JP2000235049A - Photovoltage/electric field sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a measurement error due to temperature characteristics of a wavelength plate in a photovoltage sensor with the use of an electro-optical crystal. SOLUTION: This photovoltage/electric field sensor includes a total internal reflection prism 27 for splitting an optical circuit into forward and backward paths 23a, 23b, and a λ/8 plate 26 (λ: wavelength) inserted in both the paths 23a and 23b, while an electro-optical crystal 22 is inserted as a vertical crystal of Bi12GeO20 or Bi12SiO20 into only one of the forward and backward paths 23a, 23b. Accordingly, an electro-optical effect can be provided by impressing a power supply 30 to the crystal 22 inserted in only one of the forward and backward paths 23a, 23b, while errors caused by the λ/8 plate 26 cancel each other out. Thus, the measuring accuracy can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical voltage / electric field sensor for measuring a voltage or an electric field using an electro-optic crystal such as a Pockels element.

[0002]

2. Description of the Related Art A voltage transformer is widely used for measuring a voltage of a power system. However, this voltage transformer has a problem that the larger the system voltage to be measured, the larger the size, and the cost and space increase. In particular, in a gas insulated switchgear using an inert gas called GIS, miniaturization and space saving are strongly required.
It is difficult to mount such a voltage transformer.

[0003] For this reason, an optical voltage sensor using an electro-optic crystal such as a Pockels element has been used. FIG. 7 is a front view showing a structure of a main part of a typical conventional optical voltage sensor 1 using such an electro-optic crystal. In this optical voltage sensor 1, light from a light source (not shown) such as a semiconductor laser
Through the collimator 3, is converted into parallel light, and is incident on the polarizer 4. Although the incident light from the collimator 3 to the polarizer 4 is parallel light, its polarization direction is random, and after being linearly polarized by the polarizer 4, is incident on the λ / 4 plate 5. The linearly polarized light from the polarizer 4 is incident at an angle of 45 ° with respect to the optical axis (c-axis) of the λ / 4 plate 5, whereby the light passing through the λ / 4 plate 5 Is circularly polarized light.

The circularly polarized light from the λ / 4 plate 5 is incident on a Pockels element 6 which is an electro-optic crystal, and the light emitted from the Pockels element 6 is extracted by the analyzer 7 with only a linearly polarized component in a predetermined direction. Then, the light is emitted from the collimator 8 to the optical fiber 9 and is incident on a light receiving element (not shown). In the Pockels device 6, transparent electrodes 11 and 12 are formed on a light incident surface and a light emitting surface, respectively.
A voltage of the power system is divided and supplied as a power source 13 between the transparent electrodes 11 and 12.

[0005]

In the optical voltage sensor 1 constructed as described above, the λ / 4 plate 5 is generally made of quartz, and like the Pockels element 6,
It has an electro-optic effect, and there is a problem that accuracy is deteriorated due to the influence of an electric field. Further, the λ / 4 plate 5 has a birefringent property, and has a problem that the temperature characteristics are poor compared to the Pockels element 6.

An object of the present invention is to provide an optical voltage / electric field sensor capable of suppressing a measurement error caused by a wave plate.

[0007]

According to the first aspect of the present invention, there is provided an optical voltage / electric field sensor comprising a polarizer, a wave plate, an electro-optic crystal,
And an analyzer to form an optical path, the electro-optic crystal performs phase modulation on passing light according to an applied voltage or an electric field, and measures a measured voltage or an electric field from the phase difference. In the electric field sensor, a total reflection member is interposed in the optical path, and the electro-optic crystal is made of Bi ₁₂ Ge.
As an O ₂₀ crystal or a Bi ₁₂ SiO ₂₀ crystal, only one of the optical paths to and from the total reflection member intervenes in the optical path, the wavelength plate is a １ ／ wavelength plate, and the light to and from the total reflection member is It is characterized by being arranged together on a route.

According to the above arrangement, the wavelength plate is a １ ／ wavelength plate, and light is reciprocated to this wavelength plate by using a total reflection member realized by a total reflection prism or a polarization analyzer. The error and the optical rotation due to the wave plate are canceled. Since light passes through the electro-optic crystal only in one way, even in the case of a vertical crystal in which a voltage / electric field needs to be applied in the optical axis direction, modulation corresponding to the applied voltage / electric field can be generated as usual. it can.

According to a second aspect of the present invention, there is provided an optical voltage / electric field sensor comprising a polarizer, a wave plate, an electro-optic crystal, and an analyzer to form an optical path. In the optical voltage / electric field sensor configured to measure a voltage or an electric field to be measured based on the phase difference, a total reflection member is interposed in the optical path, and the electro-optic crystal is , A Bi ₁₂ GeO ₂₀ crystal or a Bi ₁₂ SiO ₂₀ crystal, which is divided into two in the optical axis direction, and is interposed in each of the reciprocating optical paths to the total reflection member so that the crystal axes are different from each other by 90 °. The wave plate is 1
/ 8 wavelength plate, and are disposed together in a light path reciprocating to the total reflection member.

According to the above configuration, the wavelength plate is a ８ wavelength plate, and light is reciprocated to the wavelength plate by using a total reflection member realized by a total reflection prism or a polarization analyzer. The error and the optical rotation due to the wave plate are canceled. Although light passes back and forth through the electro-optic crystal, the electro-optic crystal is divided into two in the optical axis direction, that is, 1
/ 2 is interposed so that the crystal axes are different from each other by 90 °. Therefore, even in the case of a vertical crystal in which a voltage / electric field needs to be applied in the optical axis direction, the applied voltage is normally Modulation corresponding to an electric field can be generated. In addition, since the electro-optic crystal is arranged in both the light path to and from the total reflection member and the thickness thereof is reduced to １ ／, the size of the sensor can be reduced, and both the light path and the light path are free. The space is eliminated, the optical components can be assembled closely, and the assembling operation can be simplified and the accuracy can be improved.

Further, the optical voltage / electric field sensor according to the invention of claim 3 is characterized in that a collimator or a ball lens is integrally formed in the polarizer and the analyzer.

According to the above configuration, the collimator and the ball lens are embedded in the polarization analyzer, the polarizer, and the analyzer, so that there is no protrusion and the size can be further reduced. It is also possible to simplify the assembling work, such as reducing the number of optical axes and eliminating the need for optical axis alignment.

In the optical voltage / electric field sensor according to a fourth aspect of the present invention, the lengths of two sides orthogonal to each other on the light incidence surface and the light emission surface of the rectangular electro-optic crystal are W and W, respectively. H, the lengths of two sides orthogonal to each other on the light incident surface and the light exit surface of the total reflection member and the wavelength plate are 2 W and H, respectively. The polarizer and the analyzer When the lengths of two sides orthogonal to each other on the exit surface are W and H, respectively, and the length in the optical axis direction is W, or when the polarizer and the analyzer are integrally formed as a polarized analyzer, The lengths of two sides orthogonal to each other on the light entrance and exit surfaces are each 2
W, H, and the length in the optical axis direction are 2 W.

According to the above configuration, each optical component is mounted on a flat plate such as the bottom surface of the housing, and the polarizer and the analyzer are integrally combined, or the polarizer and the analyzer are also used. The end faces of the polarization analyzer, the wave plate, and the electro-optic crystal are brought into contact with a wall surface or the like of a housing perpendicular to the bottom surface, and the side surface of the total reflection member is also brought into contact with the wall surface or the like, so that light is emitted. Either the outgoing route or the return route of the route is W
/ 2, and the other one of the outward path and the return path of the optical path is further formed at the position of W from that position, so that the optical axis of the optical component can be easily adjusted.

Further, in the optical voltage sensor according to the invention of claim 5, the electro-optic crystal has a transparent electrode formed on an incident surface and an exit surface of the light, and a height of a lead wire extraction in the H direction. It is characterized by being formed higher by α.

According to the above configuration, when the sensor is an optical voltage sensor, a transparent electrode is formed on the light incident surface and the light emitting surface, so that the electro-optic crystal can be moved in the H direction with respect to the transparent electrode. It is formed to be higher by the height α of the lead wire.

Therefore, in the electro-optic crystal, since the conductive adhesive or solder for connecting the lead wire is not provided in the portion of the other optical component up to the height H, the electro-optic crystal is connected to the adjacent optical component. It is possible to assemble them in close contact with each other, and it is possible to simplify manufacturing such that it is not necessary to provide an antireflection film on the light incident surface and the light exit surface.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described.
The following is a description based on FIG. 1 and FIG.

FIG. 1 is an exploded perspective view showing a structure of a main part of an optical voltage sensor 21 according to an embodiment of the present invention, and FIG. 2 is a front view showing an assembled state of the main part. This optical voltage sensor 21 uses BGO (Bi ₁₂ Ge) as an electro-optical crystal.
O ₂₀ ) crystal 22 is used.
In addition to the crystal 22, a Bi ₁₂ SiO ₂₀ crystal may be used,
It is a vertical crystal to which a voltage or an electric field is to be applied in the direction of the optical axis 23, which will be described later.

Light from a light source (not shown) such as a semiconductor laser is applied to a collimator 24 via an optical fiber.
The light is collimated by the collimator 24 and is incident on the polarization detector 25. Light having a random polarization direction from the collimator 24 has a predetermined linear polarization component extracted by the polarization analyzer 25 and is incident on a λ / 8 plate 26 which is a wavelength plate.

The polarization direction of the λ / 8 plate 26 intersects with the polarization direction of the polarization detector 25 by 45 °. After being decomposed into axial (a-axis, c-axis) components and propagated,
The light is emitted with a phase difference of 1/8 of the wavelength between the two optical axis components between the surface 26a on the side and the surface 26b on the BGO crystal 22 side. The output light of the λ / 8 plate 26 is BGO
After passing through the crystal 22, it is incident on the total reflection prism 27.

In the total reflection prism 27, the traveling direction is 1
The light inverted by 80 ° is again incident on the polarization detector 25 via the λ / 8 plate 26, and only a predetermined linearly polarized light component is extracted, and is transmitted from the collimator 28 to the light receiving element via an optical fiber (not shown). Given. The collimator 28 disposed on the optical axis 23 in order to detect a linear polarization component perpendicular to the linear polarization component received by the collimator 28 in order to cope with a change in the characteristics of the λ / 8 plate 26 and the like. However, a collimator 29 may be provided so as to be orthogonal to the optical axis 23.

With this configuration, λ / 8
Since light passes through the plate 26 twice, the phase of λ / 4 is generated. Therefore, the measurement result is configured such that the linearly polarized outgoing light from the polarization detector 25 is incident on the BGO crystal 22 as circularly polarized light by a wave plate, as in the conventional optical voltage sensor 1 shown in FIG. Similarly, the collimators 28 and 29 are supplied with a BG
Corresponding to the voltage applied to the transparent electrodes 22a and 22b of the O crystal 22, linearly orthogonally polarized light components of light converted into elliptically polarized light by the BGO crystal 22 are incident.

The λ / 8 plate 26 is made of quartz or the like, and its thickness D can cause a phase difference of １ ／ wavelength between the a-axis component and the c-axis component of the incident light. Selected for thickness. The crystal length of the BGO crystal 22 is represented by L, and when the width of a plane perpendicular to the optical axis 23 of the BGO crystal 22 is W, the remaining optical components 25, 26, and 27 have 2W.
It is formed in the width of. Also, the remaining optical components 25, 26,
The height of 27 is formed in H. For example, W = H = 5
(Mm).

When the sensor 1 is an optical electric field sensor, the BGO crystal 22 is formed at the height H. In the case of an optical voltage sensor as in this embodiment, the light incident surface and the outgoing light The transparent electrodes 22a,
The lead wire 22b is formed higher than the lead wire 22b by α. The lead wire is electrically connected to the transparent electrodes 22a and 22b by a conductive adhesive or soldering. The width and depth of the polarization analyzer 25 are both 2 W
Is formed.

As shown in FIG. 2, a BGO crystal 22 is interposed on the outward path 23a side of the optical path, and each optical component 25,
26, 22, 27 are arranged close to each other. On the other hand, on the return path 23b side of the optical path where the BGO crystal 22 is not interposed, the surface of the total reflection prism 27 on the λ / 8 plate 26 side and the surface of the λ / 8 plate 26 on the total reflection prism 27 side are different. AR (Air Reflection) films 27r, 26r to suppress reflection at the interfaces.
Is formed by vapor deposition or the like.

The optical voltage sensor 21 configured as described above
In this case, both the outgoing path 23a and the return path 23b of the optical path have λ /
By interposing the eight plates 26, a phase difference of 1/4 wavelength can be generated in accordance with the transmitted light, as in the optical voltage sensor 1 of the prior art shown in FIG.
The factors of the measurement error generated in the eight plates 26 have opposite characteristics between the forward path 23a and the backward path 23b, and are canceled out. Thus, a measurement error in the wave plate can be suppressed.

Each of the optical parts 25, 26, 22, 27
Puts its bottom surface on a flat plate such as the bottom surface of the sensor housing, and analyzes the polarization detector 25, the λ / 8 plate 26, and the BGO crystal 22.
, The end faces 25d and 26d on the outward path 23a side and the side surface 27d on the outward path 23a side of the total reflection prism 27 are
Just by touching the wall surface perpendicular to the bottom surface of the housing,
From the end faces 25d, 26d, 22d and side faces 27d,
The outward path 23a is formed at the position of W / 2, and the return path 23b is formed at the position of W / 2 from the opposite end surfaces 25e, 26e and the side surface 27e. Thus, the optical axis can be easily aligned.

Further, when the sensor 1 is an optical voltage sensor, the BGO crystal 22 is connected to the transparent electrodes 22a, 22a.
Since the lead is formed higher by the height α of the lead wire with respect to b, the conductive adhesive and the solder are not provided in the portion up to the height H of the adjacent λ / 8 plate 26 and the total reflection prism 27. It is possible to assemble them in close contact with each other, and it is also possible to simplify the manufacturing such that it is not necessary to provide an anti-reflection film on the light entrance surface and the light exit surface.

The λ / 8 plate 26 is provided between the polarization detector 25 and the B
Not only between the GO crystal 22 but also between the BGO crystal 22 and the total reflection prism 27,
It goes without saying that the O crystal 22 may be provided in the return path 23b. In the present specification, the wave plate 26
Is referred to as a λ / 8 plate as described above, but if optical rotation occurs in the total reflection prism 27, the wavelength plate 26
Assuming that the phase difference at θ1 is θ1 and the phase difference at total reflection prism 27 is θ2, 2θ1 + θ2 波長 λ / 4, that is, the phase difference at wavelength plate 26 is 1 /
The value is set to の of the value obtained by subtracting the phase difference θ2 from the four wavelengths.

On the other hand, FIGS. 8 and 9 show the structures of the main parts of other conventional optical voltage sensors 51 and 61, respectively. The optical voltage sensor 51 of FIG. 8 is described in JP-A-10-54849 and JP-A-7-63791, and the optical voltage sensor 61 of FIG.
No. 54849. These optical voltage sensors 51 and 61 are composed of a polarization detector 52 and a λ / 8 plate 5.
3 and a total reflection mirror 54, and is similar in that light is reciprocated in the λ / 8 plate 53.

However, the light reciprocates in the electro-optic crystals 55 and 65 because of the total reflection mirror 54. Therefore, like the optical voltage sensor 51 shown in FIG. 8, the electro-optic crystal 55 is configured to apply a voltage or an electric field from a direction perpendicular to the optical axis 56 to ZnTe, G
A horizontal crystal such as aP, LiNbO ₃ , Bi ₃ GeO ₁₂ or the like can be used for the measurement, but as shown by the optical voltage sensor 61 in FIG.
In a vertical crystal similar to the present invention to which a voltage or an electric field is to be applied in the direction, the modulation due to the applied voltage or the electric field is canceled by the reciprocation of the light, and the measurement is impossible. In this regard, in the present invention, measurement is enabled by interposing the vertical crystal only in one of the outward path 23a and the return path 23b of the optical path. In general, vertical crystals are three times or more higher in sensitivity than horizontal crystals, and are advantageous in terms of cost and space.

Another embodiment of the present invention will be described below with reference to FIG.

FIG. 3 is a front view showing the structure of the main part of an optical voltage sensor 31 according to another embodiment of the present invention. In this optical voltage sensor 31, similar to the above-described optical voltage sensor 21, corresponding portions are denoted by the same reference numerals, and description thereof will be omitted. It should be noted that this optical voltage sensor 31
Then, the optical components 25 in the optical voltage sensor 21 described above,
26, 27 are separate parts 25A, 25B; 26A, 26B; 2 for the outward path 23a and the return path 23b of the optical path, respectively.
7A and 27B. Polarizer 2
Light from the ball lens 34 is incident on 5A, and light emitted from the analyzer 25B is incident on the ball lens 38.

Therefore, these optical components 25A, 2A
The widths of 5B; 26A, 26B; 27A, 27B are also common to the W. In particular, although the polarization detector 25 is a single component and is advantageous for reducing the number of components, the polarizer 25A and the analyzer 25B are thus advantageous. And the depth is changed from 2W to W, so that miniaturization is possible. Further, the total reflection member also uses two polarization analyzers 27A and 27B in combination instead of the total reflection prism 27,
Parts can be shared with the polarizer 25A and the analyzer 25B.

Regarding still another embodiment of the present invention,
The following is a description based on FIGS. 4 and 5.

FIG. 4 is an exploded perspective view showing the structure of the main part of an optical voltage sensor 41 according to still another embodiment of the present invention.
FIG. 5 is a front view showing an assembled state of the main part. In this optical voltage sensor 41, the above-described optical voltage sensor 21,
31 are denoted by the same reference numerals, and description thereof is omitted. It should be noted that in this optical voltage sensor 41, the BG in the optical voltage sensor 21 described above is used.
The O crystal 22 is divided into two in the direction of the optical axis 23, that is, is composed of BGO crystals 22A and 22B having a crystal length of L / 2, and these BGO crystals 22A and 22B are connected to the forward path 23a of the optical path and the return path. 23b, the crystal axis A on a plane perpendicular to the optical axis 23, that is, on a light incident surface and a light incident surface.
1 and B1 are arranged to be shifted from each other by 90 °.

The crystal axis A1 of the BGO crystal 22A is
The a-axis and c-axis of the λ / 8 wave plate 26A intersect at 45 ° with each other, and the crystal axis B1 of the BGO crystal 22B is shifted from the crystal axis A1 in any of the directions of 90 °, + or-. You may.

Transparent electrodes 22Aa, 22Ab; 2 are provided on the light incident surface and the light exit surface of the BGO crystals 22A, 22B.
2Ba and 22Bb are formed. Transparent electrode 22A
a, 22Ab; 22Ba, 22Bb share a power source 3
0 is connected.

Therefore, the above-described optical voltage sensors 21, 3
As in the case of 1, the wavelength plates are λ / 8 wavelength plates 26A and 26B, and the total reflection prism 27 is used.
In order to cancel the error and the optical rotation due to the wave plate by reciprocating the light to and from the BGO crystal 26B, the light passes through the BGO crystals 22A and 22B in a reciprocating manner.
Since the GO crystals 22A and 22B have a crystal length of L / 2 and their crystal axes A1 and B1 are shifted from each other by 90 °, the voltage and the electric field can be measured similarly to the optical voltage sensors 21 and 31 described above. .

Further, the length of the electro-optic crystal is reduced to half of that of the optical voltage sensor 21, so that the size of the sensor can be reduced. Furthermore, the round-trip optical path 23
Both a and 23b have no empty space, and optical components 25A and 25B; 26A and 26B; 22A and 22B;
7 can be assembled in close contact, the assembling operation can be simplified, the reliability against vibration and the like can be improved, and the interface with the air can be eliminated.
It is not necessary to form r and 26r.

Furthermore, when the crystal length of the electro-optic crystal is simply set to 、 and the crystal axes A1 and B1 are interposed in the forward path 23a and the return path 23b of the optical path in parallel with each other,
Transparent electrodes 22Aa, 22Ba and 22 adjacent to each other
Ab and 22Bb must be connected to terminals of opposite polarity of the power supply 30, respectively, and the withstand voltage is reduced. On the other hand, in the present optical voltage sensor 41, adjacent transparent electrodes 22Aa, 22Ba and 22Ab And 22Bb have the same potential as each other, and the withstand voltage can be improved.

Another embodiment of the present invention will be described below with reference to FIG.

FIG. 6 is a front view showing an assembled state of a main part of an optical voltage sensor 41a according to another embodiment of the present invention.
In the optical voltage sensor 41a, the collimators 24 and 28 in the optical voltage sensor 41 described above are embedded in the polarizer 25A and the analyzer 25B, respectively.

As described above, the polarization detector 25 and the polarizer 2
By embedding collimators 24 and 28 and ball lenses 34 and 38 in 5A and analyzer 25B,
Since there is no protrusion, the size can be further reduced, and the number of components can be reduced, and the assembling work can be simplified such that the optical axis alignment becomes unnecessary.

[0046]

The optical voltage / electric field sensor according to the first aspect of the present invention comprises a polarizer, a wave plate, an electro-optic crystal,
An optical path is formed with an analyzer, and the electro-optic crystal performs phase modulation of transmitted light according to an applied voltage or an electric field, and measures a voltage or an electric field to be measured from the phase difference. In the sensor, the wave plate is 1/8
In addition to the wave plate, a total reflection member is interposed in the optical path, and light is reciprocated to the wave plate by the total reflection member, thereby canceling an error caused by the wave plate.

Therefore, the measurement error due to the wave plate can be suppressed, and since the light passes through the electro-optic crystal only in one way, the electro-optic crystal has high sensitivity, but the voltage / electric field is reduced in the optical axis direction. Even if it is a vertical crystal that needs to be applied to an electro-optic crystal, the electro-optic crystal can modulate incident light according to the applied voltage and electric field with the usual high sensitivity.

The optical voltage / electric field sensor according to the second aspect of the present invention comprises a polarizer, a wave plate, an electro-optic crystal, and an analyzer to form an optical path as described above. Performs phase modulation on passing light in accordance with an applied voltage or an electric field, and measures a voltage or an electric field to be measured from the phase difference.
In addition to the / 8 wavelength plate, a total reflection member is interposed in the optical path, and light is reciprocated to the wavelength plate by the total reflection member, thereby canceling an error caused by the wavelength plate. Then, the electro-optic crystal is divided into two in the direction of the optical axis, and is interposed in each of the reciprocating optical paths to the total reflection member so that the crystal axes are different from each other by 90 °.

Therefore, the measurement error due to the wave plate can be suppressed, and the light passes through the electro-optic crystal in a reciprocating manner. Even in the case of a vertical crystal that needs to apply an electric field in the direction of the optical axis, the electro-optic crystal can modulate incident light in accordance with the applied voltage and electric field with the usual high sensitivity. In addition, since the electro-optic crystal is arranged in both the light path to and from the total reflection member and the thickness thereof is reduced to １ ／, the size of the sensor can be reduced, and both the light path and the light path are free. The space is eliminated, the optical components can be assembled closely, and the assembling operation can be simplified and the accuracy can be improved.

Further, in the optical voltage / electric field sensor according to the third aspect of the present invention, as described above, the collimator and the ball lens are integrally formed in the polarization detector, the polarizer, and the analyzer.

Therefore, there is no protrusion, so that the size can be further reduced, and the number of parts can be reduced, and the assembling work can be simplified such that the optical axis is not required.

According to a fourth aspect of the present invention, there is provided an optical voltage / electric field sensor as described above, wherein two sides orthogonal to each other on the light incident surface and the light exit surface of the rectangular electro-optic crystal. Where W and H are respectively W and H, the lengths of two mutually orthogonal sides of the light incident surface and the light exit surface of the total reflection member and the wavelength plate are 2W and H, respectively.
Wherein the polarizer and the analyzer have two sides W and W, respectively, which are orthogonal to each other on the light entrance and exit surfaces, respectively.
H, the length in the optical axis direction is W, or when the polarizer and the analyzer are integrally formed as a polarization analyzer, the lengths of two sides orthogonal to each other at the light incidence and emission surfaces. Are 2W and H, respectively, and the length in the optical axis direction is 2W.

Therefore, each optical component is placed on a flat plate such as the bottom surface of the housing, and a polarizer and an analyzer are integrally combined, or a polarizer and an analyzer which are both used as an analyzer. The wavelength plate and the end surface of the electro-optic crystal are brought into contact with the wall surface of the casing perpendicular to the bottom surface, and the side surface of the total reflection member is also brought into contact with the wall surface, etc. One of the return paths is formed at a position of W / 2 from the wall surface, and the other of the outward path and the return path of the optical path is formed at a position of W further from the position. Can be easily adjusted.

Further, in the optical voltage sensor according to the fifth aspect of the present invention, as described above, the height of the lead-out portion of the electro-optic crystal with respect to the transparent electrodes formed on the light incident surface and the light emitting surface is formed. It is formed higher by α.

Therefore, in the electro-optic crystal, since there is no conductive adhesive or solder for connecting the lead wire in the portion up to the height H of the other optical component, the electro-optic crystal is connected to the adjacent optical component. Can be assembled in close contact with each other, and it is not necessary to provide an anti-reflection film on the light incident surface and the light exit surface.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a main structure of an optical voltage sensor according to an embodiment of the present invention.

FIG. 2 is a front view of the optical voltage sensor shown in FIG. 1 in an assembled state.

FIG. 3 is a front view showing a main part structure of an assembled state of an optical voltage sensor according to another embodiment of the present invention.

FIG. 4 is an exploded perspective view showing a main structure of a photovoltage sensor according to still another embodiment of the present invention.

FIG. 5 is a front view of the optical voltage sensor shown in FIG. 4 in an assembled state.

FIG. 6 is a front view of an assembled state of an optical voltage sensor according to another embodiment of the present invention.

FIG. 7 is a front view showing a main structure of a typical conventional optical voltage sensor.

FIG. 8 is a front view showing a main structure of another conventional optical voltage sensor.

FIG. 9 is a front view showing the structure of a main part of still another conventional optical voltage sensor.

[Explanation of symbols]

21, 31, 41, 41a Optical voltage sensor 22; 22A, 22B BGO crystal (electro-optic crystal) 22a, 22b; 22Aa, 22Ab, 22Ba, 22
Bb Transparent electrode 23 Optical axis 23a Forward path of optical path 23b Return path of optical path 24, 28, 29 Collimator 25 Polarizer 26; 26A, 26B λ / 8 plate (wave plate) 27 Total reflection prism (total reflection member) 27A, 27B Polarizer (total reflection member) 30 Power supply 34,38 Ball lens

Claims (5)

[Claims] An optical path is formed by providing a polarizer, a wave plate, an electro-optic crystal, and an analyzer, and the electro-optic crystal performs phase modulation on passing light according to an applied voltage or an electric field, and a phase difference between the light and the light. An optical voltage / electric field sensor configured to measure a voltage or an electric field to be measured from a light source, wherein a total reflection member is interposed in the optical path, and the electro-optic crystal is a Bi ₁₂ GeO ₂₀ crystal or Bi ₁₂
As a SiO ₂₀ crystal, only one of the light paths to and from the total reflection member is interposed, and the wavelength plate is a ８ wavelength plate, and is disposed together with the light path to and from the total reflection member. An optical voltage / electric field sensor characterized by the following. 2. An optical path comprising a polarizer, a wave plate, an electro-optic crystal, and an analyzer, wherein the electro-optic crystal performs phase modulation on passing light according to an applied voltage or an electric field, and a phase difference An optical voltage / electric field sensor configured to measure a voltage or an electric field to be measured from a light source, wherein a total reflection member is interposed in the optical path, and the electro-optic crystal is a Bi ₁₂ GeO ₂₀ crystal or Bi ₁₂
SiO ₂₀ formed by two divided in the optical axis direction in the crystal, the crystal axis is interposed each reciprocating optical path to the total reflection member differently at 90 ° each other, the wave plate 1/8 wavelength plate And an optical voltage / electric field sensor, which is disposed together in a reciprocating optical path to the total reflection member. 3. The optical voltage / electric field sensor according to claim 1, wherein a collimator or a ball lens is integrally formed in the polarizer and the analyzer. 4. When the lengths of two mutually orthogonal sides of a light incident surface and a light emitting surface of the rectangular electro-optic crystal are W and H, respectively, the total reflection member and the wavelength plate The lengths of two sides that are orthogonal to each other on the light incident surface and the light emitting surface are 2W and H, respectively. The polarizer and the analyzer each have a length of two sides that are orthogonal to each other on the light incidence and emission surfaces. W, H, the length in the direction of the optical axis is W, or when the polarizer and the analyzer are integrally formed as a polarization analyzer, two sides of the light incidence and emission surfaces that are orthogonal to each other are formed. The optical voltage / electric field sensor according to any one of claims 1 to 3, wherein the length is 2W and H, respectively, and the length in the optical axis direction is 2W. 5. The electro-optic crystal according to claim 1, wherein a transparent electrode is formed on an incident surface and an outgoing surface of the light, and the electro-optic crystal is formed higher in the H direction by a height α of a lead wire. Item 6. The optical voltage sensor according to Item 4.