 1B. Brightness obtained through the optical fibers 1A and 1B by the image pickup device 7 arranged on the opposite side of the optical fibers 1A and 1B by applying light from the light source 6 so that the slope on one side of the strip 12 is bright and the slope on the opposite side is dark. The optical image of the pattern is captured. Figure 1
Since it is the same as that of the above embodiment, the same reference numerals are given to the same portions. With such a configuration, the core position of the optical fiber can be set similarly to the embodiment of FIG. When the uneven reflection plate 13 is used, the distance between the triangular protrusions 12 may be set close to the wavelength of the light from the light source 6 to form a diffraction grating.

[0016]

As described above, according to the present invention, when a pattern having an oblique directionality is imaged through an optical fiber, the optical fiber is distorted due to image distortion occurring at the boundary between the core and the clad of the optical fiber. Since the position is detected, it is possible to detect the boundary between the core and the clad of the optical fiber by processing the binary signal that represents the brightness of the image, greatly simplifying the hardware and the algorithm for extracting the core. can do. Therefore, the cost of the detection device can be reduced. Further, since it is sufficient to make the light and dark of the image clear at the time of detection, there is an advantage that it is unlikely to be affected by disturbance.

[Brief description of drawings]

FIG. 1A is a plan view showing an embodiment of the present invention,
(B) is a bb line arrow view of (a), (c) is explanatory drawing which shows the image captured with the imaging device.

FIG. 2 is a front view showing another example of the pattern plate used in the present invention.

FIG. 3 is a front view showing still another example of the pattern plate used in the present invention.

FIG. 4 is a front view showing still another example of the pattern plate used in the present invention.

5A is a plan view showing another embodiment of the present invention, and FIG. 5B is a view taken along the line bb of FIG.

FIG. 6 is a cross-sectional view showing another example of the slit plate used in the present invention.

FIG. 7A is a plan view showing still another embodiment of the present invention, and FIG. 7B is a view taken along the line bb of FIG.

[Explanation of symbols]

 1A, 1B: optical fiber 2: core 3: clad 4: pattern plate 5: diagonal pattern 6: light source 7: imaging device 8: image processing device 9: slit 10: slit plate 11: transparent glass plate 12: triangular ridge 13: Concavo-convex reflector P: Distorted part of image

Claims (1)

[Claims] 1. A pattern having oblique directionality with respect to the axis of the optical fiber is arranged on one side of the optical fiber, and an image pickup device for picking up the pattern through the optical fiber is arranged on the side opposite to the pattern of the optical fiber. Optical fiber core position detection characterized by detecting the distortion portion of the image corresponding to the boundary between the core and the clad of the optical fiber from the image obtained by this imaging device and detecting the core position from the position of the distortion portion Method.