JPS62127665A - Guiding device for ultrasonic wave and light in one end of optical fiber - Google Patents

Abstract

PURPOSE:To guide an ultrasonic wave and light in one end of an optical fiber cable to be measured efficiently by constituting the electrodes, ultrasonic transducer, and converging medium of a fault point searching device for an optical fiber cable by using light transmissive materials. CONSTITUTION:The light-transmissive electrodes 24 and 25 and transducer 26 of a piezoelectric element like LiNbO3 are formed in a curved surface shape, one end of the converging medium 23 such as quartz glass and crystal is connected to an end surface of the optical fiber 22, and the converging medium 23 and the optical fiber 22 of an optical connector 21 are held in one body by a joining member 27. When a high frequency signal is applied between the electrodes 24 and 25, the transducer 26 generates an ultrasonic wave which is converged by the converging medium 23 and guided in the optical fiber 22. The light beam from a laser device is made incident on the optical fiber 22 through the electrode 25, transducer 25, the electrode 24, and converging medium 23, which serves as a lens.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to 5. a failure point search device for searching for a failure point in an optical fiber cable using ultrasonic waves and light. This article concerns an introduction device that introduces ultrasonic waves and light into one end of an optical fiber cable. Search for the failure point of +: 7 Ivacer 7I by using and light -f
In the failure point search device π, v, 1. Measured neck length・τ
It is desirable to introduce ultrasonic waves and light from one end of the tube in order to improve efficiency.

The present invention has been developed in view of the above points, and is based on the combination of ultrasonic waves and light. It is an object of the present invention to provide a device for introducing ultrasonic waves and optical sound into one end of an optical fiber to be efficiently introduced into one end of an optical fiber cable to be measured.

(Means to solve the problem) Therefore, ultrasonic waves and light are used at one end of the optical fiber of the present invention? A device to be introduced includes first and rh second electrodes spaced apart from each other, a transducer disposed between the first and second electrodes, and an ultrasonic wave generated from the transducer. a convergence medium for converging sound waves toward one end of the optical fiber, and the first and second electrode transducers and the convergence medium are made of a light-transmitting material in order to introduce light into the one end of the optical fiber. Alternatively, the first and second electrode transducers are characterized in that a through hole is formed in the focusing medium.

An embodiment of the present invention will be described below with reference to the drawings.

(Embodiment) FIGS. 1(A) and (B) are explanatory cross-sectional views of one embodiment of the present invention, and FIGS. 2(A), (R) to 4(A)
, (El) is a sectional view and an explanatory view of another embodiment of the present invention, FIG.

FIG. 6 is a principle explanatory diagram for explaining that it is possible to search for a fault point in an optical fiber using ultrasonic waves and light.

Before explaining the entire apparatus for introducing ultrasonic waves and optical sound into one end of an optical fiber according to the present invention, it will be explained that a fault point in an optical fiber can be detected using ultrasonic waves and light.

5 and 6 for explaining the principle, when the entire ultrasonic pulse is introduced from one end of the optical fiber 1, the ultrasonic pulse 2 travels through the optical fiber I at its own velocity V as shown in FIG. Propagation in the direction of the arrow shown 1. I'm going to go. From the same end face of the optical fiber l into which the ultrasonic pulse 2 was introduced,
When all the optical pulses are introduced at a certain interval, which is extremely high speed compared to the propagation speed of the ultrasonic pulse 2, a part of the nuclear optical pulse is scattered by the compression wave VC of the preceding ultrasonic pulse 2, n, The light becomes backscattered light and returns to the input end side of the optical fiber 1.

At what time is the ultrasonic pulse 2 introduced into the optical fiber 1?
A light pulse P is incident at time 71.

The total magnitude of the received light level of the backscattered light scattered by the ultrasonic pulse 2 of When the constant interval of n optical pulses incident on the optical fiber IVc is all ΔT.

Time T2 when the next optical pulse P2 is incident on the optical 7-eyeper L
In this case, two preceding ultrasonic pulses are shown in FIG.
It is in a state where it has moved by ΔTV in the direction of the arrow. When there is no discontinuity point such as a break point in the optical fiber 1 through which the ultrasonic pulse 2 propagates, the same propagation state as at time T is maintained in the ultrasonic pulse 2.1. I'm here.

Therefore, the magnitude L of the received light level of the backscattered light scattered by the ultrasonic pulse 2 of the optical pulse P2 incident at time T2
2tri, the magnitude Ll of the light reception level of the previous optical pulse P1
is roughly the same. Similarly, if there is no change in the propagation state of the ultrasonic pulse 2 propagating through the optical fiber t'6, that is, if there is no discontinuous point such as a break point in the optical fiber l, 1. For example, the magnitude of each reception level of the backscattered light scattered by the ultrasonic pulse 2 of the light pulses incident at a constant interval ΔT is the same as shown in FIG. 6. , has continuity.

By the way, as shown in FIG. 5, if a discontinuous point, for example a break point 3, exists in the optical fiber l at a distance Dx from the introduction and incidence end of the ultrasonic pulse and the optical pulse, the break point 3 When the ultrasonic pulse 2 reaches the position, the propagation state of the ultrasonic pulse 2 at this position changes.

Therefore, the magnitude of the received light level Lifl of the backscattered light of the optical pulse Pi incident on the optical fiber at the time when the ultrasonic pulse 2 reaches the breaking point 3 is different from the magnitude of the subsequent received light level, as shown in FIG. As shown in the figure, a step occurs and a discontinuous point occurs. If the incident time of the optical pulse at which this discontinuous point of the received light level occurs is Ti, the propagation speed of the light is much faster than the propagation speed of the ultrasonic wave, and the light travels back and forth from the input end of the optical fiber 1 to the fracture imaginary 3. Since the time required for
The distance Di is calculated using the following formula.

r)i=V(Ti-ηρ Here, vH is the sound velocity of the optical fiber mentioned above, and To is the time when the ultrasonic pulse is introduced.

In this way, an ultrasonic pulse and a light pulse are transmitted from one end of the optical fiber 1, and the backscattered light that is scattered by the ultrasonic pulse of the light pulse and returned is present in the optical fiber depending on the reception level of the backscattered light. It is possible to search for discontinuous points such as breaking points, and the distance to the discontinuous point can be determined using the above equation.

As can be seen from the above description, in a device that searches for all fault points in an optical fiber cable using ultrasonic waves and light, a device that efficiently introduces ultrasonic waves and light from one end of the optical fiber is required.

In FIGS. 1 to 4, 21 is an optical connector, "2
2 is an optical fiber having the entire end face into which ultrasonic waves and light should be introduced; 23 is a convergence medium made of a waveguide member such as quartz glass or crystal; 24.2
5 is an electrode; 26 is a piezoelectric transducer such as ObS or LiNbO3 that generates ultrasonic waves; 2;
7 is a contact member, and 28 is a through hole, which is a passage for the light beam.

The structure Fi'i in Figure 1 has an overall conical shape,
Both the electrodes 24, 25 and the transducer 26 are shaped on curved surfaces. The shape is such that the ultrasonic waves generated from the transducer 26 are converged toward the optical fiber 22 in the most natural manner and with ease due to the ultrasonic energy.

The electrodes 24 and 25 have spherical surfaces centered on the end face of the optical fiber 21 and are spaced apart from each other in the radial direction, and a piezoelectric transformer is connected between the electrodes 24 and 25 to generate ultrasonic waves. A ducer 26 is arranged. The electrode 24 side VC is provided with a convergence medium 23 for converging ultrasonic waves 1 , one end of the convergence medium 23 is connected to the end face of the optical fiber 22 , and the light 7 of the convergence medium 23 and the optical connector 21 is connected by the joining member 27 .
The eyeper 22 is held integrally.

When a high frequency signal is applied between electrodes 24 and 25, ultrasonic waves are generated from transducer 26.

The ultrasonic waves are then focused by the focusing medium 23 and introduced into the optical fiber 22.

FIG. 1(A) At Vc, one electrode 24 and 25. Transducer 26. Both the focusing medium 23 is made of a light-transmitting material that transmits light. Therefore, the light beam from the laser device not shown, that is, the light pulse
Electrode 25. Transducer 26, electrode 24. The light enters the optical fiber 22 via the focusing medium 23. Note that the converging medium 23 also functions as a lens.

On the other hand, in FIG. 1(B), a through hole 28 for allowing the entire light beam to pass along the optical axis extension of the optical fiber 22 is integrally formed in the electrode 25. Transducer 26.
Electrode 24. The convergence medium 23 is perforated. Therefore, a light beam, ie, a light pulse, from a laser device (not shown) enters the optical fiber 22 through the through hole 28. As shown in FIG. 1(B), a through hole 28 is drilled to allow the entire light beam to pass through. Transducer 2 days, be sure to converge medium 23]
The material must also be transparent to light.1. do not have.

FIG. 2 shows a plurality of (for example, five) transducers 26.
This is an example in which In the arrangement of the transducer 2, as shown in FIG. 2(B), there are four transducers 26 around the whole arrangement F-1, and one transducer 26 is also arranged in the center. The number is not limited to five, and the arrangement thereof can be provided as appropriate.

In this embodiment, the net resistance of the transducer can be increased by connecting a plurality of 26 transducer electrodes 24.25 in series. However, since the distances from each transducer 26 to the optical fiber 22 are made equal, the phases of the ultrasonic waves can be easily aligned.

Although the ultrasonic energy can be focused in the same manner as in the case shown in FIG. 1, since the transducer 26 does not have a curved surface, it is easy to manufacture.

Electrodes 24 and 25. Transducer 26. Convergence medium 2
In the same way as in the case of FIG. 1, both of 3 and 3 are made of a light-transmitting material that transmits light and sound. A light beam from a laser device (not shown), ie a light pulse σ, is incident on the transducer 261:)! '825,)
Lancetusa 26, WWi, 24.

The light enters the optical fiber 22 via the convergence medium 23.

Although not shown in FIG. 2, there is an electrode 25. Transducer 2 days.

11 poles 24. Convergence medium 231F-1 All through holes for passing the light beam 1aYl (8), such as optical fiber 2
It is also possible to have a structure in which the holes are drilled on the optical axis extension line of No. 2. For scratches where a through hole is drilled to allow the entire light beam to pass through,
[Camellia 24 and 25. Transducer 26, focusing medium 2
Please make sure that the material is transparent (see Figure 1 (R)).
Similarly, it is not necessary.

FIG. 3 shows a structure in which the curved surfaces of the electrodes 24 and 25 and the transducer 2 shown in FIG. 3 are formed into flat surfaces. Since the transducer 26 is flat, the size of the transducer element can be reduced by several wx (W diameter).
It has the advantage of being easy to manufacture, as it allows you to choose different culms and thicker ones.

Electrodes 24 and 25. Transge User 2nd, Shuto Media 2
The fact that a light-transmitting material that transmits light and sound is used in both cases is similar to the scratch shown in FIG. The light beam of the laser device (not shown), that is, the light pulse, is 5M pole 25
．． Transducer 2F+, @pole 24. Convergence medium 23
The light is incident on the optical fiber 22 through ~.

Although not shown in FIG. 3, there is a fc electrode 25 formed in one piece. Transducer 26° electrode 24
．． The convergence medium 23 may also have a structure in which the through holes for passing the light beam are formed on the extension line of the optical axis of the optical fiber 22, as shown in FIG. 1 (Bl).

In FIG. 4, the focusing medium 23 has the shape shown in FIG.

A structure is adopted in which the ultrasonic waves are introduced into the light beam 22 while converging after reflection 1, as when light is reflected by a concave mirror.

Electrodes 24 and 25. Transducer 26. Convergence medium 2
If a light-transmissive material is used in both cases, the light beam can be incident from the direction of the arrow X in the figure, that is, from the electrode 25 side. At this time, tr pole 25. The optical pulse that has completely passed through the transducer 261M pole 24 is focused on the focusing medium 2
The light beam travels straight to the curved surface 23a shown in FIG. It can also be made to enter from the 23a side.
@ poles 24 and 25. The transducer does not necessarily need to be made of a light-transmitting material.

Although not shown in FIG. 4, there are a through-hole total convergence medium 23VC and an optical fiber 22 for passing the light beam.
It is also possible to have a structure in which the hole is drilled at a position on the extension of the optical axis.

(Effects of the Invention) As described in Explanation 1 above, according to the present invention, the ultrasonic waves generated from the transducer can be efficiently introduced into one end of the optical fiber in a converged form, and at the same time, the light beam can also be introduced into the optical fiber. can be made incident on the same end face of the

[Brief explanation of drawings]

Figures I(A) and (B) are explanatory cross-sections of one embodiment of the present invention. FIG. 5 is a cross-sectional view and a schematic diagram of an embodiment of the present invention. FIG. 6 is a basic explanatory diagram illustrating that it is possible to search for a fault point in an optical fiber by using ultrasonic waves and light. In the figure, 1 is an optical fiber, 2-bar ultrasonic pulse, 3 is a breaking point, 21 is an optical connector, 22-bar optical fiber, 23-bar convergence medium, 24.25 is I! F□fF% 26 is a transducer, 27 is a contact member, and 28 is a through hole.

Claims (2)

[Claims] (1) A device for introducing ultrasonic waves and light into one end of an optical fiber, comprising: first and second electrodes spaced apart from each other; a transducer disposed between the first and second electrodes; and; a focusing medium in which the ultrasonic waves generated from the transducer are focused toward one end of the optical fiber; the first and second electrodes, the transducer, and the focusing medium for introducing light into the one end of the optical fiber; A device that introduces ultrasonic waves and light into one end of an optical fiber whose medium is a light-transmitting material. (2) A device for introducing ultrasonic waves and light into one end of an optical fiber, comprising: first and second electrodes spaced apart from each other; a transducer disposed between the first and second electrodes; and a convergence medium in which the ultrasonic waves generated from the transducer are converged toward one end of the optical fiber; At least one of the media has a through hole for transmitting light,
A device for introducing ultrasonic waves and light into one end of an optical fiber, the other end of which is made of a light-transmitting material.