JPS6270726A - Apparatus for detecting randomness of bundled fiber - Google Patents

Abstract

PURPOSE:To make it possible to quantitatively detect randomness on the basis of quantity of receiving light, by allowing the distance between a gathered end surface and the reflective mirror arranged in opposed relation to said end surface to satisfy a condition shown by a specific formula. CONSTITUTION:The randomness of the arrangement of the optical fiber groups each comprising the same number of fibers respectively constituting one branch 1a and the other branch 1b in the gathered end surface 1c' of a ranched shape bundle fiber 1 branched into at least two fiber groups is detected. That is, a reflective mirror 4 reflecting the light from the gathered end surface 1c' is arranged in opposed relation to said gathered end surface 1c' so as to be separated therefrom by a predetermined distance L and the reflected light from the reflective mirror 4 of the light projected to one branched end surface 1a' from a light source 2 is received by the light receiving element 3 arranged in opposed relation to the other branched end surface 1b'. Randomness is evaluated on the basis of the quantity of receiving light. Herein, the specific distance L is set so as to satisfy a formula d/{2 tan(arcsin NA)}<=L<=D/{4 tan(arcsin NA)} wherein the bundle diameter of the gathered end is set to D, an optical fiber core diameter to (d) and the number of openings of the optical fiber to NA.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention is directed to the randomness of the arrangement of a large number of optical fibers constituting the bundle fiber at the collective end face of a branched fiber bundle branched into at least two parts. That is, it relates to a bundle fiber randomness detection device for detecting randomness.

<Prior Art> Conventionally, for example, in a bundle fiber IO branched into two as shown in FIG. 9, a large number of optical fibers constituting the bundle fiber IO are arranged uniformly near the collective end 10c. Corner fiber and other branch 10b
To test the randomness of whether the optical fibers constituting the are uniformly arranged near the collective end 10c,
Since the inspection is carried out by photographic judgment of the cross section of the clustered end, the inspection results vary depending on the judgment of the inspector, resulting in poor reliability. In addition, FIG. 8 (A XB ) shows cross-sectional views of the collective end when there is no randomness and when there is large randomness.

<Problems to be Solved by the Invention> The present invention has been made in view of the above-mentioned points. The purpose of this invention is to quantitatively detect the randomness of the arrangement of optical fibers constituting one fiber and the other branch.

<Means for Solving the Problems> In order to achieve the above-mentioned object, the present invention includes a plurality of optical fibers constituting one branch at a collective end face of a branched bundle fiber branched into at least two parts; A bundle fiber randomness detection device for detecting randomness in the arrangement of a large number of optical fibers constituting another branch, the device being arranged opposite to one branch end face,
A light source for projecting light from this branch end face, a light receiving element that is placed opposite to the other branch end face and receives the reflected light from this branch end face, and a light receiving element that is placed opposite to each other at a predetermined distance from the collective end face. A reflecting mirror is provided to reflect light from the collective end face, and the randomness is evaluated based on the scene received by the light receiving element, and the predetermined distance is determined by the amount of light received and the randomness. The following settings are made to ensure a positive correlation. i.e., a bundle of collective ends.

If the diameter is D, the optical fiber core diameter is d1, and the numerical aperture of the optical fiber is NA, then d/(2tan(arcsinN A month≦L≦D/
(4tan(arcsi-nNA)).

<Operation> Since the present invention is configured as described above, it is possible to obtain a positive correlation between the amount of received light and randomness, and it is possible to detect randomness based on the amount of received light. It becomes possible.

<Example> Hereinafter, an example of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram for explaining the present invention in detail. The randomness detection device of the present invention comprises at least two
End face 1 of gathering part 1c of bundle fiber 1 branched into
One branch in c'! This is to detect the uniformity, that is, the randomness, of the arrangement of the same number of optical fibers constituting each of the branch a and the other branch 1b.

This detection device includes a light emitting diode 2 as a light source disposed facing one branch end face 1a'' of a bundle fiber 1, a photodiode 3 as a light receiving element disposed facing the other branch end face 1b', and a bundle fiber 1. A reflecting mirror 4, which is a reflecting member, is disposed facing the collective end surface 1c' of the mirror 1 with a predetermined distance therebetween.

In this detection device, a light emitting diode 2 emits light to one branch end face 1a', this light passes through a bundle fiber 1 and is reflected by a reflecting mirror 4, and this reflected light passes through the bundle fiber 1 again to the other branch end face 1a'. The light is applied to the photodiode 3 from the end face 1b.

In the present invention, the light m received by this photodiode 3
By detecting the randomness of the arrangement of the optical fibers at the collective end face 1c', the predetermined distance between the collective end face 1c' and the reflecting mirror 4 must be set as follows. Must be set to .

d/ (2tan(arcsinNA)}≦L≦D
/ (4tan(arcsi-nNA)) Here, D is the bundle diameter of the collective end 1c, d is the diameter of the optical fiber core constituting the bundle fiber 1, and NA is the numerical aperture of the optical fiber.

Next, the reason for setting the predetermined distance as described above will be explained in detail below.

First, ■, ≦D / (4tan(arcsinN A
)) will be explained. Now, for example, as shown in FIG. 2, there is a group of optical fibers 5 whose collective end faces 1c' are continuous with the light emitting branch 1a indicated by diagonal lines, and the light receiving branch 1b.
Let us consider the case where there is almost no randomness that clearly distinguishes the remaining optical fiber group 6 that continues from the . In this case without randomness, the weight of reflected light incident on the bundle fiber 1 from the reflection mirror 4 must be suppressed compared to the case with randomness, and as in the case with randomness, the weight of reflected light entering the bundle fiber 1 must be suppressed. Reflected light must not be incident.

Therefore, the path of the reflected light in the case of FIG. 2 without this randomness will be explained with reference to FIG. 3. In FIG. 3, θ-arcsinNA, and the distance ML is the distance at which the light from the light projection branch 1a enters the boundary between the optical fiber group 5 and the optical fiber group 6, and this distance is As is clear from the figure, I, = D / (4tan(arcsinNA)
)・−・−(1).

If this distance becomes larger than the value of equation (1), for example, distance L1, as is clear from FIG. 3, the light will enter the optical fiber group 6 for light reception, and the amount of light received will increase. Resulting in. In other words, even though there is no randomness, the number of light-receiving scenes increases in the same way as when there is randomness. In the case of no randomness, the amount of reflected light incident on the bundle fiber l from the reflection mirror 4 is
As mentioned above, since the randomness must be suppressed compared to the case where there is randomness, the distance between the reflecting mirror 4 and the collective end face lc' must be equal to or less than the value of the above equation (1). Therefore, L≦D/(4tan(arcsinNA)).

Next, d/(2tan(arcsinNA)}≦L
I will explain about it. Now, let us consider the case where the randomness is large, that is, the case where the optical fibers continuous to the light emitting branch 1a and the optical fibers continuous to the light receiving branch 1b are arranged uniformly at the collective end. In this case, the light from each light-emitting optical fiber must be reflected by the reflecting mirror 4 and input into the adjacent light-receiving optical fiber. FIG. 4 is a diagram for explaining the path of the reflected light at this time. In FIG. 4, d is the fiber outer diameter of the optical fiber constituting the bundle fiber 1, and θ= ar
csinNA, and the distance is the distance at which the light from the light projection optical fiber I2 enters the boundary of the light projection optical fiber 12, and as is clear from the figure, this distance is 1, =d/(2tan(arcsinNA))−
-----(2).

If this distance becomes smaller than the value shown by equation (2), for example, the distance L2, the light from the light projection optical fiber 12 is reflected by the reflection mirror 4 and the light from the light projection optical fiber 12 is reflected by the reflection mirror 4. The light enters the optical fiber 12 and is no longer received by the light-receiving optical fiber. In other words, even though the randomness is large, the number of light-receiving scenes decreases, and the result is the same as when there is no randomness. Therefore, the distance between the reflection mirror 4 and the collective end surface 1c' must be equal to or greater than the value of the above equation (2), and d/(2tan(arcsinNA)}≦L.

In this way, when there is no randomness, the amount of received light is small, and when there is randomness, there is a positive correlation between the amount of received light and randomness, as described later. Therefore, randomness can be detected based on the amount of received light.

Next, 400 multicomponent glass fibers with an outer diameter of 50 μmφ and a numerical aperture NA=0.5 were bundled, and the bundle diameters of the branch ends la and 1b were set to I and l mmφ, and the bundle diameter of the collective end 1c was set to 1.6 mmφ. FIG. 5 shows the relationship between the amount of light received by the photodiode 3 and the randomness when the distance from the reflecting mirror 4 to the collective end face is 0.5 mm.

As is clear from FIG. 5, a positive correlation is obtained between the received light scene and the randomness. Therefore, it is possible to quantitatively detect randomness based on the amount of received light.

In addition, under the conditions shown in Fig. 5, the distance limit is 0.05/{2tan30°)=0.04≦L≦1,6
/{4tan30°)=0.69, and if the distance is out of this range, the correlation between the amount of received light and the randomness will collapse. Figure 6 shows one implementation of the present invention based on the above principle. FIG. 2 is a front view of an example detection device. In this detection device 9 of FIG. 6, as shown in FIG.
Randomness can be detected not only in the bundle fiber 1 that is simply branched into two, but also in the collective ends 8 d and 8 e of the bundle fiber 8 that is branched in a substantially W-shape as shown in FIG. It is configured. When detecting the randomness of the bundle fiber 8 in FIG.
The branches 8a and 8c for light reception are connected to the connection terminals 9' and 11 of the detection device 9, the branch 8b for light emission is connected to the connection terminal 1 (1'), and the collective end facing the reflecting mirror is connected to the connection terminal 1 (1'). 8
Connect terminals d and 8e to connection terminals 12' and 13.

As a result, light is projected from the branch 8b and reaches the gathering end 8d.

The light reflected by the reflection mirror via 8e is branched to 8g.

The light is applied to the light receiving element from 8c, and randomness at the collective ends 8d and 8e is detected based on the amount of received light.

<Effects of the Invention> As described above, according to the present invention, a light source is disposed facing one branch end face for emitting light from the branch end face, and a light source is disposed facing the other branch end face for emitting light from the branch end face. A light-receiving element that receives reflected light and a reflecting member that is disposed facing each other at a predetermined distance from the collective end face and that reflects the light from the collective end face are provided, and the predetermined distance is the bundle of the collective end. If the diameter is D1, the optical fiber core diameter is d1, and the numerical aperture of the optical fiber is NA, then d/(2tan(arcsinNA)}≦L≦D
/ (4tan(arcsi-nNA)), the relationship between the light scattering received by the light receiving element and the randomness is a positive correlation, and therefore, based on the amount of light received, Randomness can be detected quantitatively, and reliability is improved compared to conventional examples.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram for explaining the present invention in detail, Fig. 2 is a diagram schematically showing the collective end face when there is no randomness, and Fig. 3 is the path of reflected light in the state shown in Fig. 2. FIG. 4 is a diagram showing the path of reflected light in a state where randomness is large. FIG. 5 is a characteristic diagram showing the relationship between the amount of received light and randomness in the present invention. FIG. 7 is a front view of the detection device of the embodiment, FIG. 7 is a plan view of the bundle fiber, FIG. 8 is a sectional view of the bundle fiber showing the difference in randomness, and FIG. 9 is a plan view of the bundle fiber. 1.8... Bundle fiber, Ia... One branch, 1b... Other branch, 1c... Collective end, 2...
Light emitting diode, 3... Photodiode, 4...
reflective mirror.

Claims (1)

[Claims] (1) For detecting randomness in the arrangement of a large number of optical fibers constituting one branch and a large number of optical fibers constituting the other branch at a collective end face of a branched fiber bundle branched into at least two parts. A bundle fiber randomness detection device that includes a light source that is placed opposite to one branch end face and emits light from this branch end face, and a light source that is placed opposite to the other branch end face to receive reflected light from this branch end face. a light-receiving element disposed opposite to each other at a predetermined distance L from the collective end surface,
and a reflecting member that reflects light from the collective end face, and evaluates randomness based on the amount of light received by the light receiving element, and the predetermined distance L is a bundle diameter of the collective end D, If the optical fiber core diameter is d and the numerical aperture of the optical fiber is NA, then d/{2tan(arcsinNA)}≦L≦D/{4
tan(arcsi-nNA)} A bundle fiber randomness detection device.