Abstract: A device, system and method for monitoring a switchable load operably coupled to a positionable switch. The device including a face plate mountable on the positionable switch, a sensor mounted on the face plate, wherein the sensor is configured to detect the position of the positionable switch and electronics mounted on the face plate and operably coupled to the sensor, wherein the electronics are configured to determine the amount of time the positionable switch has been in a given position.

Abstract: An electromagnetic survey sensing device includes at least two electrodes disposed at spaced apart locations. An electrical to optical converter is electrically coupled to the at least two electrodes. The converter is configured to change a property of light from a source in response to voltage imparted across the at least two electrodes. The device includes an optical fiber optically coupled to an output of the electrical to optical converter, the optical fiber in optical communication with a detector.

Abstract: A polarizing optical system (15, 16) is disposed perpendicular to an optical axis of incoming light from a light source (12), having the optical axis (12) as a center axis, and configured for polarization of incoming light to a prescribed reference state, an electro-optical device (17) is disposed perpendicular to the optical axis, having the optical axis as a center axis, and adapted, as a voltage to be measured is imposed thereon, to respond to the imposed voltage by polarizing light polarized by the polarizing optical system (15, 16), and an analyzer (18) is disposed perpendicular to the optical axis, having the optical axis as a center axis, and adapted for detection of light polarized by the electro-optical device (17), to irradiate a detector (21) configured for conversion of incoming light into an electric signal.

Abstract: The electric field measuring device measures an electric field intensity of an electromagnetic wave generated from equipment under test 8 in an area for detecting an electromagnetic wave. An antenna 1 and an optical intensity modulator having a Mach-Zehnder type optical waveguide are inside the area and an output signal of the antenna is supplied to a modulation electrode of the optical intensity modulator. A light source unit, a light receiving unit, and a DC bias control unit controlling a DC bias voltage supplied to the optical intensity modulator are outside the area. An optical wave is guided to the optical intensity modulator from the light source unit, and is guided to the light receiving unit from the optical intensity modulator via an optical fiber 4. The DC bias voltage is supplied to the optical intensity modulator from the DC bias control unit via a power supply line 4.

Abstract: The present invention provides an inspecting apparatus for photovoltaic devices which electrifies the photovoltaic devices in a forward direction thereof to make the photovoltaic devices emit electro-luminescence light and which has a simple-structured and cheap darkroom. The inspecting apparatus of the present invention includes a darkroom 110 provided with a flat upper surface 111, a transparent plate 112 which is provided in the upper surface of the darkroom for disposing the photovoltaic devices as an inspecting object 200, a camera 120 which is provided in the darkroom and a driving mechanism to move the camera in the darkroom.

Abstract: A sensor device includes sensor elements arranged in a matrix form, and a sensor driving section driving the sensor elements. Each of the sensor elements includes a photoelectric conversion element generating electric charge, a storage node storing electric charge, to show a voltage which fluctuates according to the stored electric charge, a reset transistor resetting the voltage in the storage node and a readout section reading the voltage value resulted from the stored electric charge in the storage node, to output the resultant voltage value. The sensor driving section controls the reset transistor so that the storage nodes of the sensor elements over sensor element lines are reset into the predetermined reset voltage at a time, and then performs read control after a lapse of a predetermined exposure period to allow the sensor detection signals to be sequentially outputted from the respective sensor elements arranged in each sensor element lines.

Abstract: The present invention provides a solar simulator that measures characteristics of multi junction photovoltaic devices for a short time, and a measuring method of a multi-junction photovoltaic devices using the simulator.

Abstract: An optical fiber electric current sensor includes a polarization-splitter (13) that splits light outputted from a sensor fiber (11) into two polarization planes of which polarization directions are perpendicular to each other, a depolarizer (17) that depolarizes each of the polarization components from the polarization-splitter (13), light receiving element that converts the two lights that were depolarized by the depolarizer (17) to a first signal (S1) and a second signal (S2) respectively, and a signal processing unit (15) that, based on the first signal (S1) and the second signal (S2), determines the magnitude of a Faraday rotation applied to the linearly-polarized light, and thereby calculates a value of the current to be measured.

Abstract: Pulses of signals in the terahertz region are generated using an apparatus made up of a mode-locked semiconductor laser diode with a short duty cycle that is optically coupled to a biased Auston switch. The output from the mode-locked semiconductor laser diode may first be supplied to a pulse compressor, and the resulting compressed pulses supplied to the Auston switch. Preferably, the mode-locking of the semiconductor laser diode is controllable, i.e., it is an active mode-locking semiconductor laser, so that the phase of the output optical signal from the laser is locked to the phase of an input control signal.

Abstract: The object of the invention is to provide a method and a system for fixating a Faraday optical current sensor (12a, 12b, 12c) in a suitable measurement position for measuring the current in a 3-phase cable (14). The 3-phase cable (14) comprises 3 individual section-shaped phase conductors (16a, 16b, 16c) insulated in relation to one another and encapsulated inside an insulator (18). The method comprises the provision of a Faraday optical current sensor arrangement comprising 3 Faraday optical current sensors (12a, 12b, 12c), each Faraday optical current sensor being fixated in a specific position outside the section-shaped phase conductors (16a, 16b, 16c), and the provision of a processing unit for calculating a current value from a magnetic field value.

Abstract: A method is provided to improve the usability of Design-For-Testability Synthesis (DFTS) tools and to increase the design process productivity. The method comprises receiving a list of testability and design impact analysis functions, to be performed on the circuit, also referred to as a device under test (DUT). The impact analysis leads to the creation of logical transformations, which can be selected by a user with one or more available transformation methods from a list including, but not limited to, boundary scan test logic insertion, scan test logic insertion, memory BIST (built-in-self-test) logic insertion, and logic BIST logic insertion, and scan test data compression insertion logic insertion.

Abstract: A universal, wireless, nano-optical voltmeter comprises an organic core having at least one voltage-sensitive dye and at least one polymeric shell substantially surrounding the organic core. The nano-optical voltmeter can detect electric fields in cells. The nano-optical voltmeter allows three-dimensional E field profiling throughout the entire volume of living cells. The nano-optical voltmeter may be calibrated externally and then applied for E field determinations inside any live cell or cellular compartment, with no further calibration steps.

Abstract: An apparatus, for measuring an electric field while minimally perturbing the electric field being measured, includes an analyzing stage and a sensor head. The sensor head is optically coupled to the analyzing stage by a laser probe beam transmitted from the analyzing stage. The sensor head includes an electro optic crystal disposed between two gradient index lenses, where the first gradient index lens emits a laser beam transmitted from the analyzing stage to the sensor head, where the electric field is applied and where, the electro optic crystal transforms the laser beam probe into a phase modulated laser beam. The second gradient index lens transmits the phase modulated laser beam back to the analyzing stage, where polarization optics and a photodetector convert the phase modulated laser beam into an electrical signal representing field strength and phase of the electric field.

Abstract: A method is provided for tuning the fiber optic retarder of a fiber optic current sensor towards a desired temperature dependence, the sensing fiber is exposed to a magnetic field or corresponding electric current and the sensor signal as well as the signal's dependence on the retarder temperature are measured. From this initial sensor signal and its temperature dependence, a target sensor signal can be determined, at which the dependence on the retarder temperature equals a desired value. Then, the retarder is thermally treated until the sensor signal reaches the target value. The method obviates the need for repetitively measuring the temperature dependence during the tuning process.

Abstract: A fiber optic current or magnetic field sensor uses a sensing fiber in a coil for measuring a current or a magnetic field and has a retarder for converting between linearly polarized light and elliptically polarized light. The retardation of the retarder; its temperature dependence as well as its azimuth angle in respect to the plane of the fiber coil are optimized in dependence of the birefringence in the sensing fiber in order to minimize the influence of temperature variations and manufacturing tolerances on the overall scale factor of the sensor.

Abstract: A voltage sensor includes two optical sensing fibers and a control unit. The sensing fibers carry a first mode of light and a second mode of light, which are orthogonally polarized, with a birefringence between the two modes depending on the electric voltage to be measured. The control unit is configured to generate light for the two modes in the sensing element and to measure the phase delay suffered between the two modes. A 45° Faraday rotator is arranged between the control unit and the sensing fibers. The Faraday rotator allows the behavior and functionality of the sensing fibers and their associated components to be converted to those of a magneto-optical current sensors with polarization-rotated reflection, which in turn allows use of advanced measuring techniques developed for optical gyroscopes and current sensors.

Abstract: A Faraday optical current sensor arrangement for measuring the current through a power line comprises a Faraday optical current sensor (38) having an elongated and substantially cylindrical shape defining a first end and a second end opposite the first end. The Faraday optical current sensor has a first optical conduit (48) extending from the first end and a second optical conduit (48) extending from the second end. Furthermore, the Faraday optical current sensor arrangement comprises a hollow housing (12,14) enveloping the Faraday optical current sensor and fixating the Faraday optical current sensor in a specific measurement position relative to the hollow housing. The hollow housing defines a channel for accommodating the Faraday optical current sensor and the first and second optical conduits and an opening (15) for communicating with the channel.

Abstract: Two transversely poled fibers are disclosed which can be wound around a holder with their poling directions being anti-parallel. A coupling exchanges the polarization directions of the modes of the fibers. Thermally and mechanically caused birefringence changes can thereby be substantially cancelled, while electrical field induced birefringence changes can be added, to provide a more robust high voltage measuring device.

Abstract: A method and a circuit for tracking maximum power of a photo-voltaic array performs the operation of load increase/decrease with a preset current difference and determines if the photo-voltaic array operates at zone A or zone B based on change of the output voltage before and after the operation to decide the next operation being for load increase or load decrease. It is not necessary for tracking the maximum power with the multiplier to estimate the output power of the photo-voltaic array. Therefore, the circuit for tracking the maximum power of the photo-voltaic array is capable of being simplified and joined to the pulse width modulation circuit to form an integrated circuit with a function of tracking the maximum power.

Abstract: A system may include acquisition of power information from a signal line in accordance with a first signal characteristic. The power information is associated with power generated by a solar collector, and the first signal characteristic is substantially orthogonal to a corresponding signal characteristic of at least one noise source associated with the signal line. In some aspects, a solar tracking error associated with the solar collector is determined based on the acquired power information, a servo feedback signal is determined based on the acquired power information, and determination of the solar tracking error includes determination of the solar tracking error based on the servo feedback signal.

Abstract: The invention relates to a device, a probe, and a method for the galvanically decoupling transmission of a measuring signal. A microwave signal is supplied by a transceiver (1) to a sensor (3) by means of a galvanically decoupled waveguide (2). The signal is partially reflected in the sensor (3), the amplitude, phase and/or polarization of the reflected microwave signal containing the information relating to the measuring value. The reflected microwave signal runs through the same waveguide (2) back to the transceiver (1) and is evaluated therein. The invention provides a more simple and economical structure than conventional devices of prior art, as a voltage supply is not required especially on the sensor side as a result of the reflection. In this way, the sensor (3) can also be produced in a very compact manner, minimizing the influence of the measuring signal through the sensor (3).

Abstract: Disclosed is an optical fiber for a current sensor, the optical fiber comprising a core doped with CdSe quantum dots and a current sensor using the same.

Abstract: An adapter device for applying a fiber-optic monitoring system to a component to be monitored includes a shell adapted to surround the component to be monitored, the shell having a rounded exposed surface onto which a first optical fiber of the fiber-optic monitoring system can be wrapped.

Abstract: The present invention relates to a sensor for the detection of an analyte, comprising a fluid holder (8), an optical detection system (3, 9) for carrying out an optical detection at the fluid holder (8) and an electrical detection system (4) for measuring electric conductivity or resistance inside the fluid holder (8) and to a method comprising the use of such a sensor.

Abstract: An apparatus includes an optical resonator and a passive optical device. The optical resonator has first and second optical reflectors and an optical cavity interposed between the reflectors. The optical resonator includes an electro-optically responsive material. One of the reflectors is a distributed Bragg reflector. A passive optical device is configured to direct light through the first optical reflector. The optical resonator is configured to return a portion of the light through the first reflector.

Abstract: A monitoring circuit of the present invention provides a monitor signal with which a magnitude of a current flowing across a photodetector, such as a photodiode, can be calculated accurately over a wide temperature range on the basis of a value of the monitor signal. The monitoring circuit of the present invention includes: a current mirror circuit for outputting a monitor current proportional to an input current, the current mirror circuit having an input point for receiving the input current, the input point being connected to a photodetector and a load resistor, which are connected thereto in parallel; and an output circuit for outputting a monitor signal indicating a difference between a monitor electric potential proportional to the monitor current, and an offset electric potential proportional to an offset current which flows across the load resistor concurrently with the monitor current.

Abstract: An apparatus for testing a semiconductor device having an RF shield has a shield box. A test board is positioned in an interior of the shield box. A first surface of the test board has an area for attaching the semiconductor device. A shield device is attached to a second surface of the test board and beneath the area for attaching the semiconductor device. An antenna is positioned in the interior of the shield box and above the area for attaching the semiconductor device.

Abstract: An arrangement for measuring an internal clock within an electricity meter includes an optical communication circuit within the meter, an optical detector external to the meter, and a frequency counter. The optical communication circuit within the electricity meter is operably coupled to receive a pulse output of the meter's internal clock, and is further configured to generate a corresponding optical pulse representative of the pulse output. The optical detector is configured to detect the pulse output via an optical port of the electricity meter. The frequency counter is operably coupled to receive from the optical detector a signal that is representative of the detected pulse output.

Abstract: An apparatus includes an optical resonator and a passive optical device. The optical resonator has first and second optical reflectors and an optical cavity interposed between the reflectors. The optical resonator includes an electro-optically responsive material. One of the reflectors is a distributed Bragg reflector. A passive optical device is configured to direct light through the first optical reflector. The optical resonator is configured to return a portion of the light through the first reflector.

Abstract: Particle detection and characterising apparatus has an insulating tube (50) along which the particles flow. Five electrodes (51, 52, 55, 56) and (57) spaced along the outside of the tube are connected via amplifiers (61) and (62) to a processor (68) arranged to measure the charge on the particles. The apparatus also includes a laser (11) and photomultiplier tube (23) arranged to measure the size of the particles so that the nature of the particles can be characterised from their electrical charge and size.

Abstract: Failure analysis method includes performing fixed radiation of semiconductor chip (wafer) by photocurrent generation laser beam, scanning and radiating a region to be observed on semiconductor chip by heating laser beam, detecting, by a SQUID fluxmeter, current change generated in the semiconductor chip by radiating the photocurrent generation laser beam and the heating laser beam, and analyzing failure of the semiconductor chip based on current change detected by the SQUID fluxmeter. Radiation of photocurrent generation laser beam and heating laser beam are performed from a back surface side of the LSI chip, and detection by the SQUID fluxmeter is performed on a front surface side of the LSI chip. In analysis of failure of the LSI chip, image processing is performed in which a signal outputted from the SQUID fluxmeter is made to correspond to a scanning point. Visualization of defects is possible.

Abstract: The present invention relates to a Faraday sensor assembly comprising a first light guiding element adapted to guide electromagnetic radiation along a first propagation direction, and a second light guiding element adapted to guide electromagnetic radiation along a second propagation direction, the second propagation direction being essentially oppositely arranged relative to the first propagation direction. The Faraday sensor assembly further comprises a measurement region arranged between the first and second light guiding elements, the measurement region being adapted to receive an electrically conducting element having, in the measurement region, its primary extension direction in a direction being essentially perpendicular to the first and second propagation directions. The present invention further relates to methods and systems for stabilizing output signal from the sensors, and to methods and systems for processing signals from the sensor assembly.

Abstract: The disclosure provides for a method for identifying and measuring a signal pulse induced in a microcircuit due to ionizing radiation. The method comprises locating an ionizing radiation induced pulse across a microcircuit using a plurality of sensors on the microcircuit. The method further comprises radiating a radiation through the microcircuit to produce a pulse width. The method further comprises using a time to digital converter (TDC) to measure a duration of the pulse width to create a measured pulse width. The method further comprises using the TDC to convert the measured pulse width into a digital signal.

Abstract: An optical fiber electric current sensor includes a polarization splitter (13) that splits output light from a sensor fiber (11) into two polarization components of which polarization planes intersect with each other; and a signal processing unit (15) that converts the two split polarization components into first and second signals (Px) and (Py) by opto-electric conversion, multiplies a ratio (Sx) between direct current component and alternating current component of the first signal (Px) and a ratio (Sy) between direct current component and alternating current component of the second signal (Py) by different coefficients, and calculates a difference value therebetween.

Abstract: A simple constitution together with an easy calibration of output by realizing a fast light intensity detection method is realized without using the carrier signal. An optical sensor, including: a sensor to which light from a light source is lead, and by which light intensity of the light is modulated based on a physical value; light receiving elements 61 and 62 receiving two elements of divided light PA and PB having polarized waves which are orthogonally crossing each other; a variable optical attenuator operating light which is received by the light receiving elements 61 and 62; and a variable amplifier operating output signals from the light receiving elements 61 and 62, wherein both a zero point of a sensor output and sensitivity are calibrated based on a light attenuation factor or an amplification factor which is adjusted when a physical value is detected by calculating a ratio between a sum and a difference of outputs of the light receiving elements 61 and 62.

Abstract: A time-stretched enhanced recording scope (TiSER) is described using time stretch analog-to-digital conversion in a real-time burst mode. A chirped optical signal is modulated in response to receiving segments of an input signal. The optical signal with its modulated input signal, is stretched through an optical medium and digitized to represent the waveform segment. TiSER provides ultra-fast real-time sampling within short segment bursts of the original input signal while providing an ability to detect non-repetitive events. Methods and apparatus are also described for providing real-time information about inter-symbol information (ISI), rapidly determining bit-error rates (BER), performing time-domain reflectometry (TDR), generating eye diagrams for serial data, facilitating digital correction of data, clock recovery, optical carrier phase recovery, and otherwise increasing the speed and/or accuracy of a diverse range of high-speed signal measurement and processing activities.

Abstract: The current invention provides a shunt defect detection device that includes a device under test (DUT) that is fixedly held by a thermally isolating mount, a power source disposed to provide a directional bias condition to the DUT, a probe disposed to provide a localized power to the DUT from the power source, an emission detector disposed to measure a temporal emission from the DUT when in the directional bias condition, where the measured temporal emission is output as temporal data from the emission detector to a suitably programmed computer that uses the temporal data to determine a heating rate of the DUT and is disposed to estimate an overheat risk level of the DUT, where an output from the computer designates the DUT a pass status, an uncertain status, a fail status or a process to bin status according to the overheat risk level.

Abstract: A sensor array for detecting the content of a fluid sample comprises first and second electrodes having connections for a drive signal. The first electrode is coated with a layer of a first material having optical properties which change according to the electrical charge passing through it or the potential across it. Sensor sites are defined by islands of a second material such that the charge passing through or the potential across the second material, in response to the drive signal, varies according to the fluid sample composition.

Abstract: In a reflection type optical fiber electric current measurement apparatus, a standardization reference signal (Xr), which is defined by the intensity (Pr) of the optical reference signal transmitted through a partial transmission mirror by using a reflector (111B) provided in one end of a sensor fiber as the partial transmission mirror, is subtracted from a standardization detection signal (Xs), which is defined by the intensity (Ps) of the optical detection signal obtained from the light reflected at the partial transmission mirror. Thereby, it is possible to remove noise caused by fluctuation in the polarization state (B) as well as fluctuation in the luminescence intensity (A) of the light source.

Abstract: The invention concerns an arrangement for monitoring electrical equipment for the emergence of accidental arcs. The object is to more reliably recognize the occurrence of an arc on lines, cables and/or contact sites or in devices than has been possible with previously known solutions. The proposed arrangement comprises at least one electrical conductor, which connects devices, subassemblies or circuit components of the piece of electrical equipment with one another, at least one light guide or optical fiber which guides the light arising in the formation of an arc to an optical/electrical transformer, as well as a monitoring and evaluating unit electrically connected with the transformer. The optical fiber envelops one or more wire cores of the above-mentioned electrical conductor and thus simultaneously forms the electrical insulation of a line or the shielding of a cable.

Abstract: Disclosed are a method and system for evaluating current spreading of a light emitting device. The method includes applying current to a light emitting device and acquiring a luminescence image corresponding to a digital signal, converting the luminescence image into a gray image, and determining the number of pixels having gray levels greater than a set threshold among pixels included in the luminescence image converted into the gray image, as a criterion for determining the degree of current spreading of the light emitting device. The luminescent area of the light emitting device is quantified as an objective value on the two-dimensional plane by using an image processing technique, so that the degree of current spreading in the light emitting device can be evaluated.

Abstract: The present invention provides an optical sensor for monitoring current or power in a monitored element of a device such as a bridge-wire or hot-wire of electro-explosive devices. The optical sensor comprises an optical sensor made of semiconductor material. The semiconductor material comprises an absorption edge which is sensitive to a temperature variation. The semiconductor material is for placing in thermal contact with the monitored element of the device, whereby, when the current or power varies in the monitored element, it causes a variation in temperature in the semiconductor element and hence a spectral shift of the absorption edge which can be measured and which is representative of current and power variation.

Abstract: An image sensor has a plurality of pixels, each pixel having a photodiode (12), a voltage amplifier (16) having gain greater than 1 and a sampling capacitor (18) charged by the voltage amplifier. In this arrangement, each pixel provides gain through voltage amplification. This enables the sampling capacitor (18) to be kept to a low size, so that the pixel circuitry occupies the smallest possible space, thereby enabling large aperture pixels to be formed.

Abstract: The present invention relates to a measuring instrument for a photovoltaic system; the system is of the type comprising at least one photovoltaic module (FM1; FM2) and at least one conversion module (CM1; CM2) connected to the output of the photovoltaic module (FM1; FM2); the instrument comprises first measuring means (MM1, MM3) adapted to be connected to the photovoltaic module (FM1; FM2) and to determine electric generation efficiency values, as well as second measuring means (MM1, MM2) adapted to be connected to the conversion module (CM1; CM2) and to determine electric conversion efficiency values.

Abstract: A junction-photovoltage method and apparatus for contactless determination of an electrical/physical parameter of a semiconductor structure having at least one p-n junction located at a surface is disclosed. In one aspect, the method includes illuminating the surface with the p-n junction with a light beam of a first wavelength to create excess carriers at the surface. The method also includes modulating the light intensity of the light beam at a single predefined frequency. The method also includes determining a first photo-voltage at a first position inside the illuminated area and a second photo-voltage at least a second position outside the illuminated area. The method also includes calculating an electrical/physical parameter of the semiconductor structure based on the first and second photo-voltage.

Abstract: A gradation image capture is used to test one or more image sensors. The integration periods for the rows of pixels in the array, or for groups of rows of pixels, are varied during each single still frame image capture. The S rows of pixels are reset either simultaneously or successively to a predetermined level, and then begin accumulating charges. The rows of pixels, or groups of rows of pixels, are read out at different times to vary the integration periods of the pixels. Some or all of the signals are analyzed or measured to detect any design or manufacturing problems.

Abstract: In order to extend the measurement range of a current sensor, a current divider is formed by a first conductor formed in a current sensor that is mounted on a printed circuit board and a second conductor on the printed circuit board that electrically shorts at least one input terminal of the current sensor to at least one output terminal of the current sensor. The input terminal of the current sensor supplies the current to be measured to the first conductor and the output terminal supplies the measured current back to the printed circuit board.

Abstract: A detector for an ultraviolet lamp system of the type having a microwave generator includes a first circuit that is configured to detect the microwave energy generated from the microwave generator. The first circuit includes at least one radiation sensitive component capable of failing upon exposure to an excessive amount of microwave energy. A second circuit is coupled to the first circuit and configured to intermittently test whether the radiation sensitive component has failed. An ultraviolet lamp system includes the detector. An associated method includes monitoring the microwave energy through the first circuit including at least one radiation sensitive component capable of failing upon exposure to an excessive amount of microwave energy and testing the radiation sensitive component to determine whether the radiation sensitive component has failed.

Abstract: An optical sensor configuration contains an optical current sensor and/or an optical voltage sensor. The sensor configuration further contains a first and a second hollow member, preferably ring shaped profiles, which are together disposed to form a hollow section. The sensor configuration further includes an optical fiber of the current sensor disposed in an annular groove, the groove being disposed at the boundary surface between the first hollow member and the second hollow member, and/or an optical fiber of the voltage sensor is disposed in a recess of the second hollow member. The first hollow member has an annular recess into which the second hollow member is disposed whereas the first hollow member is an L-shaped or U-shaped ring with two legs and the recess is formed between the two legs.

Abstract: An optical voltage transformer is connected with an external electric device and includes a primary electrode to which a measured voltage is applied by the external electric device, a first secondary electrode provided oppositely to the primary electrode, an insulation layer provided between the primary and first secondary electrodes and constituting an insulation cylinder integrally formed with the primary and first secondary electrodes, a ground layer provided on an outer circumference of the insulation cylinder and around the first secondary electrode for securing a capacitance by interposing the insulation layer between the ground layer and the first secondary electrode, and an electro-optic element for measuring a voltage between the first secondary electrode and the ground layer.