JPH021268B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an alternating current electric field measuring device that measures an electric field using an optical element having an electro-optical effect.

FIG. 1 shows a principle diagram of measuring an electric field using a Pockels element as an optical element having an electro-optic effect. In the figure, 1 is a light source, 2 is a polarizer, 3 is a single Pockels element, 4 is an analyzer,
5 is the light receiver, 6 is the direction of the electric field, 7 is the light, 8a, 8
b indicates a high voltage electrode and a ground electrode that generate an electric field, respectively. The field 9 to be measured between the electrodes 8a and 8b is filled with a medium (including a vacuum).

In the above configuration, the light 7 emitted from the light source 1 is
The light passes through a polarizer 2, a Pockels element 3, and an analyzer 4 and enters a light receiver 5.

Since the Pockels element 3 has the property of changing the rotation angle of the light 7 passing therethrough in proportion to the strength of the electric field 6, it allows the light to pass from the outside of the housing into the field 9 to be measured. The electric field between the electrodes 8a and 8b can be measured without contacting the Pockels element 3 and in an electrically insulated state. However, if the electric field in the field to be measured is an alternating electric field, and the permittivity of the field to be measured is different from the permittivity of the Pockels element, the electric field in the field to be measured will be distorted by the insertion of the Pockels element, making it difficult to accurately The drawback was that it was not possible to measure electric fields.

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional devices, and includes providing a dielectric material in the field to be measured that brings the dielectric constant of the combination with the optical element close to the permittivity of the medium in the field to be measured. The present invention aims to provide an alternating current electric field measuring device that measures an electric field by reducing distortion of the electric field in a field to be measured.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In FIGS. 2 and 3, reference numeral 12 denotes a composite optical element, which is provided within the alternating current electric field of the field 9 to be measured. This composite optical element 12 has a structure in which a Pockels element is used as the optical element 10 in the center, and it is sandwiched from both sides in the direction perpendicular to the electric field by dielectric constants 10 and 11, which have different dielectric constants from the optical element 10 made of the Pockels element. It's summery. Here, the dielectric constant of the Pockels element 10 is εn (unit is omitted; the same applies hereinafter), the thickness is d ₁ ,
The cross-sectional area in the electric field direction is S, the dielectric constant of the dielectric 11 is εt, the thickness is d ₂ , the cross-sectional area in the electric field direction is S (in this example, it is the same as the Pockels element), and the field to be measured 9 is When the dielectric constant of the medium is εs, the capacitance Cn of the Pockels element 10 is Cn=εn・S/d ₁ , and the capacitance Ct of the dielectric 11 on both sides is Ct=εt・
It becomes S/2d ₂ . Therefore, Pockels element 1
The capacitance Cp of the composite optical element 12 in which the dielectric material 11 is integrally laminated on both the upper and lower sides of 0 is Cp=εn・εtS/
(εt・d ₁ +2εn・d ₂ ).

On the other hand, the capacitance C of the field to be measured 9 having the same volume as this composite optical element 12 is C=εsS/(d ₁ +
2d ₂ ). In order to prevent the composite optical element 12 from affecting the electric field of the field to be measured 9, the above-mentioned
Since it is sufficient to make Cp and C equal, εs(εtd ₁ +
2εnd ₂ )=εn·εt(d ₁ +2d ₂ ) must be established. Therefore, the thickness d ₂ of the dielectric 11 is
It is sufficient if d ₂ =εt(εs−εn)d ₁ /2εn(εt−εs).

The value of d ₂ is a value that makes Cp and C equal to each other, but if the value of Cp approaches the value of C even slightly, the distortion of the electric field is improved.

In addition, in the above embodiment, a composite optical element in which a Pockels element and a dielectric were laminated was shown, but the fourth embodiment
By embedding the Pockels element 10 in the dielectric 11 as in another embodiment of the present invention shown in the figure, it is possible to prevent distortion of the electric field at the side edges when stacked, making it more accurate. This makes it possible to measure electric fields.

Furthermore, even if the optical element 10 and the dielectric 11 are separate bodies and a medium is filled in between them, as in another embodiment shown in FIG. Can be reduced.

As described above, according to the present invention, in the alternating current electric field measuring device, a dielectric material is provided in the field to be measured that brings the dielectric constant of the combination with the optical element close to the permittivity of the medium in the field to be measured. This has the effect of reducing the distortion of the electric field in the field to be measured due to the element, thereby enabling more accurate measurement of the alternating current electric field.

[Brief explanation of drawings]

FIG. 1 is a schematic perspective view showing a conventional example of electric field measurement;
Fig. 2 is a principle diagram showing one embodiment of this invention;
The figures are a perspective view of an optical element used in FIG. 2, FIG. 4 is a perspective view of an optical element used in another embodiment of the invention, and FIG. 5 is a perspective view showing another embodiment of the invention. It is a diagram. In the figure, 9 is a field to be measured, 10 is an optical element,
11 indicates a dielectric material. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Scope of Claims] 1. In an alternating current electric field measuring device that measures an electric field by an optical element having an electro-optic effect provided in a field medium to be measured (including a vacuum), the dielectric constant of the combination with the optical element is An alternating current electric field measuring device, characterized in that a dielectric material that brings the dielectric constant close to that of the medium is provided in the field to be measured. 2. The alternating current electric field measuring device according to claim 1, wherein the dielectric body is integrally provided so as to sandwich the optical element from both sides in a direction perpendicular to the electric field. 3. The alternating current electric field measuring device according to claim 1, wherein the optical element is embedded within the dielectric material.