JPH0727806A - Method and device for detecting electromagnetic noise or leakage wave - Google Patents

Abstract

PURPOSE:To provide such a method for detecting electromagnetic noise or leakage waves that the measuring system itself never products noise or a structure other than a detector nose not catch other noise. CONSTITUTION:Electromagnetic noise or leakage waves are detected as light intensity variation by using a device equipped with an optical probe 100 constituted in such a way that the intensity of light waves transmitted through the probe 100 varies depending upon the strength of the electric field impressed upon the probe 100, optical fiber 8 through which light waves from a light source 1 are made incident on the probe 100, another optical fiber 9 through which light waves transmitted through the probe 100 are made incident on a photoelectric converter 10, and measuring instrument 11 which measures and displays electric signals from the converter 10 and installing the probe near a electromagnetic noise or leakage waves generating source without allowing the probe 100 to come into contact with the source.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for detecting electromagnetic noise or electromagnetic leakage waves.

[0002]

2. Description of the Related Art The development of electronics, especially computer equipment and digital equipment, causes a flood of electromagnetic leakage waves and noise, which is becoming a social problem. Therefore, suppression of electromagnetic noise is a social demand, and at the same time, high probability of advanced detection and measurement technology is desired.

Conventionally, a method of detecting electromagnetic noise or electromagnetic leakage waves (hereinafter simply referred to as noise) in space has been adopted in which an antenna captures the electromagnetic noise and guides it through a wire cable to a measuring instrument for detection / measurement.

A noise evaluation test of an electronic component or a device equipped with a device is performed by the method using the antenna, and a detection method using an oscilloscope has been adopted for detecting a voltage waveform of a circuit.

Further, there is also known a method of detecting the potential of a surface of a semiconductor element or the like and the waveform of noise by converting an electric field thereof into an intensity of light by an electro-optical effect by bringing an electro-optical crystal (EO crystal) close to the surface. ing.

[0006]

A wide space is required for detecting noise by the antenna. This method can easily detect radiation noise from other than the measurement target.

Measurement of spatial noise by this antenna,
In the measurement of the voltage waveform of the circuit by the oscilloscope probe, the detection signal is guided by a wire cable from the detector to the measuring instrument. When using a wire cable, it may itself be a source of noise or trap noise from others. Furthermore, the presence of the detector and the wire cable itself may affect the electric field distribution in space or in the system. As far as these possibilities are concerned, these conventional techniques cannot be regarded as measuring the true state.

On the other hand, the surface electric field detection method utilizing the electro-optical effect described above is characterized in that the voltage or noise waveform on the minute surface of the circuit element is measured in a non-contact manner. FIG. 5 shows a surface electric field detection method utilizing the electro-optical effect. Electro-optic crystal 51 emitted from the semiconductor laser 50 is collimated by a lens 52, passes through a polarizing prism 53 and a half-wave plate 54, is reflected by a mirror 55, and is placed by a lens 56 near a circuit 58 to be measured. It is incident on 57. The polarization state of the incident light changes in the crystal due to the electric field applied from the measured circuit 58, and the change is due to the change.
Are separated by the light detector 59 and detected by the photodetector 59, and the display 60
Is displayed in.

Usually, this optical system is incorporated in a microscope to eliminate mechanical instability, and a measurable circuit 58 to be measured is a circuit on a flat substrate such as a wafer or a chip. This method requires a large optical system including a polarization prism and the operation of spatially propagating the light beam to the circuit under test 58, and therefore requires a narrow space inside an electronic component or a device equipped with a device. It is difficult to measure at.

An object of the present invention is to provide an electromagnetic noise or electromagnetic leak wave detecting method and apparatus which can solve these problems of the above-mentioned prior art. That is, the present invention realizes a small-sized detector, and therefore enables detection of an electric field and noise in a narrow space, generates noise in the measurement system itself, and a component other than the detector captures other noise. Provided is a method and apparatus for detecting electromagnetic noise or electromagnetic leakage waves, which can measure the electric field on the surface of a circuit element in a non-contact manner without causing the measurement system to affect the system to be measured. Especially.

[0011]

According to the present invention, an optical probe configured so that the intensity of a transmitted light wave changes depending on the intensity of an applied electric field; a light source for generating a light wave; A first optical fiber that guides and makes the light wave from the light source enter the optical probe; a photoelectric converter that converts the light wave into an electric signal; a second optical fiber that guides and makes the light wave that has passed through the optical probe enter the photoelectric converter. An optical fiber; and a measuring instrument for measuring and / or displaying an electric signal from the photoelectric converter; A method for detecting electromagnetic noise or electromagnetic leakage waves is provided, which detects electromagnetic noise or electromagnetic leakage waves as a change in light intensity by installing them in the vicinity of them without touching them. That.

Further in accordance with the present invention, the optical probe comprises:
A method for detecting electromagnetic noise or electromagnetic leakage waves is obtained, which comprises: a substrate having an electro-optical effect; and an optical waveguide element arranged on the substrate.

Further, according to the present invention, there is provided a structure in which the incident light incident on the one end face of the optical waveguide is reflected by the other end face of the optical waveguide and is emitted as the emitted light from the one end face. An optical probe configured to depend on the strength of an applied electric field; a light source for generating light; an optical fiber; a photoelectric converter for converting light into an electric signal; and a light from the light source for the optical fiber. A circulator that guides to the optical probe as the incident light and gives the emitted light from the optical probe received through the optical fiber to the photoelectric converter; and an electric signal from the photoelectric converter. A measuring device for measuring or / and displaying; and a device for detecting electromagnetic noise or a leaky wave, the optical probe being provided in the vicinity thereof without contacting the source of the electromagnetic noise or the leaky wave. Detection method of electromagnetic noise or electromagnetic leakage wave is obtained and detecting the electromagnetic noise or electromagnetic leakage wave as light intensity changes by location.

Further, according to the present invention, the leak electric field applied between the signal line of the electric circuit and the ground is detected by the optical probe in a non-contact manner. Is obtained.

Further, according to the present invention, an optical probe constructed so that the intensity of the transmitted light wave changes depending on the intensity of the applied electric field; a light source for generating the light wave; and a light wave from the light source. A first optical fiber for guiding the light to the optical probe for incidence; a photoelectric converter for converting a light wave into an electric signal;
A second optical fiber that guides the light wave that has passed through the optical probe into the photoelectric converter for incidence; and a measuring device that measures and / or displays an electrical signal from the photoelectric converter; An electromagnetic noise or electromagnetic leak wave detection device is provided which is characterized in that the electromagnetic noise or electromagnetic leak wave is detected as a change in light intensity by being installed in the vicinity of the electromagnetic noise or leak wave generation source without contacting the electromagnetic noise or leak wave generation source.

Further in accordance with the invention, the optical probe comprises:
An electromagnetic noise or electromagnetic leak wave detecting device is obtained, which comprises: a substrate having an electro-optical effect; and an optical waveguide element arranged on the substrate.

Further, according to the present invention, there is provided a structure in which the incident light incident on the one end face of the optical waveguide is reflected on the other end face of the optical waveguide and is emitted as the emitted light from the one end face, and the intensity of the emitted light is An optical probe configured to depend on the strength of an applied electric field; a light source for generating light; an optical fiber; a photoelectric converter for converting light into an electric signal; and a light from the light source for the optical fiber. A circulator that guides to the optical probe as the incident light and gives the emitted light from the optical probe received through the optical fiber to the photoelectric converter; and an electric signal from the photoelectric converter. A measuring instrument for measuring or / and displaying; and by installing the optical probe in the vicinity of the electromagnetic noise or leaky wave generation source without contacting the electromagnetic noise or leaky wave, Detector of electromagnetic noise or electromagnetic leakage wave and detecting a change in light intensity is obtained.

Further, according to the present invention, the leaky electric field applied between the signal line of the electric circuit and the ground is detected by the optical probe in a non-contact manner. Is obtained.

[0019]

The electromagnetic noise or electromagnetic leakage wave detecting method and apparatus according to the present invention detects the change in the intensity of the light wave passing through the optical probe depending on the intensity of the electric field.
That is, electromagnetic noise or electromagnetic leakage waves are detected as a change in light intensity. In the present detection method and apparatus, electromagnetic noise or electromagnetic leakage waves are converted into light and detected, and the light is transmitted to the photoelectric converter by the optical fiber, where it is first transmitted as an electric signal to the measuring instrument. Therefore, in this transmission line system using an optical fiber, there is no transmission or reception of electromagnetic noise or electromagnetic leakage waves, and the existence of this measurement system itself does not affect the system under measurement.

[0020]

Embodiments of the present invention will now be described with reference to the drawings.

[Embodiment 1] FIG. 1 shows the configuration of an apparatus used for carrying out an electromagnetic noise or electromagnetic leak wave (hereinafter simply referred to as noise) detection method according to an embodiment of the present invention. FIG. 2 is an enlarged view of the optical probe 100 in FIG. 1 and shows changes in input light and output light together.

In the optical probe 100, an optical waveguide is constructed on a lithium niobate crystal substrate 2 which is an electro-optical crystal, an electrode 3 is formed in the vicinity thereof, and the electrode 3 is connected to an antenna 4 integrated with the optical probe 100. Laser light from the semiconductor laser 1 is introduced into the incident waveguide 5 of the optical probe by the optical fiber 8. The output of the optical probe 100 is separately transmitted to the photoelectric converter 10 through the connecting optical fiber 9, converted into an electric signal here, and further, the noise detection device is configured so that the noise can be measured and displayed by the measuring device 11. .

More specifically, the optical probe 100 includes an optical waveguide which is branched from the incident optical waveguide 5 into two phase-shifting optical waveguides 6 and is then re-coupled, and electrodes installed near these phase-shifting optical waveguides 6. The antenna 4 is connected to the antenna 3. The noise captured by the antenna 4 generates an electric field in the phase shift optical waveguide 6 and locally causes a change in the refractive index. Therefore, a phase difference occurs in the light wave propagating between the two phase shift optical waveguides 6 and It is detected as a change in light intensity at the output end of the waveguide 7.

The detection sensitivity of the electric field of the optical probe 100 decreases as the length of the antenna 4 decreases, but the antenna length is 14 m.
The minimum sensitivity at m was 1 mV / m, and an electric field of 10 V / m or more could be measured. Further, when the antenna length is shortened, the sensitivity is lowered but the high electric field can be measured.

FIG. 3 shows an example in which the noise detecting device having the above-mentioned structure is applied to the measurement of noise radiated by a vehicle equipped with a gasoline engine. An optical probe 100 is connected to the tip of an optical fiber 8 connected to a laser light source including a semiconductor laser 1, and light emitted from the optical probe 100 is connected to a photoelectric converter (photodetector) 10 via an optical fiber 9 for measurement. The noise waveform detected by the measuring device 11 is displayed.
We measured the noise level in each of the engine room and the control unit equipped with a microcomputer, and confirmed that the waveform of the electromagnetic noise could be detected faithfully.

An optical probe having an optical waveguide constructed on a lithium tantalate crystal substrate which is an electro-optical crystal was also used. As a result, the detection sensitivity of the electric field strength was the same as that of the optical probe constructed on the lithium niobate crystal substrate.

[Embodiment 2] FIG. 4 shows the construction of an apparatus used for carrying out another method of noise detection according to the present invention.

In the present embodiment, the optical probe 100 'is a reflection type, and the total reflection film 20 is provided on the end face of the phase shift optical waveguide. The outputs of the incident light and the reflected light are transmitted by one polarization maintaining optical fiber 21, and the electrode 23 formed near the optical waveguide 22 also serves as an antenna. The circulator 24 guides the light from the laser light source including the semiconductor laser 1 to the optical fiber 21, and the optical probe 100
′ As incident light, and the emitted light from the optical probe 100 ′ received via the optical fiber 21 is given to the photoelectric converter 10. Reference numerals 25 and 26 are lenses. The size of the optical probe 100 'used in this example is 3 × 25.
It was × 0.2 mm.

The noise detecting device having the above-mentioned configuration was applied to the noise measurement in the device in which the circuit board is mounted and operated. An optical probe was inserted between a number of printed circuit boards with electrical circuits, and the usefulness was confirmed by measuring the electric field and noise in a narrow space between the boards.

[Embodiment 3] Based on the configuration of the apparatus shown in FIG. 4, the signal waveform of the leakage electric field applied between the signal line of the electric circuit formed on the printed circuit board and the ground is shown in FIG. Non-contact detection was performed by the optical probe 100 '. Since the optical probe 100 'has a flat sensitivity characteristic from a measurement frequency of DC to several GHz, a signal waveform in that band can be faithfully reproduced. Further, since the distance between a signal line or an electric component on a normal printed board and the ground wire is several mm or less, the electric field strength of a minute area on the printed board surface is 0.1 V /
It becomes m to 10 KV / m, and it is possible to sufficiently detect even a probe with an effective short antenna length that also serves as an antenna as an electrode. Similarly, by using the optical probe 100 shown in FIG. 2, the signal waveform of the leakage electric field applied between the signal line of the electric circuit formed on the printed board and the ground can be detected in a non-contact manner.

[0031]

As compared with the conventional method of detecting noise by an electric method and measuring it as an electric signal, the present invention detects the change in the intensity of a light wave passing through an optical probe depending on the intensity of an electric field. Lightwave signals are transmitted from the detection system to the measurement system. This enables contactless detection, downsizing of the detector, and because the glass fiber replaces the wire cable, the transmission line emits noise,
Or lost receiving. In addition, it was possible to eliminate the conventional harmful effects that the existence of the wire cable caused to change the electric field distribution of the system.

The leakage electric field applied between the signal line of the electric circuit formed on the printed circuit board or the like and the ground can be detected in a non-contact manner, and the result can be applied to the circuit design at any time.

These dramatically improve the reliability of the noise detection technique.

The present invention contributes to the progress of electromagnetic noise reduction technology, which is a social demand, and to the raising of public awareness.

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus for implementing a method for detecting electromagnetic noise or electromagnetic leakage waves according to an embodiment of the present invention.

FIG. 2 is an enlarged view of the optical probe shown in FIG. 1, which also shows changes in input light and output light.

FIG. 3 is a diagram showing an example in which the apparatus of FIG. 1 is applied to measurement of noise radiated by a vehicle equipped with a gasoline engine.

FIG. 4 is a block diagram of an apparatus for implementing a method for detecting electromagnetic noise or electromagnetic leakage waves according to another embodiment of the present invention.

FIG. 5 is a block diagram of an apparatus for implementing a conventional method for detecting electromagnetic noise or electromagnetic leakage waves.

[Explanation of symbols]

 1 Semiconductor Laser 2 Lithium Niobate Crystal Substrate 3 Electrode 4 Antenna 5 Incident Optical Waveguide 6 Phase Shift Optical Waveguide 7 Emitting Optical Waveguide 8, 9 Optical Fiber 10 Photoelectric Converter 11 Measuring Instrument 12 Wire Cable 20 Total Reflection Film 21 Polarization-Maintaining Light Fiber 22 Optical waveguide 23 Electrode 24 Circulator 25, 26 Lens

Claims (8)

[Claims] 1. An optical probe configured so that the intensity of a transmitted light wave changes depending on the intensity of an applied electric field; a light source for generating the light wave; and a light wave from the light source to the optical probe. A first optical fiber for guiding and entering the light; a photoelectric converter for converting a light wave into an electric signal; a second optical fiber for guiding and entering the light wave transmitted through the optical probe into the photoelectric converter; and from the photoelectric converter And a measuring device for measuring and / or displaying the electric signal of the electromagnetic noise or the leaky wave, and the optical probe is installed in the vicinity of the electromagnetic noise or the leaky wave source without contacting the source. A method for detecting electromagnetic noise or electromagnetic leakage waves, characterized by detecting electromagnetic noise or electromagnetic leakage waves as a change in light intensity. 2. The electromagnetic noise or the electromagnetic leakage wave according to claim 1, wherein the optical probe includes a substrate having an electro-optical effect; and an optical waveguide element arranged on the substrate. Detection method. 3. The optical waveguide has a structure in which incident light incident on one end face of the optical waveguide is reflected on the other end face of the optical waveguide and is emitted as outgoing light from the one end face, and the intensity of the outgoing light depends on the applied electric field. An optical probe configured to depend on intensity; a light source for generating light; an optical fiber; a photoelectric converter for converting the light into an electrical signal; and guiding light from the light source to the optical fiber, A circulator that gives the incident light to the optical probe as the incident light and gives the emitted light from the optical probe received through the optical fiber to the photoelectric converter; and measures and / or displays an electric signal from the photoelectric converter. And a measuring device for measuring the electromagnetic noise or the leakage wave, the optical probe is installed in the vicinity of the electromagnetic noise or the leakage wave source without contacting the source. A method for detecting electromagnetic noise or electromagnetic leakage waves, which comprises detecting electromagnetic noise or electromagnetic leakage waves as a change in light intensity. 4. A leak electric field applied between a signal line of an electric circuit and a ground is detected by the optical probe in a non-contact manner. A method of detecting electromagnetic noise or electromagnetic leakage waves. 5. An optical probe configured so that the intensity of a transmitted light wave changes depending on the intensity of an applied electric field; a light source for generating the light wave; and a light wave from the light source to the optical probe. A first optical fiber for guiding and entering the light; a photoelectric converter for converting a light wave into an electric signal; a second optical fiber for guiding and entering the light wave transmitted through the optical probe into the photoelectric converter; and from the photoelectric converter And a measuring instrument for measuring and / or displaying an electric signal of the electromagnetic wave, and by arranging the optical probe in the vicinity of the electromagnetic noise or the leakage wave generation source without contacting the electromagnetic noise or the electromagnetic leakage wave, An electromagnetic noise or electromagnetic leak wave detection device characterized by being detected as a change. 6. The electromagnetic noise or the electromagnetic leakage wave according to claim 5, wherein the optical probe includes a substrate having an electro-optical effect; and an optical waveguide element arranged on the substrate. Detection device. 7. A structure is provided in which incident light that has entered one end face of the optical waveguide is reflected by the other end face of the optical waveguide and is emitted as outgoing light from the one end face, and the intensity of the outgoing light is the same as the applied electric field. An optical probe configured to depend on intensity; a light source for generating light; an optical fiber; a photoelectric converter for converting the light into an electrical signal; and guiding light from the light source to the optical fiber, A circulator that gives the incident light to the optical probe as the incident light and gives the emitted light from the optical probe received through the optical fiber to the photoelectric converter; and measures and / or displays an electric signal from the photoelectric converter. And a measuring instrument for controlling the electromagnetic noise or the leaked wave as a light intensity change by installing the optical probe in the vicinity of the electromagnetic noise or the leaked wave generation source without contacting the source. A device for detecting electromagnetic noise or electromagnetic leakage waves, which is characterized by being emitted. 8. A leak electric field applied between a signal line of an electric circuit and a ground is detected by the optical probe in a non-contact manner. A device for detecting electromagnetic noise or electromagnetic leakage waves.