JPH0237545B2 - HIKARINYORUDENKAI * JIKAISOKUTEIKI - Google Patents

Description

[Detailed description of the invention]

The present invention uses light to measure electric fields, magnetic fields, or currents in a non-contact manner.More specifically, the electric field is measured using the Pockels effect, and the magnetic field or the current that generates it is measured using the Faraday effect. It is something. Optical electric and magnetic field measuring instruments use optical fibers as transmission lines to provide a convenient and safe means of measuring even high-voltage, high-power transmission lines. When measuring electric and magnetic fields using conventional light, LiNbO ₃ , LiTaO ₃ , ADP, which have the Pockels effect,
A method has been used in which the electric field is measured using KDP and the magnetic field, that is, the current, is measured using lead glass or the like that has a Faraday effect. For this reason, it is necessary to use different materials and configure the sensor part, which forms the center of the measuring instrument, separately, and the electric field at the same point in space,
It was also not possible to measure the magnetic field at the same time. Furthermore, since there are two types of materials for the sensor part, there is also the disadvantage that the measuring device is expensive. The present invention eliminates the drawbacks of such conventional measuring methods and provides an electromagnetic field measuring instrument with further improved characteristics. The present invention will be explained below. In contrast to the conventionally used materials, which have only one of the Pockels effect and the Faraday effect, the present invention has the following advantages:
Bismuth silicon oxide (Bi ₁₂ SiO ₂₀ ) or bismuth germanium oxide (Bi ₁₂ GeO ₂₀ ) (hereinafter respectively BSO (abbreviated as BGO) is used to simultaneously measure electric and magnetic fields with a single sensor unit. The operating principle and configuration example are shown below. FIGS. 1 and 2 show the principles of electric field measurement using the Pockels effect and magnetic field measurement using the Faraday effect, respectively. In FIG. 1, incident light 1 (for example, He-
Ne laser light, light from a light emitting diode, etc.) is linearly polarized by an analyzer 2, circularly polarized by a λ/4 wavelength plate 3, and passed through a BSO or BGO single crystal 4 ((100) plate in this example). It passes through an analyzer 5 set at an angle of 45 degrees with the optical axis (x, y axes in the figure). When an electric field 6 of this arrangement is applied perpendicularly to a single crystal plate of thickness d with E=Eo sinwt (1), the light undergoes phase modulation due to the Pockels effect, and the intensity of light 7 exiting the analyzer becomes Io≒Ii/ It is well known that it is given by 2(1+πEd/Vπ) (2). Here Ii
is the incident light intensity, Vπ is the half-wave voltage,
For example, 3900volts with BSO for 633mm light,
BGO is 5600volts. Therefore, the light intensity expressed by equation (2) is detected by a photodetector (photodiode, etc.), and the AC component of the second term Ed
If we extract = Eod sinwt, we can obtain an electric signal proportional to the electric field. Although the above is a vertical element in which the electric field and light travel directions are parallel, it goes without saying that the same measurement is possible with a horizontal element in which the electric field and light travel directions are perpendicular. In FIG. 2, incident light 8 is converted into linearly polarized light by a polarizer 9, and after passing through a material 10 having a Faraday effect (such as lead glass) having a length l, an analyzer 11 forming an azimuth angle of 45° with the polarizer is used. Pass. Now, when an external magnetic field 12H=Ho sinwt (3) is applied to the single crystal parallel to the direction of light propagation, the polarization direction of the light transmitted through the single crystal is rotated by θ=Vel Ho sinwt (4) due to the Faraday effect. do. Therefore, the intensity Po of the light 13 after leaving the analyzer is Po≒1/2Pi (1-2θ) = 1/2Pi (1-2Vel Ho sinwt) (5), and if the AC component is extracted from the photodetector, then magnetic field
An electrical signal proportional to Ho can be obtained.
Since BSO and BGO have such Faraday effects, current can be measured by installing them under power transmission lines. The present invention utilizes the above-mentioned two effects of BSO and BGO to construct an electric field measuring device. As shown in the configuration example below, in the present invention, by appropriately selecting each plane orientation of the crystal and the traveling direction of the light, the light for measuring the electric field can only detect the Pockels effect, and the light for measuring the magnetic field can only detect the Faraday effect. The light source is He.
-Ne laser light, light from a light emitting diode or semiconductor laser, etc. are used, and the light transmission path is space or an optical fiber, and the method for introducing light into the crystal is a normal lens or rod lens. In order to reduce optical loss, it is desirable to input the light into a parallel light beam. Some configuration examples of the present invention will be described below, but the present invention is not limited to these described examples. In addition, the symbols in each figure are as shown in Figure 1,
The same thing as FIG. 2 is shown. Configuration example 1 Figure 3 shows an electric field detected by light transmitted in the <100> direction (vertical type), which is not affected by the Pockels effect at all <010
The magnetic field is detected using light transmitted in the > or <001> direction. Here, each direction is representative, and <100>, <010>, and <001> are mutually compatible. This also applies to the following examples. Configuration Example 2 FIG. 4 shows a configuration in which a reflective film 14 is provided on the end face of the crystal in order to further increase the sensitivity of (Configuration Example 1), and the number of reflections is determined based on the required sensitivity. Of course, it is also possible to make only either the electric field or the magnetic field reflective. In addition to increasing sensitivity, making it reflective like this
It is also useful for canceling the angular deviation due to the optical rotation power of BSO and BGO. Configuration Example 3 In FIG. 5, the input light beam is one beam, which is divided by the polarizing prism 2 into a component parallel to the plane of the paper and a component perpendicular to the plane of the paper, and these are reflected by the prism mirror 15, and the electric field is
By measuring each magnetic field with the latter, for example, if the incident light is transmitted using an optical fiber, one set of coupling system such as an optical fiber and a rod lens is not required compared to configuration examples 1 and 2, and the cost is reduced to 3 fibers. It has the above advantages. Configuration Example 4 In FIG. 6, an electric field is applied in the <110> direction, and the electric field is detected by light traveling in the <110> direction perpendicular to this (horizontal type). At this time, the light used to measure the magnetic field is transmitted in the <001> direction, which is not affected by the Pockels effect at all. For simplicity, the polarized analyzer and λ/4 plate are not shown. In this method, as in (Configuration Example 2), it is possible for at least one light to travel back and forth in the crystal, and the same result is obtained. Configuration Example 5 FIG. 7 shows a configuration in which the incident light is one beam in (Configuration Example 4), and has the same effect as (Configuration Example 3). Configuration Example 6 In Fig. 8, (Configuration Examples 1 and 4) require 4 optical fibers and a coupling system, only 2 optical fibers and a coupling system are required, resulting in lower cost,
Useful for miniaturization. In other words, a light source with two wavelengths (for example, 830 mm light and 870 mm light from a light emitting diode) is guided through an optical fiber, and the light is separated by a demultiplexer 16, leaving an electric field at one wavelength.
The magnetic field is measured in terms of wavelength, passes through analyzers 5 and 11 set at optimal angles, is combined by a multiplexer 17, and returns to the light receiver guided by a single fiber.
After being demultiplexed again on the receiver side, each signal is turned into an electric signal by a photodetector. Next, a case shown in Configuration Example 2 shown in FIG. 4 will be described as one specific embodiment of the present invention. In Fig. 4, a BSO (100) plate is added with a polarizing polarizing prism, a λ/4 wavelength plate, and a reflective layer, and the light input and output parts are coupled using a multimode optical fiber and a rod lens. The wavelength of the light used was 870 nm light from a light emitting diode. When we placed it under an experimental power transmission line and measured the electric and magnetic fields, i.e., current, it became clear that the detected electric field value was not affected by the current value, and the measured current value was not affected by the applied voltage of the transmission line, that is, the electric field. Summer. The same is true when using BGO in other configuration examples,
The features of the present invention were similarly confirmed in other configuration examples. As described above, according to the optical electric field/magnetic field measuring device of the present invention, (1) it can be configured into a single sensor section, so the expensive sensor section can be reduced in price; It has the advantages of requiring only one alignment, being able to measure the electric and magnetic fields at the same point in space, and being easy to use as it only requires one sensor unit. (2) Furthermore, using BSO and BGO has the following advantages. First, as an electric field measuring device, LiNbO ₃ ,
It does not have natural birefringence like LiTaO ₃ , so stable measurements can be made without temperature compensation.
Since it is a stable material that does not have deliquescent properties like ADP and KDP, it has the advantage of not requiring special sealing. Furthermore, as a magnetic field measuring device, it has almost no temperature dependence like lead glass, and has a Verdet constant (Ve = 0.2 min/Oe・
cm, wavelength λ = 633 nm), it has high sensitivity, and because it is a single crystal material, it has the advantage of low light absorption loss.

[Brief explanation of drawings]

Figure 1 is a diagram showing the principle of electric field measurement, Figure 2 is a diagram showing the principle of magnetic field measurement, and Figures 3, 4, 5, 6, 7, and 8 are diagrams showing configuration examples of the measuring instrument of the present invention. be. In the figure, 1, 8...incident light, 2,9...polarizer, 3
...λ/4 wavelength plate, 4,10...BSO or
BGO single crystal, 5, 11... analyzer, 6... electric field,
7, 13... Emitted light, 12... Magnetic field, 14... Light reflection layer, 15... Prism mirror, 16... Demultiplexer, 17... Multiplexer, E... Electric field, H... Magnetic field.

Claims (1)

[Claims] 1. An optical material having both a Pockels effect and a Faraday effect is placed in a space where electric and magnetic fields perpendicular to each other exist in a direction in which the vertical Pockels effect of the optical material is maximum with respect to the direction of the electric field. Place it in
The light for measuring the electric field is made to travel in the same direction as the electric field and transmitted through the optical material, and the light for measuring the magnetic field is made to travel in the same direction as the magnetic field and transmitted through the optical material, or The optical material is placed in the direction where the lateral Pockels effect of the optical material is maximized with respect to the direction of the electric field, and the light for measuring the electric field is directed to the direction of the electric field.
Electric and magnetic fields are generated by light by traveling in the direction perpendicular to the magnetic field and transmitting through the optical material, and by transmitting light for measuring the magnetic field in the same direction as the magnetic field and transmitting through the optical material. An optical electric field/magnetic field measuring device that measures simultaneously. 2. The optical electric field and magnetic field measuring instrument according to claim 1, wherein the optical material is bismuth silicon oxide (Bi ₁₂ SiO ₂₀ ) or bismuth germanium oxide (Bi ₁₂ GeO ₂₀ ). 3 The <100> direction of Bi ₁₂ SiO ₂₀ or Bi ₁₂ GeO ₂₀ is parallel to the electric field direction, and the <010> direction or <
001> Arranged so that the direction is parallel to the magnetic field direction,
Electric and magnetic field measurement using light according to claim 1, characterized in that the light for measuring the electric field travels in the same direction as the direction of the electric field, and the light for measuring the magnetic field travels in the same direction as the direction of the magnetic field. vessel. 4 Arrange the Bi ₁₂ SiO ₂₀ or Bi ₁₂ GeO ₂₀ so that the <110> direction is parallel to the electric field direction and the <001> direction is parallel to the magnetic field direction, and the light for measuring the electric field is <T10> The light that travels in the direction and measures the magnetic field is <
001> The electric field/magnetic field measuring instrument using light according to claim 1, characterized in that the light travels in the direction. 5 The incident light is split into two mutually orthogonal polarization components by a polarizing beam splitter, while the electric field is
The optical electric field/magnetic field measuring instrument according to any one of claims 1 to 4, characterized in that it measures a magnetic field while remaining. 6 The incident light consists of two different wavelengths, which are separated by an optical demultiplexer and the electric field is created by one wavelength.
An optical electric field/magnetic field measuring instrument according to claims 1 to 4, characterized in that the magnetic field is measured using light of one of the remaining wavelengths.