JPH056539Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical electric field/magnetic field detector that can simultaneously detect an electric field and a magnetic field.

[Prior art]

Optical electric field detectors detect the strength of an electric field by using the Pockels effect, a phenomenon in which the refractive index of the electric field detection element changes depending on the electric field strength, and uses a crystal as the electric field detection element placed in the electric field. is used in some cases.

Optical magnetic field detectors detect the strength of a magnetic field by using the Faraday effect, a phenomenon in which the plane of polarization of light rotates depending on the strength of the magnetic field. is used in some cases.

[Problem that the invention attempts to solve]

In areas with high voltages and large currents, such as power cables, it may be necessary to detect both electric and magnetic fields.In this case, conventionally, separate detectors were used to detect both separately. Ta. Therefore, there was a problem in that the detection work had to be performed twice, and the detection work took a long time. Another problem was that two detectors had to be prepared.

The present invention has been made in view of the above circumstances, and a polarizer is used to polarize light in two directions, one of which is circularly polarized and incident on an electric field detection element, and the other is incident on a magnetic field detection element, and the light from the electric field detection element and the magnetic field detection element is detected.
It can detect electric and magnetic fields simultaneously in one detection operation.
An object of the present invention is to provide an optical electric/magnetic field detector that can significantly reduce the operation time required to detect an electric field and a magnetic field.

[Means for solving problems]

The optical electric field/magnetic field detector according to the present invention is an optical electric field/magnetic field detector that optically detects an electric field and a magnetic field at the same time, and includes a polarizer that linearly polarizes light in two directions, and a polarizer that linearly polarizes light in two directions. a circularly polarizing means for circularly polarizing a linearly polarized light wave in one direction from the circularly polarizing means; an electric field detecting element into which the circularly polarized light wave from the circularly polarizing means is incident; and an electric field detecting element that receives light from the electric field detecting element and detecting the intensity of the light. , a magnetic field detecting element that receives the linearly polarized wave from the polarizer in the other direction, and a light receiving part that receives the light from the magnetic field detecting element and detects the intensity of the light. It is characterized by

[Effect]

Of the linearly polarized waves in two directions obtained by linearly polarizing the polarizer, one of the linearly polarized waves is circularly polarized and incident on the electric field detection element, and the other linearly polarized wave is incident on the magnetic field detection element as it is. Then, the light from the electric field detection element and the magnetic field detection element is detected separately. At the same time, electric and magnetic fields are detected.

〔Example〕

Hereinafter, the present invention will be explained based on drawings showing embodiments thereof. Figure 1 is a schematic plan view of the electric field/magnetic field detector according to the present invention (hereinafter referred to as the detector of the present invention);
The figure is a schematic diagram showing the polarization state, and 1 in the figure indicates a light emitting part. Light from the light emitting unit 1 (having vibration components in random directions) [see Figure 2a] passes through the light emitting optical fiber 2 and the lens system 3, and enters the polarizer 4 having a prism surface 4a. be done. The polarizer 4 has the function of linearly polarizing incident light in two perpendicular directions, and the light incident on the polarizer 4 is linearly polarized in two directions (see FIG. 2b).

Of the light linearly polarized in two directions, the first linearly polarized wave continues straight, enters the λ/4 plate 5, which is a circular polarizing means, and is circularly polarized while being transmitted through it [Fig. c], the light is incident on the crystal 6 which is an electric field detection element. On the other hand, the second linearly polarized light wave whose course has been deflected by 90 degrees is reflected by the prism surface 4a of the polarizer 4 and proceeds in the same direction as the first linearly polarized light wave,
The light is incident on lead glass 11, which is a magnetic field detection element.

On the output side of the crystal 6 and lead glass 11, there is an analyzer 7.
are provided with their one end surfaces in contact with each other. Note that the analyzer 7 is positioned such that its polarization plane is perpendicular to that of the analyzer 4.

The crystal 6 is a Z-cut type crystal having both ends cut perpendicularly to the Z-axis direction (vertical direction in FIG. 1), and has a rectangular parallelepiped shape long in the Z-axis direction.
When the circularly polarized light wave emitted from the λ/4 plate 5 receives an electric field in the X-axis direction (horizontal direction in Fig. 1) while passing through the crystal 6 in the Z-axis direction, it becomes an elliptically polarized light wave (Fig. 2 d). ], it rotates in that state and advances toward the output side, and enters the analyzer 7. Note that the crystal 6
The length in the Z-axis direction of is determined so that the twist angle of the vibration plane of the polarized light wave varies depending on the length, but in this embodiment, the component in the direction of the shortest axis of the elliptically polarized light wave is extracted. That is, the twist angle of the vibration plane of the polarized light wave between the incident end face and the outgoing end face of the crystal 6 of the elliptical polarized light wave is set to be an integral multiple of 90 degrees. Then, the elliptically polarized light wave that entered the analyzer 7 from the crystal 6 is linearly polarized by the analyzer 7, and becomes a polarized light wave in the direction of the shortest axis [see Figure 2 e].
only is emitted.

Like the crystal 6, the lead glass 11 has a rectangular parallelepiped shape that is long in the vertical direction in FIG. Then, it advances toward the emission side. Since the polarizer 4 and the analyzer 7 are positioned perpendicularly to each other, the intensity of the light emitted from the analyzer 7 increases as the plane of polarization rotates.

On the other end surface of the analyzer 7, lens systems 8a and 8b are bonded to the respective light emitting portions, and each linearly polarized light wave emitted from the analyzer 7 passes through the lens systems 8a and 8b.
The light-receiving optical fiber 9a connected to this through
9b and is captured by light receiving sections 10a and 10b.

The light receiving unit 10a is equipped with a photoelectric conversion element that extracts light as an electrical signal, a circuit that measures the amplitude of the light, and an arithmetic circuit that stores a correlation function that shows the relationship between the intensity level of the incident light and the strength of the electric field, and determines the strength of the electric field based on the intensity of the incident light, i.e., based on the amplitude of the linearly polarized wave.

The light receiving unit 10b includes a photoelectric conversion element that extracts light as an electrical signal, a circuit that measures the amplitude of light, and an arithmetic circuit that stores a correlation function that indicates the relationship between the intensity level of incident light and the intensity of the magnetic field. , the strength of the magnetic field is determined based on the intensity of the incident light, that is, the amplitude of the linearly polarized light wave.

The proposed detector is configured in this way, and λ/
4 While the circularly polarized light wave emitted from the plate 5 passes through the crystal 6, depending on the strength of the electric field applied to the crystal 6, the direction in which the electric field is detected in the crystal 6 is set as a large diameter, and the direction perpendicular to that direction is set as a small diameter. It becomes an elliptically polarized light wave. It is known that the degree of flatness of this elliptically polarized light wave increases as the electric field strength increases, and decreases as the electric field strength decreases, and that there is a correlation with the electric field strength. Then, the light intensity of the shortest diameter component of the elliptically polarized light wave is detected by the light receiving section 10a, and the electric field intensity is detected based on the detected value and the correlation function.

On the other hand, while the linearly polarized light wave emitted from the polarizer 4 passes through the lead glass 11, its polarization plane rotates depending on the strength of the magnetic field applied to the lead glass 11, and the polarization plane rotates depending on the rotation angle of the polarization plane. As a result, the intensity of light emitted from the analyzer 7 changes. It is known that the rotation angle of the polarization plane increases as the magnetic field strength increases, and decreases as the magnetic field strength decreases, and that there is a correlation with the magnetic field strength. Then, the intensity of light from the analyzer 7 is detected by the light receiving section 10b, and the magnetic field intensity is detected based on the detected value and the correlation function.

FIG. 3 is a plan view showing another embodiment of the present invention, and FIG. 4 is a schematic internal view in elevation showing the vicinity of the output side of the crystal 6 (lead glass 11) shown in FIG. In this embodiment, the electric field strength of the light emitted from the crystal 6 (lead glass 11) is reversed by the prism 12 provided between the crystal 6 (lead glass 11) and the analyzer 7. It has a structure that detects (magnetic field strength). With this structure, the detector can be made shorter than in the previous embodiment, and detection can be performed from one direction.

In addition, in this example, as the electric field detection element, crystal
Although the case where lead glass is used as the magnetic field detection element has been described, the present invention is not limited to this, and it goes without saying that any optical material may be used as long as it has the Pockels effect and the Faraday effect.

〔effect〕

As described in detail above, the detector of the present invention can simultaneously detect an electric field and a magnetic field in one detection operation, thereby reducing the time required for the detection operation. Furthermore, since voltage and current can be detected simultaneously, power can also be detected simultaneously.

Furthermore, since a unidirectional linearly polarized light wave from a polarizer, which was not used in the past, is used, there is no need to add a new light source (light emitting section).

Furthermore, the proposed detector can simultaneously detect electric and magnetic fields by adding only one set of a magnetic field detection element (or electric field detection element), a light-receiving optical fiber, and a light-receiving section to a conventional electric field detector (or magnetic field detector). Therefore, the present invention has excellent effects such as the overall size of the detector.

[Brief explanation of drawings]

Fig. 1 is a schematic plan view of the detector of the present invention, Fig. 2 is a schematic diagram showing the polarization form, Fig. 3 is a schematic plan view of another embodiment, and Fig. 4 is a partial elevational structural view of Fig. 3. be. 1... Light emitting section, 2... Optical fiber for light emission, 4...
...Polarizer, 5...λ/4 wavelength plate, 6...Crystal, 7
...Polarizer, 9a, 9b... Optical fiber for light reception,
10a, 10b... Light receiving section, 11... Lead glass.

Claims (1)

[Claims for Utility Model Registration] An optical electric field/magnetic field detector that optically detects an electric field and a magnetic field at the same time, comprising a polarizer that linearly polarizes light in two directions, and a polarizer that linearly polarizes light in one direction from the polarizer. a circularly polarizing means for circularly polarizing a linearly polarized light wave; an electric field detecting element for receiving the circularly polarized light wave from the circularly polarizing means; and a light receiving section for receiving light from the electric field detecting element and detecting the intensity of the light. , an optical system comprising: a magnetic field detection element that receives a linearly polarized wave in the other direction from the polarizer; and a light receiving section that receives light from the magnetic field detection element and detects the intensity of the light. Electric field/magnetic field detector.