GB2342160A - Electrooptic probe - Google Patents

Electrooptic probe Download PDF

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Publication number
GB2342160A
GB2342160A GB9922506A GB9922506A GB2342160A GB 2342160 A GB2342160 A GB 2342160A GB 9922506 A GB9922506 A GB 9922506A GB 9922506 A GB9922506 A GB 9922506A GB 2342160 A GB2342160 A GB 2342160A
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GB
United Kingdom
Prior art keywords
electro
diodes
photo
optic
reflection
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB9922506A
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GB2342160B (en
GB9922506D0 (en
Inventor
Mitsuru Shinagawa
Tadao Nagatsuma
Toshiyuki Yagi
Akishige Ito
Junzo Yamada
Katsushi Ohta
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ando Electric Co Ltd
Nippon Telegraph and Telephone Corp
Original Assignee
Ando Electric Co Ltd
Nippon Telegraph and Telephone Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to JP29456898 priority Critical
Application filed by Ando Electric Co Ltd, Nippon Telegraph and Telephone Corp filed Critical Ando Electric Co Ltd
Publication of GB9922506D0 publication Critical patent/GB9922506D0/en
Publication of GB2342160A publication Critical patent/GB2342160A/en
Application granted granted Critical
Publication of GB2342160B publication Critical patent/GB2342160B/en
Anticipated expiration legal-status Critical
Expired - Fee Related legal-status Critical Current

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Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R13/00Arrangements for displaying electric variables or waveforms
    • G01R13/20Cathode-ray oscilloscopes
    • G01R13/22Circuits therefor
    • G01R13/34Circuits for representing a single waveform by sampling, e.g. for very high frequencies
    • G01R13/347Circuits for representing a single waveform by sampling, e.g. for very high frequencies using electro-optic elements
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R1/00Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
    • G01R1/02General constructional details
    • G01R1/06Measuring leads; Measuring probes
    • G01R1/067Measuring probes
    • G01R1/07Non contact-making probes
    • G01R1/071Non contact-making probes containing electro-optic elements
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R15/00Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
    • G01R15/14Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
    • G01R15/24Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices
    • G01R15/241Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-modulating devices using electro-optical modulators, e.g. electro-absorption

Abstract

An electro-optic probe for an oscilloscope with improved sampling accuracy includes a laser diode (11) for emitting modulated light according to control signals from the electro-optic sampling oscilloscope; a lens for collimating the light (10); an opto-electronic element (2), having a reflection film at one end (2a), which changes optical properties in response to electric fields propagated through a metal pin (1a) contacting the reflection end; an isolator device (16) between the collimating lens and the opto-electronic element, having polarizing beam splitters (61, 91) for transmitting the light emitted from the laser diode and separating a reflected beam produced at the reflection film into signal beams; photo-diodes (14, 15) for converting the separated beams into respective electrical signals; and sections (61a, 91a, 17a, 17b) respectively disposed so as to prevent internal reflections from entering the photo-diodes through the polarizing beam splitters. The reflection prevention sections comprise of reflective or refractive surfaces or a painted black or porous surface.

Description

2342160 ELECTRO-OPTIC PROBE
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates in general to electro-optic probes for observing waveforms of target signals according to polarization states produced by coupling electric fields formed by the target signals to an electro-optic crystal and injecting light into the electro-optic crystal, and relates in particular to an electro-optic probe having an improved optical system.
This application is based on a patent application No. Hei 10-294568 filed in Japan, the content of which is incorporated herein by reference.
Description of the Related Art
It is possible to observe waveforms of target signals, produced by coupling electric fields formed by the target signals to an optoelectronic crystal, and injecting laser light into the crystal and observing the polarization states of the laser light. If the laser light is pulsed, the target signals can be analyzed chronologically with a fine resolution. This phenomenon is utilized in electro-optic probes for use in electro-optic sampling oscilloscopes to analyze circuit performance in fine detail.
Electro-optic sampling oscilloscope (shortened to EOS oscilloscope) has received much attention because of the following special features of the instrument, compared to an oscilloscope using a normal electric probe:
(1) signal measurement is facilitated because a ground line is not required; 2 (2) there is virtually no effect on the behavior of the target signals because the metal pin used at the tip of the electro-optic probe is electrically isolated from the circuit system to provide a high input impedance: and (3) bandwidth of the measurable range is increased to a GHz range because of the use of optical pulses.
Figure 2 shows a construction of a conventional electro-optic probe system comprised by: a probe head 1 made of an electrical insulator having a metal pin la inserted in the center thereof; an electro-optic (e- o) crystal 2 having a reflection film 2a at the reflection-end, which is in electrical contact with the metal pin la; collimating lenses 3, 10; a half-wave plate 4; a quarter-wave plate 5; polarizing beam splitters 6, 9; a half-wave plate 7; a Faraday element 8 for rotating the polarized plane of the injected light 45 degrees; a laser diode 11 for generating modulating laser light in response to control signals output from a pulsing circuit (not shown) provided in the main body 19 of the EOS oscilloscope; collimating lenses 12, 13; pboto-diodes 14, 15 for converting the modulated laser light to electrical signals and outputting the electrical signals to the main body 19 of the EOS oscilloscope; an isolator device 16 comprised by the half-wave plates 4, 7, the quarterwave plate 5, the polarizing beam splitters 6, 9 and the Faraday element 8; and a probe casing 17 made of an electrical insulator.
Next, the optical path of the laser light generated from the laser diode 11 will be explained with reference to Figure 2. In Figure 2, incident laser beam is indicated by a letter A.
First, laser light emitted from the laser diode 11 is converted to a parallel beam of light by the collimating lens 10, and propagates in a straight line through the polarizing beam splitter 9, Faraday element 8, half-wave plate 7, polarizing beam splitter 6, and into the quarter-wave plate 5 and the half-wave plate 4, and is focused by the collimating lens 3 to enter the e-o element 2. Incident light is reflected by the reflection film 2a formed on the surface at the reflection-end of the e-o element 2.
3 The reflected light is again converted to a parallel beam of light by the collimating lens 3, and passes through the half-wave plate 4, and quarter- wave plate 5 to enter the polarizing beam splitter 6, where a portion of the reflected beam is reflected and focused by the collimating lens 12 and enters photo-diode 14. At the same time, some of the light reflected from the reflection film 2a transmits through the polarizing beam splitter 6, and is reflected at the polarizing beam splitter 9, focused by the collimating lens 13 and enters photo-diode 15.
The quarter-wave plate 4 is for equalizing the intensities of the laser beams entering the photo-diodes 14, 15. The half-wave plate 4 is for equalizing the intensities of the laser beams entering the e-o element 2, and the half-wave plate 7 is for aligning the optical axes of the polarizing beam splitters, 6, 9.
The operation the electro-optic probe shown in Figure 2 to measure target signals will be explained in the following.
When the metal pin la contacts a measuring point, Pockeles' effect is generated by the voltage applied to the metal pin la, thereby altering the birefringence of the e-o element 2 due to piezo-electric effect. This causes changes in the polarization states of the incident laser light emitted from the laser diode 11 and propagated through the e-o element 2. The incident beam, with altered polarization states, is reflected by the reflection film 2a, and the signal beams produced at the beam splitters 6, 9 are converted to electrical signals in the photo-diodes 14, 15.
As the voltage of the measuring point changes with time, such timedependent changes are manifested in the changes in the polarization states, resulting in differences in the output signals from the photodiodes 14, 15, thereby determining waveform of the target signals being sensed by the metal pin la.
4 In the operation of the electro-optic probe explained above, the electrical signals obtained from the photo-diodes 14, 15 are input in the conventional EOS oscilloscope for processing; however, instead of this approach, it is possible to measure target signals by connecting the photo-diodes 14, 15 to dedicated controllers and determining the waveforms using a conventional real-time measuring oscilloscope. This process permits measurements over a broad range of bandwidths using an electro-optic probe.
However, the design of the probe for the conventional sampling oscilloscope produces a problem of internal reflections, as indicated by the optical paths B, C in Figure 2, which are caused by inadequate extinction ratios of the beam splitters 6, 9, resulting in transmission of some portion of the reflected light that should have been transmitted through the reflection surfaces 6b, 9b. The transmitted light is further reflected by the interior surfaces of the probe casing 17 and can enter photo-diodes 14, 15 to produce optical noise in the converted electrical signals, resulting in poor signal-to-noise ratio, S/N, which ultimately show up as random errors in the measurements.
Also, it is not only difficult to improve the extinction ratios of the beam splitters 6, 9, but such efforts will result in increasing the cost of the optical parts.
SUMMARY OF THE ITSTWNTION
It is an object of the present invention to provide an electro-optic probe for an oscilloscope that enables to reduce parasitic reflections inside the probe casing so as to increase the S/N ratio of measured data.
The object has been achieved in a probe comprised by:
a laser diode for emitting a laser light according to control signals generated in a main body of the electro-optic sampling oscilloscope; a collimating lens for converting the laser light to a parallel beam; an opto-electronic element, having a reflection film at a reflection-end, that changes optical properties in response to electric fields propagated through a metal pin contacting the reflection-end; isolator means, disposed between the collimating lens and the opto-electronic element, having polarizing beam splitters for transmitting the laser light emitted from the laser diode and separating a reflected beam produced at the reflection film into signal beams; photo-diodes for converting optical energies of the signal beams separated by the isolator means into respective electrical signals; and internal reflection prevention sections respectively disposed so as to prevent parasitic reflections from entering the photo-diodes through the polarizing beam splitters.
Additionally, because the internal reflection prevention section is provided on the interior surface of the probe casing, internally reflected beams are directed away from the photo-diodes so that parasitic reflections are prevented from affecting the waveform determinations, thereby improving the S/N ratio of the sampling scope.
The object has also been achieved in a modification of the basic probe comprised by: a laser diode for emitting a laser light according to control signals generated in a main body of the electro-optic sampling oscilloscope; a collimating lens for converting the laser light to a parallel beam; an opto-electronic element, having a reflection film at a reflection-end, that changes optical properties by electric fields propagated through a metal pin contacting the reflectionend;
6 isolator means, disposed between the collimating lens and the optoelectronic element, comprised by polarizing beam splitters for transmitting the laser light emitted from the laser diode and separating a reflected beam produced at the reflection film into signal beams; and photo-diodes for converting optical energies of the signal beams separated by the isolator means into respective electrical signals; wherein the polarizing beam splitters are provided with respective refracting surfaces, which are fabricated so that refracted beams escaping from refracting surfaces are not directed to photo-diodes.
Additionally, the refracting surfaces of the polarizing beam splitters are fabricated so that even if escaping rays that should have transmitted through the beam splitters are produced at their reflection surfaces, optical axis of the escaping rays is at an angle to the signal beam entering the photo-diodes to avoid creating noise in the photo-conversion conversion process.
It should be noted that the reference numerals appended to particular components in the claims do not limit the technical interpretation of the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic diagram of an embodiment of the electro-optic probe of the present invention.
Figure 2 is a schematic diagram of an electro-optic probe for a conventional design of EOS oscilloscope.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
7 An embodiment of the present design of the electro-optic probe (referred to as the probe hereinbelow) for an oscilloscope will be presented in the following with reference Figure 1.
Those components of the probe that are the same as those in the conventional probe shown in Figure 2 will be given the same reference numerals and their explanations will be omitted. The present probe differs from the conventional probe in the following respects. Irregular bumps are formed on the refracting surface 61a of the beam splitter 61, and a slanted refracting surface 91a is formed on the beam splitter 91. Also, a first internal reflection prevention section 17a having a slanted reflection surface and a second internal reflection prevention section 17b having a bumpy reflection surface are provided on the inside surface of the probe casing 17.
The optical path of the laser light emitted from the laser diode 11 will be explained with reference to Figure 1. In Figure 1, the optical path of the laser light emitted from the laser diode 11 is shown by a letter D.
First, the laser light emitted from the laser diode 11 is converted into a parallel beam of light by the collimating lens 10, and is propagated in a straight line through the polarizing beam splitter 91, Faraday element 8, half-wave plate 7, polarizing beam splitter 61, and into the quarter- wave plate 5, and the half-wave plate 4.
Next, the parallel beams that transits the half-wave plate 4 is condensed by the collimating lens 3, is incident on the electro-offic (e-o) crystal 2, and reflected by the reflection film 2a formed on the end surface of the electro-optic (e-o) crystal 2 on the side facing the metal pin la.
Because the collimating lens 3 is placed at its focal point, the parallel beam produced by the collimating lens 10 focuses at one point on the reflection film 2a.
8 The signal beam produced at the reflection film 2a is again converted to a parallel beam in the collimating lens 3, is passed through the halfwave plate 4, quarter-wave plate 5, and is separated by the beam splitters 61, 91 to produce signal beams which enter respective photo- diodes 14, 15 where they are converted to electrical signals.
Next, the optical paths of the laser light emitted from the laser diode 11 and reflected from the reflection surfaces 61b, 91b of the beam splitters 61, 91 to result in escaping rays E will be explained.
First, a portion of the signal beam produced at the reflection surface 61b of the beam splitter 61 escapes from the refracting surface 61a of the beam splitter 61, but because the escaping rays E is scattered by the bumps formed on the refracting surface 61a, it is prevented from entering the photo-diode 14 even if it is reflected back from the interior surface of the probe casing 17.
Furthermore, the first internal reflection prevention section 17a is provided opposite the photo-diode 14 on the interior surface of the probe casing 17 so that its slanted reflection surface is not oriented at right angles to the escaping rays E arriving from the reflection surface 61b. Because of the slanted surface, incident beam traveling straight to the surface of the internal reflection prevention section 17a is directed away from the photodiode 14.
In this case, the angle of slant of the internal reflection prevention section 17a is selected by optics of the escaping rays E exiting the beam splitter 61 so that the re-directed rays will be outside the angle of view of the photo-diode 14.
In the meantime, escaping rays E produced at the reflection surface 91a of the beam splitter 91 is directed away from the photo-diode 15 by the slanted refracting surface 91a of the beam splitter 91. Therefore, the escaping rays E also do not enter the photo-diode 15.
9 Furthermore, the second internal reflection prevention section 17b is provided opposite the photo-diode 15 on the interior surface of the probe casing 17 so that its bumpy reflection surface scatters escaping rays E arriving in a straight line from the reflection surface 91b. Because of the bumpy surface on the internal reflection prevention section 17b, scattered reflections traveling straight to the surface of the internal reflection prevention section 17b are directed away from the photo-diode 15.
In this case, the slanting angle of the slanted refracting surface 91a of the beam splitter 91 is chosen by optics of the escaping rays F exiting the beam splitter 91 so that the re-directed rays will be outside the angle of view of the photo-diode 15 by appropriate selection of the exiting angle of the escaping rays F, and the index of refraction of the material for the beam splitter 91.
Accordingly, parasitic reflections inside the probe casing 17 are prevented, by providing a bumpy refracting surface 61a and a slanted refracting surface 91a on the refracting surfaces of the respective beam splitters 61, 91 so as to tilt the optical axes of the escaping rays exiting from the beam splitters, and by further providing internal reflection prevention sections 17a, 17b on the interior surface of the probe casing 17, thus resulting in improving the S/N ratio.
In the configuration shown in Figure 1, all the features of the present probe, i.e., a bumpy refracting surface 61a on the beam splitter 61, a slanted planar surface 91a on the beam splitter 91, slanted planar surface 17a and a bumpy surface 17b on the probe casing 17, however, it is acceptable to provide at least one of these features to obtain the effect of improving the S/N ratio.
For example, internal reflection prevention sections 17a, 17b may be omitted and either a bumpy refracting surface 61a or a slanted refracting surface 91a may be provided.
Also, cube-shaped beam splitters 6, 9 shown in Figure 2 may be used in place of the beam splitters 61, 91 shown in Figure 1, in conjunction with the internal reflection prevention section 17a or l7b.
Also, instead of the slanted surface or bumpy surface used for the respective internal reflection prevention sections 17a, 17b, the interior surface of the probe casing 17 may be painted black or coated with a porous material to reduce internal reflections.
It should be noted in the above embodiments that if the output light from the laser diode 11 is continuous, waveform measurements can also be performed using a general purpose conventional instrument such as realtime oscilloscope, sampling oscilloscope, or spectrum analyzer. In such a case, the laser diode 11 generates laser light according to a cW laser source, and the photo-diodes 14, 15 are connected to respective dedicated controllers, so that the target signals can be measured by conventional instrument by way of the dedicated controllers, instead of an EOS oscilloscope.
On the other hand, by arranging the electro-optic system so that the laser diode generates laser light according to control signals from a light generating/measuring oscilloscope, either an EOS oscilloscope or a real-time oscilloscope can be used to extend the measuring range to wide bandwidths.

Claims (11)

What is claimed is:
1. An electro-optic probe for an oscilloscope comprising: a laser diode (11) for emitting a laser light according to control signals generated in a main body of said electro-optic sampling oscilloscope; a collimating lens (10) for converting the laser light to a parallel beam; an optoelectronic element (2), having a reflection film (2a) at a reflection-end, that changes optical properties in response to electric fields propagated through a metal pin (1a) contacting said reflection-end; isolator means (16), disposed between said collimating lens (10) and said optoelectronic element (2), comprised by polarizing beam splitters (61, 91) for transmitting said laser light emitted from said laser diode (11) and separating a reflected beam produced at said reflection film (2a) into signal beams; photo-diodes (14, 15) for converting optical energies of said signal beams separated by said isolator means (16) into respective electrical signals; and internal reflection prevention sections (17a, 17b) respectively disposed so as to prevent parasitic reflections from entering said photo-diodes (14, 15) through said polarizing beam splitters (61, 91).
2. An electro-optic probe according to claim 1, wherein an internal reflection prevention section (17b) is provided with an irregular reflection surface so as to direct escaping rays away from photo-diodes (14, 15).
3. An electro-optic probe according to claim 1, wherein an internal reflection prevention section (17a) is provided with a slanted planar surface, which is oriented so as to direct escaping rays away from said photo-diodes (14, 15).
12
4. An electro-optic probe according to one of claims 1 to 3, wherein photo-diodes and a laser diodes are connected to an electro-optic sampling oscilloscope, and said laser diode generates pulsed light according to control signals produced by said electro-optic sampling oscilloscope.
5. An electro-optic probe according to one of claims 1 to 3, wherein said laser diode is a continuous-wave laser source.
6. An electro-optic probe for an oscilloscope comprising: a laser diode (11) for emitting a laser light according to control signals generated in a main body of said electro-optic sampling oscilloscope; a collimating lens (10) for converting the laser light to a parallel beam; an optoelectronic element (2), having a reflection film (2a) at a reflection-end, which changes optical properties in response to electric fields propagated through a metal pin (1a) contacting said reflection-end; isolator means (16), disposed between said collimating lens (10) and said optoelectronic element (2), comprised by polarizing beam splitters (61, 91) for transmitting said laser light emitted from said laser diode (11) and separating a reflected beam produced at said reflection film (2a) into signal beams; and photo-diodes (14, 15) for converting optical energies of said signal beams separated by said isolator means (16) into respective electrical signals; wherein said polarizing beam splitters (61, 91) are provided with respective refracting surfaces (61a, 91a), which are fabricated so that refracted beams escaping from refracting surfaces are directed away from photo-diodes (14, 15).
7. An electro-optic probe according to claim 4, wherein said refracting surface (61a) is fabricated as an irregular refracting surface so as to direct escaping rays away from photodiodes (14, 15).
13
8. A probe for an electro-optic sampling oscilloscope according to claim 4, wherein said refracting surface (91a) is fabricated as a slanted planar surface so as to direct escaping rays away from photo-diodes (14, 15).
9. An electro-optic probe according to one of claims 6 to 8, wherein photo-diodes and a laser diodes are connected to an electro-optic sampling oscilloscope, and said laser diode generates pulsed light according to control signals produced by said electro-optic sampling oscilloscope.
10. An electro-optic probe according to one of claims 6 to 8, wherein said laser diode is a continuous-wave laser source.
11. An electro-optic probe substantially as herein described with reference to and as illustrated in Figure 1 of the accompanying drawings.
GB9922506A 1998-09-30 1999-09-24 Electro-optic probe Expired - Fee Related GB2342160B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP29456898 1998-09-30

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GB9922506D0 GB9922506D0 (en) 1999-11-24
GB2342160A true GB2342160A (en) 2000-04-05
GB2342160B GB2342160B (en) 2000-12-13

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DE (1) DE19946665A1 (en)
GB (1) GB2342160B (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2346692A (en) * 1999-02-12 2000-08-16 Ando Electric Electro-optic probe
GB2361059A (en) * 1999-12-28 2001-10-10 Ando Electric Reduction of light noise in an electro-optic probe
GB2369432A (en) * 2000-07-05 2002-05-29 Ando Electric Electro-optic probe and magneto-optic probe
CN102360131A (en) * 2011-09-29 2012-02-22 中国科学院上海光学精密机械研究所 Multifunctional high-power polarization preserving fiber isolator

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2217443A (en) * 1988-04-08 1989-10-25 Hamamatsu Photonics Kk Voltage detector using electro-optic material
GB2245970A (en) * 1990-06-23 1992-01-15 Graviner Ltd Kidde Particle detector for gaseous fluids
GB2277376A (en) * 1993-04-09 1994-10-26 Hochiki Co Light scattering type smoke detector
US5537247A (en) * 1994-03-15 1996-07-16 Technical Instrument Company Single aperture confocal imaging system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2217443A (en) * 1988-04-08 1989-10-25 Hamamatsu Photonics Kk Voltage detector using electro-optic material
GB2245970A (en) * 1990-06-23 1992-01-15 Graviner Ltd Kidde Particle detector for gaseous fluids
GB2277376A (en) * 1993-04-09 1994-10-26 Hochiki Co Light scattering type smoke detector
US5537247A (en) * 1994-03-15 1996-07-16 Technical Instrument Company Single aperture confocal imaging system

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2346692A (en) * 1999-02-12 2000-08-16 Ando Electric Electro-optic probe
GB2346692B (en) * 1999-02-12 2001-02-21 Ando Electric Electro-optic probe
US6410906B1 (en) 1999-02-12 2002-06-25 Ando Electric Co., Ltd. Electro-optic probe
GB2361059A (en) * 1999-12-28 2001-10-10 Ando Electric Reduction of light noise in an electro-optic probe
GB2361059B (en) * 1999-12-28 2002-08-07 Ando Electric Electro-optic probe
GB2369432A (en) * 2000-07-05 2002-05-29 Ando Electric Electro-optic probe and magneto-optic probe
US6624644B2 (en) 2000-07-05 2003-09-23 Ando Electric Co., Ltd. Electro-optic probe and magneto-optic probe
CN102360131A (en) * 2011-09-29 2012-02-22 中国科学院上海光学精密机械研究所 Multifunctional high-power polarization preserving fiber isolator

Also Published As

Publication number Publication date
GB2342160B (en) 2000-12-13
GB9922506D0 (en) 1999-11-24
DE19946665A1 (en) 2000-05-18

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Effective date: 20030924