JP3718690B2 - Optical magnetic field sensor and optical magnetic field detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical magnetic field sensor and an optical magnetic field detection apparatus that acquire magnetic field information with high accuracy from a low frequency band to a high frequency band.
[0002]
[Prior art]
In recent years, with the development of electronic devices, it has become necessary to measure a magnetic field leaking from an integrated circuit board or the like with high accuracy. As a conventional magnetic field sensor for acquiring magnetic field information, for example, a so-called double loop magnetic field sensor 110 in which two loops made of a conductive material are formed adjacent to each other as shown in FIG. The magnetic field detection device used is known. (For example, see Non-Patent Document 1)
[0003]
In this double-loop magnetic field sensor 110, the magnetic signal detected by the double loop 112, which is two loops, receiving a magnetic field is transmitted to the measuring device via the metal transmission line. In other words, this magnetic field signal is once transmitted from the double loop 112 through the coplanar line 114 shown in FIG. 5, and after passing through a balun (not shown) that performs balanced / unbalanced conversion, the magnetic field signal is further transmitted to the measuring instrument side by the coaxial cable. Was. And the magnetic field signal transmitted with these coplanar lines 114 and a coaxial cable which are metal transmission lines was measured with this measuring machine, and the detection result was obtained.
[0004]
[Non-Patent Document 1]
1989 Microwave Theory and Techniques-International Microwave Symposium Digest Volume 2, 823-825 (SSOsofsky and SESchwartz, 1989 IEEE MTT-Int. Microwave Symp. Digest, vol. 2, pp823-825)
[0005]
[Problems to be solved by the invention]
However, in the above-described double loop magnetic field sensor 110, not only the metal transmission line made of metal disturbs the electromagnetic field of the measurement target site itself, but also in the GHz band, which is a high frequency band. As a result that the transmission line is affected by the noise caused by the surrounding electric field and the detection accuracy is lowered, it is difficult to measure the magnetic field with high accuracy.
[0006]
Further, in such a GHz band, it becomes difficult to perform balanced / unbalanced conversion in a balun that is a connection portion between the coplanar line 114 and the coaxial cable, and high-precision measurement data cannot be transmitted, resulting in high measurement accuracy. There were also disadvantages that were further reduced. That is, the conventional magnetic field detection apparatus cannot perform high-precision measurement of the magnetic field in a high frequency band such as the GHz band.
In view of the above facts, an object of the present invention is to provide an optical magnetic field sensor and an optical magnetic field detection device capable of acquiring magnetic field information with high accuracy from a low frequency band to a high frequency band.
[0007]
[Means for Solving the Problems]
A magneto-optical sensor according to claim 1 is a pair of conductor patterns each formed in a ring shape by a conductive material and arranged adjacent to each other so that a part thereof is shared, and a gap is formed in the connection part,
An electro-optic crystal inserted into a gap formed in a connection portion of the pair of conductor patterns;
It is characterized by having.
[0008]
According to the magneto-optical sensor according to claim 1, a pair of conductor patterns each formed in a ring shape with a conductive material in a form in which a part is shared and connected are arranged adjacent to each other, and the pair of conductor patterns The electro-optic crystal is inserted into the gap formed in the connection portion. Therefore, when this optical magnetic field sensor is disposed as a sensor body at a measurement target location and light such as laser light is passed through the electro-optic crystal, a magnetic field detected and acquired by a pair of conductor patterns forming a double loop Information can be converted into an optical signal using the electro-optic effect of the electro-optic crystal.
[0009]
Accordingly, the magneto-optical sensor according to this claim can transmit magnetic field information by an optical signal using light such as laser light without using a metal transmission line such as a coaxial cable, and the metal portion is only a conductor pattern. Therefore, the electromagnetic field around the measurement target portion to be measured is less likely to be disturbed.
[0010]
In particular, in the high frequency band, since light is used, there is no possibility that the electrical signal is affected by noise caused by the surrounding electric field in the middle of passing through the transmission path, and the detection accuracy is not lowered. Similarly, since light is used, there is no need for balanced / unbalanced conversion, and there is no decrease in detection accuracy due to imperfect balance / unbalanced conversion.
[0011]
As a result of the above, according to the optical magnetic field sensor of the present invention, it is possible to measure a magnetic field with high accuracy from a low frequency band to a high frequency band and to transmit magnetic field information with high accuracy. As a result, magnetic field information can be acquired with high accuracy.
[0012]
The magneto-optical sensor according to claim 2 has a configuration in which the electro-optic crystal is formed of lithium niobate or lithium tantalate in addition to the configuration similar to that of the magneto-optical sensor of claim 1. . That is, by using lithium niobate or lithium tantalate as the electro-optic crystal, the effect of claim 1 can be achieved more reliably.
[0013]
According to the magneto-optical sensor according to claim 3, in addition to the same configuration as the magneto-optical sensor of claim 1 and claim 2, the pair of conductor patterns are respectively formed in an annular shape having the same shape in the plane. It has a configuration that. In other words, since the pair of conductor patterns having the same shape are formed two-dimensionally in one plane, the magnetic field can be obtained simply by arranging the plane perpendicular to the direction of the magnetic flux. Information can be acquired easily and more accurately.
[0014]
The optical magnetic field detection device according to claim 4 comprises a light source that generates light,
A pair of conductor patterns each formed in an annular shape by a conductive material and arranged adjacent to each other so that a portion thereof is shared and a gap is formed in the connecting portion;
An electro-optic crystal that is inserted into a gap formed in a connection portion of the pair of conductor patterns and through which light from a light source can pass;
A light detection member for detecting the state of light passing through the electro-optic crystal;
It is characterized by having.
[0015]
According to the optical magnetic field detection device according to claim 4, a pair of conductor patterns each formed in a ring shape by a conductive material in a form in which a part is shared and connected are arranged adjacent to each other, and the pair of conductors An electro-optic crystal is inserted in a gap formed in the connection portion of the pattern. And the light from the light source which generate | occur | produces light passes this electro-optic crystal, and a photon detection member comes to detect the state of this passed light.
[0016]
That is, in the optical magnetic field detection device according to the present invention, similarly to the first embodiment, an electro-optic crystal is inserted into the gap formed at the connection portion of the pair of conductor patterns, and laser light from a light source is inserted into the electro-optic crystal. By passing light such as, it is possible to convert magnetic field information detected and acquired by a pair of conductor patterns forming a double loop into an optical signal using the electro-optic effect of the electro-optic crystal.
[0017]
Accordingly, in the optical magnetic field detection device according to the present invention, the light detection member detects the state of light from the light source that has passed through the electro-optic crystal. Since only the conductor pattern is used, high-accuracy measurement can be performed in the same manner as in claim 1 because the electromagnetic field around the measurement target portion to be measured is less likely to be disturbed.
[0018]
As described above, according to the optical magnetic field detection device of the present invention, it is possible to measure a magnetic field with high accuracy from a low frequency band to a high frequency band as in the case of claim 1, and to detect magnetic field information with high accuracy. As transmission becomes possible, magnetic field information can be acquired with high accuracy.
[0019]
According to the optical magnetic field detection apparatus according to claims 5 and 6, in addition to the same configuration as the optical magnetic field detection apparatus according to claim 4, the optical magnetic field detection apparatus has the same configuration as each of claims 2 and 3. . For this reason, these claims also have the same effects as those of claims 2 and 3.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an optical magnetic field sensor and an optical magnetic field detection device according to the present invention will be described based on the drawings.
As shown in FIGS. 1 and 2, the optical magnetic field detection apparatus 10 according to the present embodiment transmits a sensor main body 12 that is an optical magnetic field sensor disposed in an electromagnetic field to be measured and a laser beam L. An optical system that can receive light is used.
[0021]
A pair of conductor patterns 16 formed on the glass epoxy printed circuit board 14 serving as a support portion of the sensor body 12 shown in FIG. , 18 are provided in a planar manner with a conductive material such as metal. The pair of conductor patterns 16 and 18 are arranged adjacent to each other on the printed circuit board 14 so that the ends of the pair of conductor patterns 16 and 18 are connected to each other and shared. Is provided with a gap 22 which is a gap.
[0022]
As shown in FIG. 1, a pair of parallel plate electrodes 20A and 20B are arranged at the ends of the pair of conductor patterns 16 and 18 forming the gap 22 so as to be parallel to each other, and are rectangular parallelepiped. The electro-optic element 24 formed in a shape is inserted and arranged at a location in the gap 22 so as to abut each of the pair of parallel plate electrodes 20A and 20B facing each other.
[0023]
As described above, the pair of conductor patterns 16 and 18 are arranged with the electro-optic element 24 interposed therebetween. Further, the electro-optic element 24 arranged in the gap 22 is formed of an electro-optic crystal. As the electro-optic crystal, for example, lithium niobate (LiNbO ₃₎ whose refractive index changes due to a change in applied voltage. ) Crystals are used.
[0024]
Therefore, the sensor main body 12 according to the present embodiment can be manufactured by the printed circuit board 14, the pair of conductor patterns 16, 18 and the electro-optical element 24. In the present embodiment, the magnetic field information is reliably obtained. The electro-optic element 24 is arranged so that the optical axis direction is in a predetermined direction so that extraction can be performed.
[0025]
Next, the entire optical system of the optical magnetic field detection apparatus 10 according to the present embodiment will be described with reference to FIG.
As shown in FIG. 2, the present embodiment has a laser light source 30 that generates a laser light L, and one end side of an optical fiber 32 is connected to the laser light source 30, and the other end of the optical fiber 32. A lens 32 </ b> A provided on the side and serving as a light emitting unit emits the laser light L sent from the laser light source 30. A polarizer 34 for polarizing the laser light L is disposed in the middle of the optical fiber 32.
[0026]
On the other hand, an optical fiber 40 is connected to a photodetector 42 that is a light detection member that converts a change in light intensity into a change in current amount, and a lens that is provided at an end of the optical fiber 40 and serves as a light receiving portion. 40A receives the laser beam L. For this reason, the laser light L received by the lens 40A passes through the optical fiber 40, and the photo detector 42 can detect the state of the laser light L. The photo detector 42 is connected to a spectrum analyzer 44 that can visually display a change in the amount of current converted by the photo detector 42.
[0027]
The lens 40A is disposed at a position where the laser light L emitted from the lens 32A can be received. Between the lens 32A and the lens 40A, the sensor body 12 is sequentially arranged from the lens 32A side. The electro-optic element 24, the wave plate 36, and the analyzer 38 that converts a change in polarization state into a change in light intensity are arranged side by side on a straight line. That is, this embodiment is a straight-ahead system in which the laser light L goes straight.
[0028]
As described above, when the laser light source 30 generates the laser light L, it passes through the optical fiber 32 and is emitted from the lens 32A. The laser light L passes in the above order and is received by the lens 40A of the optical fiber 40. It becomes like this. Then, the photodetector 42 detects the state of the laser light L that has entered the optical fiber 40 from the lens 40A.
[0029]
On the other hand, for example, when magnetic flux penetrates the pair of conductor patterns 16 and 18 shown in FIG. 1 which are conductive loops, current flows through the pair of conductor patterns 16 and 18, respectively. Along with this, a voltage is generated in the pair of parallel plate electrodes 20A and 20B provided at the connection portion of the pair of conductor patterns 16 and 18, and is arranged in the gap 22 between the pair of parallel plate electrodes 20A and 20B. This voltage is applied to the electro-optic element 24 thus formed to generate an electric field.
[0030]
The refractive index of the electro-optic element 24 changes due to the change in voltage. That is, the magnetic flux penetrating each of the pair of conductor patterns 16 and 18 becomes magnetic field information detected by the sensor body 12, and this magnetic field information is converted into a change in the refractive index of the electro-optic element 24.
[0031]
Furthermore, the optical magnetic field detection apparatus 10 according to the present embodiment temporarily changes the refractive index of the electro-optic element 24 as a change in the polarization state of the laser light L injected into the electro-optic element 24 from the structure shown in FIG. Can be caught. Then, by passing the analyzer 38, the change in the polarization state is converted into the change in the intensity of the laser beam L, and finally, the photo detector 42 converts it into the change in the amount of current. As a result, the spectrum analyzer 44 connected to the photo detector 42 displays the change in the current amount as a detection result, so that the magnetic field information around the sensor body 12 can be visually confirmed.
[0032]
From the above, the optical system of the optical magnetic field detection apparatus 10 according to the present embodiment includes the laser light source 30 and the photo detector 42, and an optical fiber disposed between the laser light source 30 and the photo detector 42. 32, a polarizer 34, a wave plate 36, an analyzer 38, an optical fiber 40, and the like.
[0033]
Next, the operation of the optical magnetic field detection apparatus 10 according to the present embodiment will be described.
According to the optical magnetic field detection apparatus 10 according to the present embodiment, as shown in FIG. 1 and FIG. 2, in a plane on the printed circuit board 14, a part is shared, that is, one end is connected to each other. In this way, a pair of conductor patterns 16 and 18 are formed adjacent to each other, each formed in an annular shape having the same shape from each other by a conductive material. An electro-optic element 24 is inserted into the gap 22 formed at the connecting portion of the pair of conductor patterns 16 and 18 with the optical axis direction adjusted.
[0034]
Further, the laser light L from the laser light source 30 is an optical fiber 32, a polarizer 34, an electro-optic element 24, a wave plate 36, an analyzer 38, and light disposed between the laser light source 30 and the photo detector 42. The photodetector 42 finally detects the state of the laser light L that has passed through the fibers 40 and passed through them.
[0035]
That is, the magneto-optical field detection device 10 according to the present exemplary embodiment uses a magneto-optical sensor in which the electro-optic element 24 is inserted in the gap 22 formed in the connection portion between the pair of conductor patterns 16 and 18 as the sensor body 12. It is said. Then, the sensor main body 12 is arranged at the measurement target portion, and the laser light L is allowed to pass through the electro-optical element 24, whereby the magnetic field information detected and acquired by the pair of conductor patterns 16 and 18 forming a double loop. Can be converted into an optical signal using the electro-optic effect of the electro-optic element 24 as described above, and this magnetic field information can finally be made visible by the spectrum analyzer 44.
[0036]
At this time, since the pair of conductor patterns 16 and 18 are respectively formed in a ring shape in a plane, and the pair of conductor patterns 16 and 18 are two-dimensionally formed in one plane, the direction of the magnetic flux However, the magnetic field information can be easily and more accurately acquired by simply arranging the plane perpendicular to the plane.
[0037]
Further, in the present embodiment, the polarizer 34, the wave plate 36, and the analyzer 38 disposed between the laser light source 30 and the photo detector 42 adjust the state of the laser light L, and are optimally adjusted. The state of the laser light L can be detected by the photo detector 42. Accordingly, the sensor body 12 according to the present embodiment transmits magnetic field information to the photo detector 42 which is a measuring machine by using an optical signal using the laser light L without using a metal transmission line such as a coaxial cable. In addition, since the metal portion is only the pair of conductor patterns 16, 18, the electromagnetic field around the measurement target portion to be measured is less likely to be disturbed.
[0038]
In particular, in the high frequency band such as the GHz band, since the laser light L is used, there is no possibility that the electric signal is affected by noise caused by the surrounding electric field in the middle of traveling through the transmission path, and detection is performed. The accuracy will not decrease. Similarly, since the laser beam L is used, there is no need for balanced / unbalanced conversion, and there is no decrease in detection accuracy due to imperfect balance / unbalanced conversion.
[0039]
As a result of the above, according to the optical magnetic field detection device 10 using the sensor body 12 according to the present embodiment, it is possible to measure a magnetic field with high accuracy from a low frequency band to a high frequency band, and the accuracy remains high. As the magnetic field information can be transmitted, the magnetic field information can be obtained with high accuracy even in the high frequency band.
[0040]
Next, the reason why magnetic field information can be acquired by the optical magnetic field detection apparatus 10 using the sensor body 12 according to the present embodiment will be described below.
For example, when there is a substrate provided with a wiring pattern (not shown) and a current I flows in this wiring pattern in the direction shown in FIGS. 3 and 4, a magnetic flux M is generated by Faraday's law of electromagnetic induction.
[0041]
As shown in FIG. 3, if the sensor body 12 according to the present embodiment is disposed in the vicinity of the wiring pattern, the magnetic flux M is generated in the inner conductor pattern 16 of the pair of conductor patterns 16 and 18. The magnetic flux M penetrates the conductor pattern 18 on the near side from the bottom to the top. That is, the magnetic flux M passes through the pair of conductor patterns 16 and 18 in opposite directions.
[0042]
As a result, if the magnetic flux M passes through the pair of conductor patterns 16 and 18 in the direction shown in FIG. 3, currents are generated in the pair of conductor patterns 16 and 18, respectively. Since a voltage is applied to the electro-optic element 24, the change in voltage is converted into a change in the refractive index of the electro-optic element 24.
[0043]
On the other hand, a large number of wiring patterns are generally formed on the substrate. However, when a current I flows through the wiring pattern far from the sensor body 12 as shown in FIG. The magnetic flux M penetrates from the top to the bottom in the same direction. Accordingly, the currents generated in the pair of conductor patterns 16 and 18 are canceled out, and no voltage is applied to the electro-optical element 24 disposed in the gap 22. As a result, the refractive index of the electro-optical element 24 does not change.
[0044]
As described above, according to the sensor main body 12 according to the present embodiment, the strength of the local magnetic flux M is converted into a change in the refractive index of the electro-optic element 24 without being disturbed by the magnetic flux M from the distant wiring pattern. This makes it possible to measure with high accuracy. The intensity of the magnetic flux M becomes magnetic field information detected by the sensor main body 12, and this magnetic field information can be transmitted to the photo detector 42 which is a measuring machine by an optical signal of the laser light L. Magnetic field information can be acquired with high accuracy.
[0045]
Further, in the above embodiment, the pair of conductor patterns 16 and 18 are rectangular, but the pair of conductor patterns 16 and 18 may be formed in other shapes such as a square and a circle. The conductor patterns 16 and 18 are not limited to thin metallic conductive materials as in the present embodiment, but may be members such as wires.
On the other hand, in the above embodiment, lithium niobate (LiNbO ₃ ) is employed as the electro-optic crystal, but other electro-optic crystals such as lithium tantalate (LiTaO ₃ ) may be employed.
[0046]
【The invention's effect】
According to the present invention, it is possible to provide an optical magnetic field sensor and an optical magnetic field detection apparatus that can acquire magnetic field information with high accuracy from a low frequency band to a high frequency band.
[Brief description of the drawings]
1A and 1B are views of a sensor main body according to an embodiment of the present invention, in which FIG. 1A is a plan view and FIG. 1B is a side view.
FIG. 2 is an overall view showing an optical magnetic field detection apparatus according to an embodiment of the present invention.
FIG. 3 is an explanatory diagram for explaining a state in which a magnetic flux passes through a pair of conductor patterns of a sensor main body according to an embodiment of the present invention, and is a diagram in a case where a current flows close to the sensor main body. is there.
FIG. 4 is an explanatory diagram for explaining a state in which a magnetic flux passes through a pair of conductor patterns of a sensor main body according to an embodiment of the present invention, and is a diagram when current flows away from the sensor main body. .
FIG. 5 is a perspective view of a main part of a conventional example.
[Explanation of symbols]
10 Optical Magnetic Field Detection Device 12 Sensor Body (Optical Magnetic Field Sensor)
16 Conductor pattern 18 Conductor pattern 22 Gap 24 Electro-optic element (electro-optic crystal)
30 Laser light source
42 Photo detector (light detection member)

Claims (6)

A pair of conductor patterns each formed in an annular shape by a conductive material and arranged adjacent to each other in a shared manner and a gap is formed in the connecting portion;
An electro-optic crystal inserted into a gap formed in a connection portion of the pair of conductor patterns;
An optical magnetic field sensor characterized by comprising: 2. The magneto-optical sensor according to claim 1, wherein the electro-optic crystal is formed of lithium niobate or lithium tantalate. 3. The magneto-optical sensor according to claim 1, wherein the pair of conductor patterns are formed in an annular shape having the same shape in a plane. A light source that generates light;
A pair of conductor patterns each formed in an annular shape by a conductive material and arranged adjacent to each other in a shared manner and a gap is formed in the connecting portion;
An electro-optic crystal that is inserted into a gap formed in a connection portion of the pair of conductor patterns and through which light from a light source can pass;
A light detection member for detecting the state of light passing through the electro-optic crystal;
An optical magnetic field detection device comprising: 5. The optical magnetic field detection apparatus according to claim 4, wherein the electro-optic crystal is formed of lithium niobate or lithium tantalate. 6. The optical magnetic field detection apparatus according to claim 4, wherein the pair of conductor patterns are formed in an annular shape having the same shape in a plane.

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