JPH0829642A - Method for measuring eccentricity of optical connector and device therefor - Google Patents

Abstract

PURPOSE:To provide a method for measuring eccentricity of an optical connector capable of measuring the eccentricity direction of the optical connector with high accuracy and high reliability without damaging the end face of the optical connector and a device therefor. CONSTITUTION:A ferrule 2 of the optical connector is inserted into a split sleeve 4 and is positioned and held in an arbitrary rotating direction of a circumferential direction. The emitted light from an optical fiber is condensed by an objective lens 10 and is received by a CCD 8. The two-dimensional position of a received light spot image 13 is detected by an image processor 12 and the ferrule 2 is rotated in the circumferential direction. The eccentricity direction of the optical fiber core is decided from the central position 14a of the rotating locus circle 14 of the light spot image 13 and the position of the light spot image 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical connector eccentricity measuring method and apparatus for detecting an eccentricity direction of an optical connector used for optical communication.

[0002]

2. Description of the Related Art An optical connector used in an optical communication system is required to have a low connection loss at an optical connection portion, and therefore, optical connectors of opposite optical connectors are assembled so that eccentric directions of the optical fiber cores coincide with each other. The eccentricity of the optical connector means that the outer diameter of the ferrule is assumed to be a perfect circle, and the center of this perfect circle does not coincide with the center of the actual optical connector core. , To detect the eccentric direction of the optical fiber core with reference to the outer diameter of the ferrule.

FIG. 6 is a front view of the ferrule viewed from the optical axis direction, and FIG. 7 is a side sectional view of the optical connector. The eccentricity of the optical connector will be described with reference to the same figure. In the figure, 31 is a ferrule, 32 is an optical fiber, 32a is an optical fiber core,
33 is a brim portion of the ferrule 31, 34 is a nylon jacket, and 35 is a PVC outer cover.

As a procedure for assembling the optical connector, first, the PVC outer sheath 35 of the optical fiber cord and the nylon jacket 3 are used.
4 and the primary coat adhering to the optical fiber 32 are removed. Next, the optical fiber 32 is inserted into a ferrule 31 filled with an adhesive, that is, a core made of zirconia having good outer diameter accuracy and concentricity, and then bonded and fixed to the ferrule 31 by high temperature treatment. Then, the optical fiber 32
After the adhesive is fixed to the ferrule 31, the end face of the ferrule 31 is polished into a convex spherical surface, and these are assembled in a housing (not shown) of the optical connector, whereby the assembly of the optical connector is completed. The optical connectors are connected by inserting a pair of optical connectors into split sleeves in the adapter and physically contacting the end faces of the optical connectors. As described above, in the optical connector, the optical connection is realized by positioning the optical fiber cores facing each other on the basis of the outer diameter of the ferrule. Therefore, in order to reduce the loss of the optical connector connection, it is necessary that the relative optical axis shift does not occur between the optical fiber cores. One way to achieve this is to use a ferrule with excellent concentricity and outer diameter accuracy and an optical fiber with little core eccentricity, and also select and use the ferrule inner diameter so that the clearance between the optical fiber outer diameter and ferrule inner diameter is small. It can be assembled. However, even if they are strictly selected and used, each selection item has an error of about 0.5 μm. Therefore, when assembling the optical connector, an eccentricity amount of about 2 μm at the maximum exists based on the ferrule outer diameter of the optical connector. This value is the eccentricity of the ferrule on one side. Since the two ferrules face each other when the optical connector is connected, the maximum eccentricity is 4 μm. For example, in the optical connector for single mode optical fiber for optical communication, the connection loss is 2 dB or more. Becomes On the other hand, optical connectors for optical communication are required to have low loss optical connection (for example, connection loss of 1 dB or less). In this way, in the method of selecting and using the parts to reduce the loss, there is a problem that the cost of the optical connector is increased due to the increase of the cost due to the selection of the parts and the reduction of the yield in the assembly. Therefore, in the optical connector for optical communication, a method of detecting the eccentric direction of the fiber core in the ferrule and performing positioning to reduce the relative optical axis shift area between the opposing optical fiber cores and reduce the connection loss is adopted. There is.

8 to 10 show a conventional example for detecting the eccentric direction. 8 is a schematic configuration diagram of a conventional eccentricity measuring device, FIG. 9 is a front view of an eccentricity detection ferrule seen from the optical axis direction, and FIG. 10 is a front view of a test ferrule seen from the optical axis direction. Among them, 41 is a stabilized LD light source, 42 is an eccentricity detection ferrule, 42a is a ferrule collar portion, 42b is an optical fiber core, 43 is an eccentricity measurement optical cord, 44 is an LD light source connection optical connector, 45 is an adapter, and 46 is The ferrule to be inspected, 47 is an optical cord, 48 is a ferrule on the terminating side, 4
Reference numeral 9 is a light receiving element, and 50 is a power meter.

This measuring method is a method called an eccentricity master method, in which a stabilized LD light source 41 is attached to an eccentricity detection ferrule 42.
After connecting the optical cord 43 for eccentricity measurement which has at one end,
The eccentricity detection ferrule 42 and the eccentricity measurement optical cord 43 in which the optical fiber is decentered in a predetermined direction are connected, and the eccentricity detection ferrule 42 and the test ferrule 46 for detecting the eccentricity direction are connected via the adapter 45. And connect the end ferrule 48 of the optical cord 47 to the power meter 50.
Connected to the light receiving element 49. Eccentricity detection ferrule 42
As shown in FIG. 9, the eccentricity detection ferrule 42 is formed so that the direction of eccentricity coincides with one of the four notch grooves provided in the flange portion 42a (groove M1 in FIG. 9), The deviation amount between the center O of the eccentricity detection ferrule 42 and the center of the optical fiber core 42b is 0.5 μ.
m or more is used.

When the eccentricity detection ferrule 42 and the test ferrule 46 are connected via the adapter 45, a connection loss proportional to the amount of relative eccentricity between the optical fiber cores 42b and 46b of both ferrules 42 and 46 occurs. Therefore, in order to detect the eccentric direction of the test ferrule 46, the position where the relative eccentric amount between the optical fiber cores 42b and 46b is the smallest, that is, the connection loss value displayed on the power meter 50 is the smallest. Collar 42a of inspection ferrule 42
The position of the notch groove may be selected from four positions. The eccentric direction of the optical connector can be uniquely fixed by assembling the notch groove indicating the eccentric direction together with the protrusion provided in the optical connector. As a result, the eccentricity master method is characterized in that the relative position error between the opposing optical fiber cores is reduced, that is, the optical connection with low loss can be realized.

[0008]

The above measuring method has an advantage that the eccentric direction can be easily measured without using a special device, but since it is a contact type measuring method, there is a possibility that the end face of the optical fiber is damaged. It was In addition, since the eccentric direction is determined from indirect information only on the connection loss, if there is dust or scratches on the end face, excess connection loss will occur due to these factors, and the eccentric direction will be mistakenly recognized and reduced. There is a problem in that lossy optical connector contact cannot be made.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an eccentricity measuring method for an optical connector and an apparatus therefor which does not damage the end face of the optical connector. . Another object is to provide an eccentricity measuring method for an optical connector and an apparatus therefor capable of measuring the eccentricity direction of the optical connector with high accuracy and high reliability in addition to the above-mentioned object.

[0010]

In order to achieve the above object, the present invention provides, in claim 1, an optical connector eccentricity measuring method for measuring an eccentricity direction of an optical fiber core in an optical connector. Grip the light emitted from the optical connector with the objective lens, receive it with the photoelectric conversion element, and detect the two-dimensional position of the received light spot image by image processing. The eccentric direction of the optical fiber core is determined from the positional relationship of the spot images.

According to a second aspect of the present invention, in an eccentricity measuring method of an optical connector for measuring an eccentricity direction of an optical fiber core in the optical connector, a ferrule of the optical connector is positioned and gripped in an arbitrary rotational direction in a circumferential direction, and the ferrule of the optical connector is removed from the optical connector. The emitted light is collected by the objective lens and received by the photoelectric conversion element, and the two-dimensional position of the received light spot image is detected by image processing, and the ferrule of the optical connector is rotated in the circumferential direction to generate the light spot image. The center position of the circle of rotation locus is obtained, and the eccentric direction of the optical fiber core is determined from the positional relationship between the center position and the light spot image.

Further, in claim 3, a holding means for positioning and holding the ferrule of the optical connector in an arbitrary rotational direction in the circumferential direction, an objective lens for collecting the light emitted from the optical connector, and an objective lens for collecting the light. An eccentricity measuring device for an optical connector is provided with a photoelectric conversion element that receives emitted light and an image processing device that detects a two-dimensional position of a light spot image received by the photoelectric conversion element by image processing.

According to a fourth aspect of the present invention, in the eccentricity measuring device for an optical connector according to the third aspect, a relay lens for converging light emitted from the optical connector and forming an image at a focal position of the objective lens is provided. .

[0014]

According to the eccentricity measuring method of the optical connector of the first aspect, the ferrule of the optical connector is gripped, the light emitted from the optical connector is collected by the objective lens and received by the photoelectric conversion element, and the received light is received. The two-dimensional position of the spot image is detected by image processing, and the eccentric direction of the optical fiber core is determined from the reference point of the eccentric direction and the position of the optical spot image.

According to the eccentricity measuring method of the optical connector of the second aspect, the ferrule of the optical connector is positioned and held in an arbitrary rotational direction in the circumferential direction, and the light emitted from the optical connector is condensed by the objective lens. The light is received by the photoelectric conversion element, the two-dimensional position of the received light spot image is detected by image processing, and the ferrule of the optical connector is rotated in the circumferential direction so that the center position of the rotation locus circle of the light spot image and the light spot image are detected. The eccentric direction of the optical fiber core is determined from the position.

According to the eccentricity measuring device for an optical connector of claim 3, the ferrule of the optical connector is positioned and gripped by the gripping means in an arbitrary rotational direction in the circumferential direction, and the light emitted from the optical connector is collected by the objective lens. Be illuminated. Further, since the outgoing light condensed by the objective lens is received by the photoelectric conversion element, and the two-dimensional position of the light spot image received by the photoelectric conversion element is detected by the image processing device,
The eccentric direction of the optical fiber core is determined based on the reference point of the eccentric direction or the center position of the circle of the rotation locus of the optical spot image and the position of the optical spot image obtained by rotating the ferrule of the optical connector in the circumferential direction. .

According to the eccentricity measuring device for an optical connector of claim 4, in addition to the effect of claim 3, the light emitted from the optical connector is condensed by the relay lens and imaged at the focal position of the objective lens. Therefore, the position of the core image of the optical fiber is apparently moved to the focus position of the objective lens, and the distance from the end face of the optical fiber to the objective lens can be lengthened.

[0018]

1 to 3 show a first embodiment of the present invention. FIG. 1 is a schematic configuration diagram showing an eccentricity measuring device for an optical connector, FIG. 2 is a partially enlarged view thereof, and FIG. It is a front view of the ferrule seen from the axial direction. In the figure, 1 is an optical cord, 2 is a ferrule to be detected for detecting eccentricity direction, 2a is a flange portion of the ferrule 2, M1 to M4 are notched grooves provided in the flange portion 2a, and 3 is the other end side of the optical cord 1. Ferrule, 4 is a split sleeve for holding the ferrule 2, 5 is a white light source, 5a
Is white light, 6 is a hollow split sleeve holder that holds the split sleeve 4, 7 is a measuring device body, and 8 is a photoelectric conversion element C
CD, 9 is a holder, 10 is an objective lens, 11 is an optical fiber, 11a is an optical fiber core, 12 is an image processing device, 1
3 is a light spot image on the CCD 8, 14 is a rotation locus circle obtained from the centers of four light spot images, and 14a is the center position of the rotation locus circle.

An embodiment for detecting the eccentric direction will be described below with reference to FIGS. 1 to 3. Detecting the eccentric direction of the optical connector is performed by the optical fiber 11 in the ferrule 2.
Is to determine the cutout groove (M3 in FIG. 3) of the collar portion 2a having the shortest distance in the eccentric direction of the core 11a.

First, the test ferrule 2 attached to one end of the optical cord 1 with optical connectors at both ends is inserted into the split sleeve 4 attached to the tip of the eccentricity measuring device body 7. At this time, in order to perform the positioning between the eccentric direction of the core 11a of the optical fiber 11 and the cutout grooves M1 to M4, the key 9a provided with the cutout groove M1 of the ferrule 2 under test at the tip of the holder 9a.
Insert according to. This inserted ferrule 2
The core 11a at the tip of is abutted against the tip of the split sleeve holder 6 in the split sleeve 4 or a stopper formed by another component, and is positioned at the focal position f1 of the objective lens 10. As the split sleeve 4, it is desirable to use a zirconia sleeve that is used in optical connector adapters. By using this, it is possible to absorb variations in the ferrule outer diameter, and repeat position repeatability (XY Direction), high-precision eccentricity measurement becomes possible. The split sleeve 4 is inserted and fixed in a hollow split sleeve holder 6 having an outer diameter slightly larger than the inner diameter of the split sleeve 4 (equivalent to the outer diameter of the ferrule 2). Further, since the split sleeve holder 6 and the CCD 8 are fixed to the eccentricity measuring device main body 7, respectively, the split sleeve 4
The distance between the CCD and the CCD 8 is also kept constant.

Next, in order to detect the position of the core 11a in the inspected ferrule 2, the other end ferrule 3 emits white light 5a.
Incident. The incident white light 5a propagates in the optical code 1 and exits from the core 11a in the test ferrule 2, passes through the void 6a in the split sleeve holder 6, and then enters the objective lens 10 to be on the CCD 8. Image on. This CC
Center C of the two-dimensional position of the light spot image 13 formed on D8
1 is obtained using the image processing device 12. Next, the ferrule 2 is rotated in the circumferential direction, that is, about the Z axis by 90 degrees, and the next cutout groove M2 is inserted in alignment with the key 9a, and the center C2 of the light spot image 13 is obtained by the image processing device 12. This operation is performed on all of the four cutout grooves M1 to M4 to obtain the centers C1 to C4 of the four points of the light spot image 13. In this case, for example, the center C1 corresponds to the center of the light spot image 13 when the key 9a is aligned with the cutout groove M1. Therefore, the centers C1 to C4 of the four light spot images 13
The ferrule rotation center, that is, the center position 14a of the ferrule 2 can be obtained from the rotation locus circle 14 of C4.

From the above, the corresponding positional relationship between the center position 14a of the ferrule 2, the respective cutout grooves M1 to M4 of the ferrule 2 and the centers C1 to C4 of the light spot image 13 is found, and therefore the center of the light spot image 13 is obtained. The notch groove closest to the position 14a, that is, the eccentric direction of the optical connector can be detected. For example, in FIG. 1, the cutout groove M1
Center C of the light spot image 13 when the key 9a and
Since the cutout groove closest to 1 is M3, it is determined that the core 11a of the optical fiber 11 is eccentric in the direction of the cutout groove M3.

Thus, the center C1 of the light spot image 13 is
The advantage of this embodiment in which the rotation locus circle 14 is obtained from C4 is that the centers C1 to C4 of four points are on the rotation locus circle 14 when dust or the like is present on the side surface of the ferrule or in the split sleeve 4. Since accurate plotting is no longer possible, it is possible to promptly know a measurement failure due to dust, adhered matter, scratches, etc., and it is possible to reliably prevent erroneous recognition in the eccentric direction. Further, in this embodiment, since the measurement can be performed without contacting the end face of the optical fiber 11, it is possible to reliably prevent the end face of the optical fiber 11 from being damaged.

On the other hand, in the case where dust, deposits, etc. can always be removed by cleaning the inside of the ferrule 2 and the split sleeve 4, the virtual center of the split sleeve 4 on the CCD 8 or the center of the ferrule 2 to be inserted is preliminarily eccentric. The light spot image 1 formed on the CCD 8 is obtained as the reference point of
The notch grooves M1 to M4 indicating the eccentric direction can be determined by measuring the center of No. 3 once, and high-speed eccentricity measurement is possible.

By the way, in order to detect the eccentric direction with higher resolution, it is necessary to use a high-magnification objective lens. However, as shown in the first embodiment,
In the split sleeve holder 6, it is necessary to form a void 6a so as not to block the light emitted from the optical fiber 11. Therefore, the higher the magnification of the objective lens, the NA of the objective lens.
Becomes a large value, and as a result, the gripping margin of the split sleeve holder 6, that is, the portion inserted into the split sleeve 4, becomes shorter, which makes the gripping of the split sleeve 4 unstable and lowers the measurement accuracy. Become. To solve this,
FIGS. 4 and 5 show an embodiment in which a grasping margin having a sufficient length can be ensured even with the use of a high-magnification objective lens, and more accurate measurement is possible.

That is, FIGS. 4 and 5 show a second embodiment of the present invention. FIG. 4 is a schematic configuration diagram of an eccentricity measuring device, FIG. 5 (a) is a side sectional view of a stopper, and FIG. (B) is a front view thereof. In the figure, 21 is a minutely formed relay lens, 22 is a stopper for positioning the end face of the optical fiber in the ferrule at the focal position f3 of the relay lens 21, and 23 is a split sleeve holder incorporating the relay lens 21. . The same components as those in the above-mentioned embodiment are designated by the same reference numerals. Further, in this embodiment, the eccentricity measuring method for detecting the eccentricity direction by using the image processing is the same as that of the first embodiment, and therefore only the optical system part having a different configuration will be described.

The present embodiment is characterized in that the split lens holder 23 is provided with the relay lens 21. The ferrule 2 is inserted into the holder 9 having the split sleeve 4, and the end face of the optical fiber 11 is used as the stopper 22. By abutting, it is positioned at the focal position f3 of the relay lens 21 (Z-axis direction). The stopper 22 may have a simple structure in which a circular void 22a is formed in the center of a disk-shaped member, and the diameter of the void 22a is large enough not to block the light emitted from the optical fiber core 11a. If there is a gap

The relay lens 21 is a split sleeve holder 23.
The split sleeve holder 23 is fixed inside the main body 7. The light emitted from the optical fiber core 11a is condensed by the relay lens 21 and is imaged at the focal position f2 of the objective lens 10. This allows
The position of the image of the core 11a of the optical fiber 11 is set to the objective lens 10
It can be apparently moved to the focal point position f2. As a result, the light emitted from the optical fiber 11 enters the objective lens 10 without being interfered by the split sleeve holder 23, so that the gripping margin of the split sleeve 4 can be lengthened and the ferrule 2 can be stably gripped. can do. Therefore, a high-magnification objective lens 10 can be used without lowering the measurement accuracy, and highly accurate detection of the eccentric direction with good reproducibility can be realized. Further, although the image position converting function is explained with one relay lens 21 in the present embodiment, in actuality, in order to reduce chromaticity, spherical aberration and the like, it is preferable to use a group lens such as an achromatic lens. It is desirable for obtaining image quality. In addition, although the configuration using the existing objective lens is shown in consideration of economy, the same function can be realized by applying an aspherical lens to the relay lens and the imaging lens. The lens diameter configuration is simplified and the device can be downsized.

[0029]

As described above, according to the eccentricity measuring method of the optical connector of the first aspect, the eccentric direction of the optical connector can be detected in a non-contact manner by combining the image forming optical system and the image processing. Therefore, it is possible to reliably prevent damage to the end face of the optical connector, which has been a problem in the conventional contact measurement method.

According to the eccentricity measuring method of the optical connector of the second aspect, in addition to the effect of the first aspect, even when dust or the like adheres to the end face of the optical connector, such a measurement trouble can be promptly known. Therefore, it is possible to reliably prevent erroneous recognition of the eccentric direction, and it is possible to measure the eccentric direction of the optical connector with high accuracy and high reliability.

According to the eccentricity measuring device for an optical connector of claim 3, damage to the end face of the optical connector can be reliably prevented,
Moreover, it is possible to specifically realize an apparatus capable of measuring the eccentric direction of the optical connector with high accuracy and high reliability.

According to the optical connector eccentricity measuring device of the fourth aspect, in addition to the effect of the third aspect, it is possible to sufficiently secure the grip portion of the ferrule between the end face of the optical fiber and the objective lens. Therefore, the ferrule can be stably gripped, and the measurement accuracy can be improved by using the high-magnification objective lens.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an eccentricity measuring device showing a first embodiment of the present invention.

FIG. 2 is a partially enlarged view of the eccentricity measuring device.

FIG. 3 is a front view of the ferrule seen from the optical axis direction.

FIG. 4 is a schematic configuration diagram of an eccentricity measuring device showing a second embodiment of the present invention.

FIG. 5 is a side sectional view and a front view of the stopper.

FIG. 6 is a front view of a ferrule seen from the optical axis direction showing a conventional example.

FIG. 7 is a side sectional view of an optical connector showing a conventional example.

FIG. 8 is a schematic configuration diagram of an eccentric direction measuring device showing a conventional example.

FIG. 9 is a front view of the eccentricity detection ferrule viewed from the optical axis direction.

FIG. 10 is a front view of the test ferrule seen from the optical axis direction.

[Explanation of symbols]

2 ... Ferrule, 4 ... Split sleeve, 6 ... Split sleeve holder, 8 ... CCD, 10 ... Objective lens, 11 ... Optical fiber, 11a ... Optical fiber core, 12 ... Image processing device, 1
3 ... Light spot image, 14 ... Rotation locus circle, 21 ... Relay lens, 23 ... Split sleeve holder.

Claims (4)

[Claims] 1. A method for measuring an eccentricity of an optical connector for measuring an eccentricity direction of an optical fiber core in an optical connector, wherein a ferrule of the optical connector is held, and light emitted from the optical connector is collected by an objective lens to convert a photoelectric conversion element. In addition to receiving the light, the two-dimensional position of the received light spot image is detected by image processing, and the eccentric direction of the optical fiber core is determined from the positional relationship between the reference point of the eccentric direction and the light spot image. Optical connector eccentricity measurement method. 2. An eccentricity measuring method of an optical connector for measuring an eccentricity direction of an optical fiber core in an optical connector, wherein a ferrule of the optical connector is positioned and grasped in an arbitrary rotational direction in a circumferential direction, and light emitted from the optical connector is an objective. The light is converged by the lens and received by the photoelectric conversion element, and the two-dimensional position of the received light spot image is detected by image processing, and the ferrule of the optical connector is rotated in the circumferential direction to center the rotation locus circle of the light spot image. An eccentricity measuring method for an optical connector, characterized in that the position is obtained and the eccentric direction of the optical fiber core is determined from the positional relationship between the center position and the light spot image. 3. A holding means for positioning and holding the ferrule of the optical connector in an arbitrary rotational direction in the circumferential direction, an objective lens for collecting the light emitted from the optical connector, and receiving the light emitted by the objective lens. An eccentricity measuring device for an optical connector, comprising: a photoelectric conversion element; and an image processing device for detecting a two-dimensional position of a light spot image received by the photoelectric conversion element by image processing. 4. The eccentricity measuring device for an optical connector according to claim 3, further comprising a relay lens that collects light emitted from the optical connector and forms an image at a focal position of the objective lens.