JPH05333241A - Method for measuring dimension of optical optical parts - Google Patents

Abstract

PURPOSE:To provide the method for measuring the dimensions of optical parts which can suppress the errors on the positions of the centers of pin holes and, therefore, makes it possible to obtain the central positions of the respective fiber insertion holes on the basis of the positions of the pin holes with high accuracy. CONSTITUTION:The positional relations between the centers of the pin holes 4c of the optical parts 4 having the pin holes 4c, 4c and multiple fibers 6 and the centers of the respective optical fibers of the multiple fibers 6 are determined by inserting single-fiber ferrules 8 mounted with optical fibers 9 in the pin holes 4c and measuring the centers of the optical fibers 9 of the single-fiber ferrules 8 and the respective optical fibers of the multiple fibers 6. The dimensions are measured by maintaining the spacings between the single-fiber ferrules 8 to be inserted into the pin holes 4c of the optical parts 4 and the pin holes 4c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring dimensions of optical components such as multi-core connectors.

[0002]

2. Description of the Related Art An optical component used for butt connection of optical fibers, for example, a multi-core connector, has a plurality of fiber insertion holes formed in a plastic ferrule at a certain arrangement pitch and positioning for butt connection. And a pair of pin holes through which the guide pins are inserted. In this multi-core connector, each optical fiber of the multi-core fiber is inserted into each of the plurality of fiber insertion holes, and these are fixed by an adhesive, and the guide pin is connected to the pin hole of the other multi-core connector. By fitting them so as to span them, they are butt-connected with other multi-core connectors.

Here, as the optical connector, there is also a single-core connector in which a single-core fiber is inserted and fixed in a fiber insertion hole of a plastic ferrule. In such an optical connector, it is necessary to precisely form and process each fiber insertion hole in a submicron order in order to reduce connection loss due to butt connection with another optical connector as much as possible. For this reason,
For the purpose of quality control of the optical connector, dimensional measurement is performed to inspect the center position of each fiber insertion hole based on the position of the pin hole in the optical connector.

As a method for measuring such a dimension, for example, Japanese Patent Application No. 2-321847 discloses a dimension measuring method for a multi-core connector. In this method, a single-core ferrule is inserted into the pin hole of the multi-core connector, each optical fiber of the multi-core fiber attached to the multi-core connector and the optical axis center of the optical fiber of the single-core ferrule are measured, and the pin hole is measured. And the positional relationship of the centers of the optical fibers of the multi-core fiber. This measurement method allows the optical connector to be put into a mating condition for actual use, and the correlation between the axial misalignment amount and the connection loss between the corresponding optical fibers due to butt splicing can be correlated to make it more usable. It is possible to perform evaluation in a close state.

[0005]

By the way, in the dimension measuring method of the multi-core connector described above, the center position of the pin hole into which the guide pin is fitted is determined as the reference position to be fitted with another multi-core connector. In addition, the single-core ferrule is inserted into the pin hole, and the position of the optical fiber of the single-core ferrule is determined as the center of the pin hole.

In order to perform such dimension measurement with high accuracy, it is necessary that the center of the single-core ferrule and the center of the pin hole are coincident with each other. However, between the pin hole and the single-core ferrule. Has a slight gap due to the insertion of the single-core ferrule. For this reason, since the center of the pin hole and the center of the single-core ferrule do not coincide with each other, an error occurs in the obtained position of the pin hole center, and thus an error also occurs in the obtained position of the optical axis center of the optical fiber. This is a problem common not only to the multi-core connector, but also to optical components that mutually connect optical fibers or optical waveguides or optical fibers and optical waveguides by butt-connecting each other.

The present invention has been made in view of the above points, and an error relating to the position of the center of the pin hole can be suppressed to a small level. Therefore, the center position of each fiber insertion hole based on the position of the pin hole is high. It is an object of the present invention to provide a dimension measuring method for an optical component which can be obtained with accuracy.

[0008]

According to the present invention, in order to achieve the above object, a single-core ferrule having an optical fiber attached to the pin hole is inserted into an optical component having a pin hole and a multicore fiber. Then, by measuring the optical fibers of the single-core ferrule and the centers of the optical fibers of the multi-core fiber, the dimensions of the optical component for determining the positional relationship between the center of the pin hole and the center of each optical fiber in the multi-core fiber In the measurement method, the dimension is measured by keeping the gap between the single-core ferrule inserted into the pin hole of the optical component and the pin hole at a predetermined distance or less.

[0009]

If the gap between the single-core ferrule and the pin hole is maintained at a predetermined distance or less, the measurement accuracy regarding the position of the pin hole is improved, and therefore the measurement accuracy regarding the center of each optical fiber of the obtained multi-core fiber is also improved. improves.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the method of the present invention is applied to a multi-core connector will be described in detail below with reference to FIGS. FIG. 1 shows the configuration of a dimension measurement system for carrying out the method of the present invention,
The dimension measurement system includes an XY stage 1, a scale 2 and a support frame 3.

As shown in the figure, the XY stage 1 has a rectangular mounting hole 1a formed at the center thereof so as to vertically penetrate therethrough and to which an optical component to be measured, for example, the multi-core connector 4 is mounted. The XY stage 1, together with the multi-core connector 4 mounted in the mounting hole 1a, can be finely moved in the directions of arrows X and Y in the drawing, and is moved in the two directions of X and Y by the stage controller 5 shown in FIG. It Thereby, the multi-core connector 4 is
The position in the X and Y directions is finely adjusted.

The multi-core connector 4 is, as shown in FIG.
The multi-core fiber 6 is attached to the main body 4a, one end of each optical fiber 6a is exposed at the butt end face, and the other end of the multi-core fiber 6 is connected to a light source 7 using an LED (see FIG. 2). Has been done. Further, pin holes 4c, 4c are formed on both sides of the main body 4a where the ends of the respective optical fibers 6a are exposed,
A single-core ferrule 8 is detachably inserted into each pin hole 4c.

The single-core ferrule 8 is for measuring the center position of the pin hole 4c, and there is a gap between the pin hole 4c and the pin hole 4c so that the center position of the pin hole 4c can be measured with high accuracy. Use the one having a diameter of 0.2 μm or less. This single-core ferrule 8 is attached to one end of an optical fiber 9,
The other end of the optical fiber 9 is connected to the light source 7. The scale 2 is for measuring the moving position of the XY stage 1 which is finely moved in the XY direction by mounting the multi-core connector 4, and the position in the XY direction is adjusted by the scale controller 10 shown in FIG. However, when the multicore connector 4 is measured, the positioning to the initial position is performed.

The support frame 3 is provided with a transmitting / receiving ferrule 11
1 is attached and supported, and as shown by an arrow Z in FIG. 1, it is moved in a direction orthogonal to the plane defined by the XY stage 1 to project the transmitting / receiving ferrule 11 from the multicore connector 4. To match. The light transmitting / receiving ferrule 11 is attached to the other end of the light transmitting / receiving fiber 13 whose one end is connected to the optical power meter 12 (see FIG. 2). The optical fiber 6a of the core fiber 6 or the optical fiber 9 of the single-core ferrule 8 is optically connected.

The optical power meter 12 comprises a light transmitting / receiving fiber 1.
The intensity of the measuring light from the light source 7 transmitted from the light source 3 is measured. The intensity of the measurement light measured by the optical power meter 12 is converted into a predetermined optical signal and input to the computer (ECU) 14. The computer 14, as shown in FIG.
It is connected to the stage controller 5, the light source 7, the scale controller 10, and the optical power meter 12 to control their operations, and determine the position where the light intensity is maximum based on the input optical signal relating to the measurement light.

In the method for measuring the size of an optical component of the present invention, the size of a multi-core connector is measured as follows using the above measuring system. First, in each pin hole 4c of the multi-core connector 4,
A single-core ferrule 8 so that it is substantially flush with the butt end face 4b.
Insert. At this time, the single-core ferrule 8 has the pin hole 4
Use a material having a clearance of 0.2 μm or less with respect to c.

Next, the multi-core connector 4 is connected to the XY stage 1.
The support frame 3 is lowered while being attached to the attachment hole 1a. As a result, the transmitter / receiver ferrule 11 is butted to the butted end face 4b of the multi-core connector 4, and the first optical fiber of the plurality of optical fibers 6a and 9 for which the position of the center of the optical axis is to be obtained is sent / received to the fiber 13 Butt connection.

At this time, the light-transmitting / receiving ferrule 11 does not need to be completely brought into close contact with the multi-fiber connector 4, and the multi-fiber connector 4 can be used while measuring the measurement light from a predetermined optical fiber.
It suffices that the interval between and is kept constant. In this manner, the optical power meter 12 measures the intensity of the measurement light transmitted from the light transmitting / receiving fiber 13 in a state where the multi-fiber connector 4 and the light transmitting / receiving ferrule 11 are roughly connected.

In this measurement, the XY stage 1 is moved in an arbitrary direction within the range of the first optical fiber, and the intensity of the measurement light measured by the optical power meter 12 is maximum, that is, the transmission loss is reduced. The minimum position is read by the scale 2 based on the determination result by the computer 14, and this position is set as the optical axis center of the first optical fiber. Hereinafter, similarly, the positions of the other plurality of optical fibers 6a and 9 corresponding to the optical axis centers of the second to nth optical fibers are obtained. Then, based on these measurement results, a plurality of optical fibers 6a with one of the pin holes 4c of the multi-core connector 4 as a reference.
The position of is required with high accuracy.

Here, in an optical connector in which pin holes and optical fibers are arranged with high accuracy, a major part of connection loss when they are butt-connected to each other is due to axial misalignment between optical fibers. Therefore, based on the above measuring method, the dimensions of the two multicore connectors 20 and 21 shown in FIG. 3 that are butt-connected to each other were measured, and the quality of the measurement results was evaluated as follows.

That is, first, based on the result of the above-mentioned dimension measurement, the virtual axial deviation amount of each corresponding optical fiber of both multi-core connectors was obtained. Here, the multi-core connector 20 is the main body 2
One end of a multi-core fiber (not shown) is attached to 0a, and one ends of four optical fibers 22 constituting the multi-core fiber are exposed at the butt end face 20b. Also, the main body 20
Pin holes 20c, 20c are formed on both sides of a.
On the other hand, since the multi-fiber connector 21 has one end of the plurality of optical fibers 23 exposed at the butt end face 21b and has the same structure as the multi-fiber connector 20, a description corresponding to the corresponding parts in the drawings will be given. To do.

Here, the virtual axis shift amount was obtained as follows. That is, in each multi-core connector 20, 21,
As shown, the pin holes 20c, 20c and the pin holes 21c,
And each X ₁ axis and X ₂ axis line indicating the center of 21c was as arrows as X-axis of the reference pin holes 20c, 20c and pin holes 21c, the centers of 21c bisects, each X _1, X Lines shown by arrows orthogonal to the _two axes were used as the reference Y-axis and the Y ₁ -axis and the Y ₂ -axis, respectively.

Now, based on the position of each optical fiber 22 obtained by the dimension measurement of the multi-core connector 20, the positions of the four optical fibers 22 are displayed in coordinates with reference to the X ₁ axis and the Y ₁ axis. 4, as shown in FIG.
The coordinates of the first and fourth optical fibers 22 of (x _11,
y ₁₁ ), (x _14, y ₁₄ ). In addition, the multi-core connector 21
Similarly, as shown in FIG. 5, the coordinates of the second and third optical fibers 23 are (x _22, y ₂₂ ), (x
_23, y ₂₃ ).

The multi-core connector 20 thus determined,
Based on the coordinate positions of the optical fibers 22 and 23 of 21, the multi-core connectors 20 and 21 are arranged so that the directions of the X ₁ axis and the X ₂ axis are the same and the directions of the Y ₁ axis and the Y ₂ axis are different from each other. Assuming that they have been butt-connected (hereinafter, this connection is referred to as “forward connection”), the corresponding optical fibers 22 and 23
Has a positional relationship as shown in FIG.

In the state where the multi-core connectors 20 and 21 are connected in this way, the distance between the corresponding optical fibers is defined as the virtual axis deviation amount d (μm), and as shown in FIG. The virtual axis deviation amounts between the two are set to d _{1 to} d ₄ , respectively. Therefore, for example, the virtual axis shift amount d ₁ of the first optical fibers 22 and 24 is given by the following equation. _{d 1 = {(x 21 -x} 11) 2 + (Y 21 -Y 11) 2} 1/2 On the other hand, unlike the direction of the X ₁ axis and X ₂ axes mutually, the direction of the Y ₁ axis and Y ₂ axis In the case of butt connection so as to be in the same direction (hereinafter, this connection is referred to as "reverse connection"), the order of the optical fibers to be connected is reversed, and for example, the coordinate (x
_The optical fiber 22 located at _11, y ₁₁ ) has coordinates (x _24,
an optical fiber 23 of y _24), the coordinates (x _14, optical fiber 22 of y _14), the coordinates (x _21, y ₂₁₎ of the optical fiber 23
And are connected respectively. However, even in this case, the virtual axis shift amount d is given by the above equation.

Then, the virtual connection loss L _i based on the virtual axis shift amount d can be obtained by the following equation. L _i = 4.343 × [d / ω (λ)] ² where the above equation is BSTJ Vol.56, No.5, May-June
Based on the analysis described in 1977, P.703-718,
(Λ) is the mold field radius. In the above formula regarding the virtual connection loss L _i , the measuring field having a wavelength of 1.3 μm is used, and the mold field radius ω (λ) at that time is used.
Is 4.65, the virtual connection loss L _i is given by the following equation.

L _i = 0.20 × d _i ² Next, the connection loss measured using the dimension measuring system is L _r
And δ = | L _r −L as a standard for evaluating the measurement accuracy.
Consider the loss difference δ represented by _i |. At this time, in the dimension measurement for the two multi-core connectors 20 and 21 shown in FIG. 3, nine clearance gaps C are set between the pin holes 20c and 21c and the single-core ferrules that are inserted into the pin holes 20c and 21c, respectively. Then
The virtual connection loss L _i and the connection loss L _r were obtained by the above method, and the relationship between the gap C and the loss difference δ was obtained. The results are shown in FIG. 7 with the vertical axis representing the loss difference δ (dB) and the horizontal axis representing the gap C (μm). In the figure, + is the maximum value of the loss difference δ, and □ is the root mean square value (σ) of the loss difference δ.

As is apparent from FIG. 7, the gap C is 2 μm.
Within the range, the loss difference δ is always within 0.2 dB, and the mean square value (σ) of the loss difference δ when the gap C is 2 μm is 0.0.
It was about 7 dB, which was sufficiently practical. On the other hand, it has been found that when the gap C is larger than 2 μm, a large loss difference δ occurs, and the absolute accuracy of the measurement cannot be guaranteed.

Next, the multi-core connectors 20, 21 shown in FIG.
3 sets of 1st to 3rd are prepared, and each pin hole 20c, 21c
A single-core ferrule was inserted into the to measure the dimensions and the connection loss (including normal connection and reverse connection). Based on these measurements, the virtual axis deviation amount d (μm) obtained for a total of 24 samples of the optical fibers 22 and 23 connected to each other
And the connection loss value L (dB) are shown in FIGS. 8 and 9. At this time, the clearance C between each pin hole 20c, 21c and the single-core ferrule inserted in these pin holes is set to 0.4 μm in the case of FIG. 8 and 2.0 μm in the case of FIG. It was measured.

In FIGS. 8 and 9, ◯ indicates a first multicore connector set, Δ indicates a second multicore connector set, and X indicates a third multicore connector set. When the correlation coefficient between the virtual axis deviation amount d and the connection loss value L was calculated based on the results shown in FIG. 8, a high correlation coefficient of 0.8 or more was obtained, and highly accurate dimension measurement was possible. I found out.

On the other hand, when the correlation coefficient between the virtual axis deviation amount d and the connection loss value L was similarly obtained based on the results shown in FIG. 9, the correlation coefficient was about 0.5 and the error was ±. It was within the range of about 0.1 dB. As is clear from the above explanation,
According to the dimension measuring method of an optical component of the present invention, the center of each optical fiber core, that is, the center position of each fiber insertion hole, with reference to the position of the pin hole can be obtained with high accuracy.

Further, the virtual connection loss value L _i can be estimated from the virtual axis deviation amount d obtained from the dimension measurement of the multi-core connector. Further, it is also possible to predict the actual connection loss when the multi-core connectors are butt-connected to each other from the estimated virtual connection loss value L _i , and further, the virtual connection loss value L _i and the measured connection loss value L _i. It can also be used to evaluate the connection loss measurement accuracy and the connection loss measurement accuracy.

[0033]

As is apparent from the above description, according to the optical component size measuring method of the present invention, the error regarding the position of the center of the pin hole is suppressed to a small level, and each fiber is inserted based on the position of the pin hole. It has an excellent effect that the center position of the hole can be obtained with high accuracy.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a mechanical configuration of a dimension measuring system for carrying out the method of the present invention.

FIG. 2 is a schematic connection diagram of the dimension measuring system of FIG.

FIG. 3 is a layout drawing of a multi-core connector used to evaluate the quality of the measurement accuracy of the method of the present invention.

FIG. 4 is an array diagram showing an array of measured optical fibers of the first multi-core connector.

FIG. 5 is an array diagram showing an array of measured optical fibers of the second multi-core connector.

FIG. 6 is an array diagram in which the array diagrams of FIGS. 4 and 5 are overlapped.

7 is a characteristic diagram showing a relationship between a loss difference δ (dB) obtained by using the multi-core connector shown in FIG. 3 and a clearance C (μm) between a pin hole and a single-core ferrule inserted in the pin hole. Is.

8 is a correlation diagram showing a correlation between a virtual axial displacement amount based on the center position of an optical fiber obtained by the method of the present invention using the multi-core connector shown in FIG. 3 and a connection loss.

FIG. 9 is a correlation diagram showing a correlation between an imaginary axis shift amount obtained based on a conventional dimension measuring method and a connection loss.

[Explanation of symbols]

 1 XY stage 4 Multi-core connector (optical component) 4c Pin hole 6 Multi-core fiber 6a Optical fiber 8 Single-core ferrule 8a Optical fiber 11 Transmitting / receiving ferrule 12 Optical power meter 13 Transmitting / receiving fiber 20,21 Multi-core connector (optical) Parts) 20c, 21c Pin hole 22, 23 Optical fiber

Claims (1)

[Claims] 1. An optical component having a pin hole and a multi-core fiber, wherein a single-core ferrule having an optical fiber attached to the pin hole is inserted and attached, and each of the optical fiber of the single-core ferrule and the multi-core fiber. In a dimension measuring method of an optical component, which measures the center of the optical fiber to determine the positional relationship between the center of the pin hole and the center of each optical fiber in the multicore fiber, a single core inserted into the pin hole of the optical component. A dimension measuring method for an optical component, characterized in that a dimension between the ferrule and the pin hole is maintained at a predetermined distance or less for dimension measurement.