JPS59116555A - Optical type dc electric field measuring apparatus - Google Patents

Abstract

PURPOSE:To enable measurement of the intensity of DC electric field by employing a method of applying an electric field to an electrooptical crystal and inserting a rotary switch opened or closed by a gas flow or the like in parallel between two vertical surfaces in an electric field detecting section. CONSTITUTION:Electrodes 7-1 and 7-2 are mounted on two surfaces vertical to an electric field E of an electrooptical crystal 7 by vacuum evaporation. The electrooptical crystal 7 and a rotary switch 8 are connected with conductors 9-1 and 9-2 and the rotary switch 8 held with a rotation holding device 12. The potential difference between the conductors 9-1 and 9-2 ranges intermittently from zero to a finite value corresponding to a measuring electric field with the rotation of a rotary switch 8 with a short-circuiting electrode 13 provided on a rotary switch 8. The gas flow for rotation employs N2 gas flow controlled in the temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an electric field measuring device using electro-optic effect, and more particularly to an optical electric field determining device for measuring a direct current electric field.

[Prior art]

Conventional voltage measuring devices and electric field measuring devices that utilize a medium having an electro-optic effect (hereinafter referred to as an electro-optic crystal) are generally limited to alternating current voltages and alternating electric fields. The reason for this is that when an electro-optic crystal is placed in a DC electric field, its capacitance and DC resistance are generally large, so the measured value changes over time, and charge concentration752 occurs on the crystal surface, so-called This is because a surface layer is formed, resulting in poor measurement results.

In the above-mentioned conventional electric field measurement device using an electro-optic crystal (hereinafter referred to as an optical field strength measuring device), an electro-optic crystal is placed in an alternating current electric field, and the crystal changes as the electric field changes. The change in birefringence induced by this is detected as a light intensity signal (alternating current signal) using a polarizer, analyzer, etc., and the change in the electric field is measured. For details, see, for example, "Japanese Patent Publication No. 56-100364, IEICE Technical Research Report, V", 80. A, 6 (1980)
, pages 19 to 24, C) QE80-4, Optical Applied Electric Field Sensor, etc.

The present inventors previously proposed 1 as a method for extending the measurement target of an electric field measuring device using the electro-optic effect to include DC electric fields.
．． They devised a method of rotating the electro-optic crystal itself, and a method of intermittently neutralizing charging charges using the photoconductive effect, and filed applications for each method. However, in the above two methods, 1. 2. Optimize the crystal processing and rotation mechanism so that the amount of light transmitted does not change even when the electro-optic crystal rotates; 2. There are practical problems such as improving the quality so that the effective resistance value of the photoconductor is sufficiently large when not irradiated with light, and improvement measures are desired.

[Object of the Invention] The present invention provides a new optical DC electric field measuring device that solves the above-mentioned difficulties in conventional optical electric field strength measuring devices and makes it possible to measure the strength of a DC electric field. ] In order to achieve the above object, the optical direct current electric field measurement device of the present invention comprises a light source section, an electric field detection section that changes the intensity of light from the light source section in accordance with the electric field intensity, and an electric field detection section that changes the intensity of light from the light source section in accordance with the electric field intensity. It has a measurement section that measures intensity, and a transmission line that optically couples the light source section, the detection section, and the measurement section, and the detection section includes both an electro-optic crystal and a rotary switch.

The rotary switch is used to intermittently neutralize the charge caused by the charge concentration on the surface of the electro-optic crystal. As for this rotary switch, it is preferable to use a rotary switch that uses gas and fluid that does not emit electricity, rather than an electric switch that requires an external power source such as an electric motor. Also,
When using a temperature-controlled gas fluid as this gas fluid,
It is useful to be able to control the temperature of electro-optic crystals.

In the electric field detection section of this optical DC electric field measuring device, the two surfaces of the electro-optic crystal are paired with electrodes and are arranged perpendicular to the applied DC electric field during measurement.

The rotary switch is installed near the electro-optic crystal, and both are connected by a conductor. When the rotary body switch is turned on, a short circuit is created between the two surfaces perpendicular to the electric field, and the charges on the two surfaces are neutralized. On the other hand, when it is open, an electric field is applied to the electro-optic crystal, an electro-optic effect is induced, and a measurement state is established.

The time of this closed state and open state (open time, closed time)
is controlled by the shape and rotation speed of the rotating body switch.

The upper limit of the closed state is not particularly limited, but since the output due to the electro-optic effect disappears when the capacitor is closed, it is determined in consideration of the convenience of measurement. Also, if the charging time is too short, the charged charge will not be able to be discharged sufficiently, causing problems.
There is a lower limit, but this can be determined by a simple experiment to confirm the input time without causing any problems. Further, the upper limit of the open time is the time during which it becomes impossible to measure the stain field intensity due to the charged charge, and can be determined by a simple experiment if necessary. There is no particular lower limit for the open time, but if it is made too short, it will interfere with the measurement of the electric field strength, so the open time is set within a range that does not cause any trouble.

As is well known, it is convenient to use an optical fiber as the optical transmission line.

The light source section usually consists of a light emitting diode and its excitation power source.

The electric field detection unit usually includes a lens, a polarizer, an electro-optic crystal, an analyzer, and a lens in this order between the optical fiber on the light source side and the optical fiber on the measurement unit side, and as described above, the electro-optic crystal and the optical fiber. Rotary switches are arranged in parallel. Further, a λ/4 plate is inserted between the electro-optic crystal and the analyzer, if necessary. In addition to regular analyzers, there are
A polarizing prism such as a Wollaston prism may be used as the polarizer. The number of lenses on the output light side is one in the case of a normal analyzer, and two in the case of a polarizing prism because the light is separated into two linearly polarized lights. The light emitted from the detection section is guided to the light receiver of the measurement section through an optical fiber, and becomes an output electrical signal. This output electric signal may be measured as is, or the light branched between the light source section and the electro-optic crystal (light that does not pass through the electro-optic crystal) and the light from the detection section may be measured using a receiver. The electric field strength may be calculated by converting it into an electric signal and inputting both electric signals to a calculation device. In addition, when a polarizing prism is used as an analyzer, the emitted light is separated into two polarized beams, so both are converted into electrical signals by a photoreceiver.
The electric field strength is calculated by inputting both air pressure signals into a calculation device. Note that the lenses on the incident light side and the exit light side may be omitted.

In any case, the optical DC field measurement device of the present invention is
In the electric field modifying section, the drowsy optical crystal is opened and closed (opened and closed) by gas flow, etc. between two planes perpendicular to the electric field application method.
It is important that the rotary switches are inserted in parallel, and other configurations may follow the conventional technology.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in more detail by way of examples.

FIG. 1 is a configuration diagram of an optical field strength measuring device in this embodiment. It is composed of a light source section 1, an electric field detection section 2, a measurement section 3, and an optical transmission line 4-1.4-2.4-3 that connects them. The light source section 1 includes a light emitting diode 1-1 that emits light with a wavelength of 0.83 μm and its excitation power source 1-2.The field detection section 2 includes a rod lens 2-1.2-
2.2-3, polarizer 5, Wollaston prism 6, electro-optic crystal 7, rotary switch 8, conductor 9-1, 9-2, gas flow introduction pipe 10, gas flow outlet 11, etc. ing. The measuring section 3 includes a PIN photodiode 3-1.
3-2 and the electrical arithmetic and display circuit 30, and the optical transmission line 471.4-2.4-3 is a quartz core, plastic clad optical fiber with a core diameter of 500 μm.

FIG. 2 shows the rotary switch 8 in the electric field detection section of FIG.
, is an explanatory diagram showing the structural relationship of the electro-optic crystal 7 and the structural relationship of the rotary switch 8 and the conductor 9-1, 9-2.

In the power supply section 1, the light from the light emitting diode 1-1 excited by the excitation power supply 1-2 is guided to the electric field detection section 2 through the optical fiber 4-1. In the electric field detection unit 2, the angle between the vibration direction of the light of the polarizer 5 (direction of linear surface light) and the six main axes of the Wollaston prisms is set to 45 degrees. The light beam guided through the original fiber cable 4-1 becomes a linearly polarized parallel light beam by the rod lens 2-1 and the polarizer 5, and enters the electro-optic crystal 7. In the drowsy optical crystal 7, the ellipticity of its birefringent ellipsoid changes in response to the strong repulsion of the electric field E, so that light is emitted from the electro-optic crystal 7 as parallel elliptically polarized light. The emitted light is guided to the Wollaston prism 6, which produces two orthogonal components of linearly polarized light, a rod lens 2-2.2-3, and an optical fiber cable 4-2.4-.
3, the signals are led to PIN photodiodes 3-1 and 3-2, and are converted into drowsiness signals Ps and Pz. The electrical calculation/display circuit 30 performs the following calculation and displays a voltage value according to the external electric field strength.

In the electric field detection section, electrodes 7-1 and 7-2 are attached on two surfaces of the electro-optic crystal 7 perpendicular to the electric field E by vacuum deposition. The electro-optic crystal 7 and the rotary switch 8 are connected by conductors 9-1, 9-2, and the rotary switch 8 is held by a rotary holder 12. Conductor 9-1.9
The potential difference between -2 and 2 is intermittently changed between a finite value and zero according to the measured electric field as the rotary switch 8 rotates due to the short-circuiting electrode 13 provided in the rotary switch 8.

As the rotating gas flow, a N2 gas flow at a temperature of 1 hour was used.

In this example, the opening/closing synchronization of the rotary switch is approximately 100 m when the switch is turned on (closed); approximately 200 m when 8% is opened (open);
I gave it a 5.

Electric field strength measurement is possible only when the rotary switch is open, and when the rotary switch is closed, field strength measurement is in a dormant state. Note that I in FIG. 2(a) indicates the traveling direction of light, and V in FIG. 2(b) indicates the rotation direction of the rotary switch.

As the electro-optic crystal 7, a BjuSi02o single crystal was used. The crystals are (110), (1〒0), (001)
It has a surface and an external size of 5 x 5 x 5 m. The electric field is (
The light was applied in the (110) direction, and the light was propagated in the (110) direction.

FIG. 3 shows actual electric field strength measurement results. Figure 3 shows
This shows that there is a good linear relationship between the DC electric field strength and the drowsiness output of the arithmetic display circuit, and it is clear that the present invention allows measurement of DC electric fields.

〔Effect of the invention〕

According to the present invention, there is an effect that it becomes possible to measure a DC electric field, which was previously impossible.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the entire configuration of an original type DC electric field measuring device according to an embodiment of the present invention, FIG.
b) is an explanatory diagram showing the structural relationship between the rotary switch and the conductor, and FIG. 3 is a graph showing the measurement results of the DC electric field strength by the original type DC electric field measuring device in one embodiment of the present invention. 1... Light source part, 1-1... Light emitting diode, 1-2
...Power source, 2...Electric field detection section, 2-1.2-2.2
-3°...rod lens, 3...measuring section, 3-1.
3-2...PIN photodiode, 4-1. 4-
2.4-3... Optical fiber transmission line, 5... Polarizer,
6... Wollaston prism, 7... Electro-optic crystal, 8... Rotary switch, 9-1.9-2... Conductor,
10...Gas flow introduction pipe, 11...Gas flow outlet, 12...Rotary switch holder, 13...Short circuit electrode, 3o...Calculation display port % 1 See Figure 2 Figure (^ (b)

Claims (1)

[Claims] 1. A light source section, an electric field detection section that changes the intensity of light from the light source section in accordance with the electric field intensity, a measurement section that measures the intensity of light from the detection section, and the light source. an optical transmission line that optically couples the part, the detection part, and the measurement part, and the detection part is equipped with both a medium having an electro-optic effect and a rotary switch. DC electric field measuring device. 2. An optical direct current electric field measuring device according to claim 1, characterized in that a rotating body rotated by a gas flow is used as the rotary switch. 3. An optical DC electric field measuring device according to claim 2, characterized in that a temperature-controlled gas is used as the gas flow.