Optical-voltage sensor

a technology of optical voltage sensor and measurement sensitivity, which is applied in the field can solve the problems of difficult maintenance of fabrication accuracy, reduced insulation reliability, and complex structure of optical voltage sensor, and achieve the effects of increasing the degree of modulation, and increasing the measurement sensitivity of optical voltage sensor

Inactive Publication Date: 2002-09-12
SONE ISAMU +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

[0011] According to the structure described above, because the voltage to be measured is applied to the two electro-optical elements arranged adjacently to each other along the transmitting direction of the light at a time with a polarity opposite to each other, the Pockels effects are produced in the electro-optical elements with an inverse polarity and accordingly the degree of modulation can be increased even if the angle of optical rotation is increased. Thereby, the measurement sensitivity of the optical-voltage sensor can be increased.
[0012] As the method of producing the Pockels effects with an inverse polarity, in addition to the method of applying the voltage to be measured to each of the electro-optical elements with a polarity opposite to each other, as described above, there is another method that a crystal surface of one of the electro-optical elements is arranged inclining by 90 degrees with respect to that of the other of the electro-optical elements, and the voltage to be measured is applied to the both electro-optical elements with an equal polarity. That is, the present invention is characterized by an optical-voltage sensor having the structure similar to the optical-voltage sensor described above, wherein two of the electro-optical elements are arranged adjacently to each other along a transmitting direction of the light, and the two electro-optical elements are arranged so that an angle difference between crystal orientations of the electro-optical elements becomes 90 degrees in a plane perpendicular to the transmitting direction of the light, and a voltage to be measured is applied to each of the two electro-optical elements at a time with an equal polarity. In such a structure, the Pockels effects are also produced in the electro-optical elements adjacent to each other with an inverse polarity. Therefore, the measurement sensitivity of the optical-voltage sensor can be increased.
[0014] According to the structure described above, because the voltage to be measured is applied to the electro-optical elements adjacently to each other among the even number of electro-optical elements arranged continuously along a transmitting direction of the light at a time with a polarity opposite to each other, the Pockels effects are produced in the electro-optical elements with an inverse polarity and accordingly the degree of modulation can be increased even if the angle of optical rotation is increased. Thereby, the measurement sensitivity of the optical-voltage sensor can be increased.
[0015] Further, the present invention is characterized by an optical-voltage sensor having the structure similar to the optical-voltage sensor described above, wherein an even number of the electro-optical elements are arranged continuously along a transmitting direction of the light, and the even number of electro-optical elements are arranged so that crystal orientations of the even number of electro-optical elements are rotated by 90 degrees in a plane perpendicular to the transmitting direction of the light, and a voltage to be measured is applied to each of the even number of electro-optical elements at a time with an equal polarity. In such a structure, the Pockels effects are also produced in the electro-optical elements adjacent to each other with an inverse polarity. Therefore, the measurement sensitivity of the optical-voltage sensor can be increased.
[0016] Furthermore, the present invention is characterized by that the electro-optical element is formed so that a thickness of the electro-optical element in the transmitting direction of the light corresponds to an angle of natural optical rotatory power larger than 45 degrees. The construction as described above is effective to increase the degree of modulation.

Problems solved by technology

Therefore, there is a problem in that the reliability of insulation is reduced when the electric field is high.
On the other hand, the second prior arts have a problem in that the structure of the optical-voltage sensor becomes complex because the electro-optical crystals are laminated with inclining the crystal orientations.
Further, the method of using the electro-optical crystals cut with shifting the crystal orientation has a problem that the fabrication accuracy is difficult to maintain and the quality control becomes complex.
Furthermore, both of the proposed methods have a problem in that electric insulator is necessary to be placed between the laminated electro-optical elements and accordingly the structure becomes complex.

Method used

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embodiment 1

[0031] (Embodiment 1)

[0032] A first embodiment of the present invention will be described below, referring to FIG. 1. The optical-voltage sensor of the present embodiment comprises a light source 1, a polarizer 2, a 1 / 4 wavelength plate 3, an analyzer 5, and an O / E converting part 6. Two electro-optical elements 4a, 4b are arranged adjacent to each other along a transmitting direction of light between the 1 / 4 wavelength plate 3 and the analyzer 5. Transparent electrodes 7 are attached on both surfaces of each of the electro-optical elements 4a, 4b, and voltages having a magnitude equal to and a polarity opposite to each other are applied at a time to the electro-optical element 4a in the polarizer 3 side and the electro-optical element 4b in the analyzer 5 side from a power supply 8a and a power supply 8b, respectively. The optical-voltage sensor of the present embodiment measures the voltage of the power supplies 8a, 8b.

[0033] In the case of one element without the natural optical ...

embodiment 2

[0037] (Embodiment 2)

[0038] A second embodiment of the present invention will be described below, referring to FIG. 4. In the present embodiment, two electro-optical elements 4a, 4b are arranged adjacent to each other along a transmitting direction of light. Further, the electro-optical elements 4a, 4b are arranged so that the crystal orientations are rotated by 90.degree. (with an angle difference of 90.degree. in a plane perpendicular to the transmitting direction of the light. A voltage to be measured is applied to the electro-optical elements 4a, 4b at a time with an equal polarity from a power supply, which is not shown in the figure. Similarly to the case of FIG. 1, the present embodiment also comprises a light source 1, a polarizer 2, a 1 / 4 wavelength plate 3, an analyzer 5, and an O / E converting part 6, which are not shown in the figure, and the two electro-optical elements 4a, 4b are arranged between the 1 / 4 wavelength plate 3 and the analyzer 5.

[0039] In the structure desc...

embodiment 3

[0041] (Embodiment 3)

[0042] A third embodiment of the present invention will be described below, referring to FIG. 5. In the present embodiment, two electro-optical elements 4a, 4b compose one group, and the other group of electro-optical elements 4c, 4d having the same structure as the one group is added to the optical-voltage sensor. These electro-optical elements 4a, 4b, 4c and 4d are arranged between the 1 / 4 wavelength plate 3 and the analyzer 5. A voltage to be measured is applied to each of the electro-optical elements 4a, 4b, 4c and 4d at a time with polarities opposite to each other with respect to the adjacent electro-optical element from a power supply 8. For example, referring to FIG. 5, the positive voltage is applied to the transparent electrode in the left-hand side of the electro-optical element 4a and the negative voltage is applied to the transparent electrode in the right-hand side of the electro-optical element 4a, the negative voltage is applied to the transparen...

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Abstract

A measurement sensitivity of an electro-optical element higher is made highly sensitive, and an optical-voltage sensor having a simple structure capable of being formed by directly laminating the highly sensitive electro-optical elements is provided. The optical-voltage sensor comprises a light source 1, a polarizer 2, a 1 / 4 wavelength plate 3, an analyzer 5, and an O / E converting part. In the optical-voltage sensor in accordance with the present invention, two electro-optical elements 4a, 4b are arranged adjacent to each other along a transmitting direction of light between the 1 / 4 wavelength plate 3 and the analyzer 5. Transparent electrodes 7 are attached on both surfaces of each of the electro-optical elements 4a, 4b, and voltages having a magnitude equal to and a polarity opposite to each other are applied at a time to the electro-optical element 4a in the polarizer 3 side and the electro-optical element 4b in the analyzer 5 side from a power supply 8a and a power supply 8b, respectively.

Description

BACKGROUND OF THE INVENTION[0001] 1. Field of the Invention[0002] The present invention relates to an optical-voltage sensor for measuring a voltage with high accuracy and, more particularly to an optical-voltage sensor aimed at high sensitivity using an electro-optic crystal having a natural optical rotatory power.[0003] 2. Related Background Art[0004] There are some crystals in which a plane of polarization of linearly polarized light is rotated as the light travels when the light is transmitted through the crystals. This physical property is called as the natural optical rotatory power (hereinafter, referred to as optical rotatory power), and the angle of rotation of the linear polarization plane is called as the angle of optical rotation. An angle of optical rotation is proportional to a thickness of the crystal in a light transmission direction (hereinafter, referred to as a light path length). On the other hand, the optical-voltage sensor utilizes the electro-optical effect (P...

Claims

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Application Information

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Patent Type & AuthorityApplications(United States)
IPC IPC(8): G01R15/24G01R19/00
CPCG01R15/247
InventorSONE, ISAMUHIGAKI, MASARU
OwnerSONE ISAMU