US20020011830A1 - Electro-optical probe for oscilloscope measuring signal waveform - Google Patents
Electro-optical probe for oscilloscope measuring signal waveform Download PDFInfo
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- US20020011830A1 US20020011830A1 US09/448,525 US44852599A US2002011830A1 US 20020011830 A1 US20020011830 A1 US 20020011830A1 US 44852599 A US44852599 A US 44852599A US 2002011830 A1 US2002011830 A1 US 2002011830A1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R13/00—Arrangements for displaying electric variables or waveforms
- G01R13/20—Cathode-ray oscilloscopes
- G01R13/22—Circuits therefor
- G01R13/34—Circuits for representing a single waveform by sampling, e.g. for very high frequencies
- G01R13/347—Circuits for representing a single waveform by sampling, e.g. for very high frequencies using electro-optic elements
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- This invention relates to electro-optical probes used for oscilloscopes that use electro-optical crystals to measure waveforms of signals based on electro-optical effects, and particularly to electro-optical probes used for electro-optic sampling oscilloscopes.
- electro-optic sampling oscilloscopes operate as follows:
- Electro-optical crystals on which laser beams are incident.
- electro-optical crystals on which laser beams are incident.
- the laser beams are formed in a pulse-like form, so that it is possible to measure waveforms of the signals with a very high resolution with respect to time.
- the electro-optic sampling oscilloscopes use electro-optical probes, which work based on the known electro-optical phenomenon.
- EOS electro-optic sampling oscilloscopes
- a metal pin provided at a tip end of the electro-optical probe is insulated from the circuitry, so it is possible to realize high input impedance. Therefore, it is possible to perform measurement without substantially disturbing states of measuring points.
- the EOS oscilloscope uses optical pulses for the measurement. So, it is possible to perform the measurement in a broad band, a frequency range of which is increased up to Giga-Hertz (GHz) order.
- GHz Giga-Hertz
- FIG. 3 shows a probe unit 15 of the EOS oscilloscope, which is equipped with a probe head 1 made of an insulator.
- a metal pin 1 a is installed at a center of the probe head 1 .
- An electro-optical element (i.e., electro-optical crystal) 2 is equipped with a reflector (or reflection mirror) 2 a , which is formed at a terminal surface facing with an end of the metal pin 1 a and is brought into contact with the metal pin 1 a.
- the probe unit 15 contains collimator lenses 3 , 10 , half-wavelength (or 1 ⁇ 2 wavelength) plates 4 , 7 , a quarter-wavelength (or 1 ⁇ 4 wavelength) plate 5 , polarizing beam splitters 6 , 9 , and a Faraday rotator 8 , which rotates a polarizing plane of incident light by 45 degrees.
- the probe unit 15 contains a laser diode 11 , which radiates laser beams in response to a control signal output from a main body of the EOS oscilloscope (not shown), as well as photodiodes 12 , 13 , which convert incoming laser beams to electric signals. Those electric signals are output to the main body of the EOS oscilloscope.
- the probe unit 15 contains an optical isolator 14 a, which is configured by the half-wavelength plates 4 , 7 , quarter-wavelength plate 5 , beam splitters 6 , 9 and Faraday rotator 8 .
- the collimator lens 10 converts the laser beams output from the laser diode 11 to parallel beams, which propagate straight through the polarizing beam splitter 9 , Faraday rotator 8 , half-wavelength plate 7 and polarizing beam splitter 6 sequentially in a forward direction. They also pass through the quarter-wavelength plate 5 and half-wavelength plate 4 sequentially. Thereafter, the parallel beams are converged together by the collimator lens 3 and are then incident on the electro-optical element 2 as its incoming beams. The incoming beams of the electro-optical element 2 are reflected by the reflector 2 a, which is formed at the terminal surface of the electro-optical element 2 facing with the metal pin 1 a.
- reflected beams are converted to parallel beams by the collimator lens 3 .
- the parallel beams propagate through the half-wavelength plate 4 and quarter-wavelength plate 5 in a backward direction. A part of the parallel beams is reflected by the polarizing beam splitter 6 and is incident on the photodiode 12 .
- the parallel beams that transmit through the polarizing beam splitter 6 are reflected by the polarizing beam splitter 9 and are incident on the photodiode 13 .
- the quarter-wavelength plate 4 is provided to make adjustment such that strength of incoming laser beams of the photodiode 12 coincides with strength of incoming laser beams of the photodiode 13 .
- the half-wavelength plate 4 is provided to adjust a polarizing plane of an incoming beam of the electro-optical element 2 .
- the electric signals produced by the photodiodes 12 , 13 of the EOS probe are input to the EOS oscilloscope, in which they are processed.
- the EOS oscilloscope it is possible to use some conventional measurement devices such as the real-time oscilloscope.
- the measurement device is connected to the photodiodes 12 , 13 by way of a dedicated controller so as to perform measurement on signals. That is, the EOS probe can be widely used for the measurement devices to enable broad-band measurement on the signals with ease.
- the aforementioned EOS oscilloscope is designed to separate the incoming beams of the electro-optical element 2 , which are brought by the optical isolator 14 a, from the reflected beams which are reflected by the reflector 2 a.
- Such a design causes a problem in which a number of optical parts constructing the optical isolator 14 a is increased.
- an electro-optical probe of this invention is provided for an electro-optic sampling oscilloscope, which is designed as follows:
- Electric fields caused by measured signals are connected with an electro-optical crystal, on which optical pulses produced based on timing signals are incident and in which the optical pulses are changed in polarization states.
- the electro-optic sampling oscilloscope is capable of measuring waveforms of the measured signals based on changes of the polarization states.
- this invention provides an improvement in an optical system of the electro-optical probe.
- the electro-optical probe is mainly constructed by a probe head and a probe unit.
- the probe head contains a metal pin being brought into contact with a measuring point to detect an electric field caused by the measured signal and an electro-optical element having a reflector at its terminal surface facing with an end of the metal pin.
- the probe unit contains a reduced number of optical parts, which are arranged such that an optical axis of incoming beams of the electro-optical element differs from a optical axis of outgoing beams of the electro-optical element.
- laser beams radiated from a laser diode propagate along a first optical path and are subjected to convergence by a converging lens to produce converged beams, which are incident on the electro-optical element as its incoming beams.
- the incoming beams are subjected to reflection by the reflector to produce reflected beams, which are output from the electro-optical element as its outgoing beams along a second optical path.
- the first and second optical paths are selected not to be in parallel with each other.
- the beams are changed in polarization states in response to the electric field. Then, the reflected beams output from the electro-optical element are converted to parallel beams by a collimator lens and are then input to a polarization detector. Or, they are converged by a converging lens and are then input to the polarization detector.
- the polarization detector performs separation on the input beams thereof to produce separated components of beams, optical axes of which differ from each other.
- a first component of beams substantially corresponding to the input beams is incident on a first photodiode, while a second component of beams corresponding to a part of the input beams is incident on a second photodiode.
- the first and second photodiodes respectively output electric signals.
- FIG. 1 is a schematic illustration partially in section showing a construction of an electro-optical probe used for an electro-optic sampling oscilloscope in accordance with embodiment 1 of the invention
- FIG. 2 is a schematic illustration partially in section showing a construction of an electro-optical probe used for the electro-optic sampling oscilloscope in accordance with embodiment 2 of the invention.
- FIG. 3 is a schematic illustration partially in section showing a construction of an electro-optical probe used for the conventional electro-optic sampling oscilloscope.
- FIG. 1 shows a configuration of an electro-optical probe of an electro-optic sampling oscilloscope in accordance with embodiment 1 of the invention.
- FIG. 1 shows internal configurations of a probe head 1 and a probe unit 15 , wherein parts equivalent to those shown in FIG. 3 are designated by the same reference numerals, hence, the description thereof will be omitted according to needs.
- the probe unit 15 shown in FIG. 1 is configured using a polarization detector 14 , which is provided for separation of polarization components.
- the polarization detector 14 is configured by the aforementioned quarter-wavelength plate 5 and polarizing beam splitter 6 without using the aforementioned half-wavelength plates 4 , 7 , Faraday rotator 8 and polarizing beam splitter 9 , all of which are excluded from the probe unit 15 shown in FIG. 1.
- the present embodiment is characterized by that an optical axis of incoming beams of the electro-optical element 2 differs from an optical axis of outgoing beams of the electro-optical element 2 .
- the collimator lens 10 shown in FIG. 3 is replaced with a converging lens 10 a.
- the converging lens 10 a is arranged at a location, which matches with a point on the reflector 2 a at which the laser beams radiated from the laser diode 11 are to be converged. So, the laser beams are converged (focused) at such a point on the reflector 2 a.
- Reflected laser beams reflected by the reflector 2 a are converted to parallel beams by the collimator lens 3 .
- the parallel beams enter the polarization detector 14 , wherein they pass through the quarter-wavelength plate 5 and are then subjected to separation by the polarizing beam splitter 6 . That is, reflected beams being reflected by the polarizing beam splitter 6 are incident on the photodiode 12 , while transmitting beams that transmit through the polarizing beam splitter 6 are output from the polarization detector 14 and are then incident on the photodiode 13 . Therefore, the photodiode 12 converts the reflected beams to electric signals, while the photodiode 13 converts the transmitting beams to electric signals.
- the optical parts are designed and arranged such that the optical axis of the incoming beams of the electro-optical element 2 differs from the optical axis of the outgoing beams of the electro-optical element 2 which correspond to the reflected beams of the reflector 2 a.
- Such design and arrangement do not require the optical isolator 14 a.
- the polarization detector 14 that is provided for separation of the polarization components is configured by a small number of optical parts. So, it is possible to reduce a total number of optical parts required for construction of the probe unit 15 .
- the present embodiment is capable of reducing a number of optical parts, it is possible to suppress an amount of noise components, which emerge due to reflection at surfaces of the optical parts. In addition, it is possible to reduce a number of points for adjustments of optical axes among the optical parts in the probe unit 15 .
- the present embodiment uses a “single” polarizing beam splitter ( 6 ) for separation of the beams, so that the separated beams are respectively distributed to and are directly received by the two photodiodes 12 , 13 . So, it is possible to eliminate a difference in balance between intensities of incoming beams of the photodiodes 12 , 13 , regardless of an optical loss.
- the probe unit 15 of FIG. 2 differs from the aforementioned probe unit of FIG. 1 in that the collimator lens 3 is replaced with a converging lens 10 b.
- the converging lens 10 b is identical to the converging lens 10 a in focal length.
- the converging lens 10 a is arranged distant from the laser diode 11 by an optical-axis length B 1 , while the converging lens 10 a is also arranged distant from the reflector 2 a of the electro-optical element 2 by an optical-axis length B 2 .
- the converging lens 10 b is arranged distant from the reflector 2 a by the optical-axis length B 1 , while the converging lens 10 b is also arranged distant from the photodiode 13 by the optical-axis length B 2 .
- the aforementioned arrangement sets same focal lengths with respect to both of the lenses 10 a, 10 b.
- the laser diode 11 radiates continuous light.
- the general-purpose measurement devices such as the real-time oscilloscope, sampling oscilloscope and spectrum analyzer instead of the EOS oscilloscope.
- the photodiodes 12 , 13 are connected to the measurement device by way of a dedicated controller or else.
- the optical parts are arranged in the probe unit such that the optical axis of the incoming beams of the electro-optical element differs from the optical axis of the outgoing beams of the electro-optical element. So, it is unnecessary to provide the probe unit with the optical isolator, which is replaced with the polarization detector.
- the polarization detector requires a small number of optical parts as compared with the optical isolator, it is possible to reduce a total number of optical parts constructing the electro-optical probe.
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Abstract
Description
- 1. Field of the Invention
- This invention relates to electro-optical probes used for oscilloscopes that use electro-optical crystals to measure waveforms of signals based on electro-optical effects, and particularly to electro-optical probes used for electro-optic sampling oscilloscopes.
- This application is based on Patent Application No. Hei 10-333309 filed in Japan, the content of which is incorporated herein by reference.
- 2. Description of the Related Art
- In general, the electro-optic sampling oscilloscopes operate as follows:
- Electric fields being caused to occur due to measured signals are connected with electro-optical crystals, on which laser beams are incident. Using polarization states of the laser beams in the electro-optical crystals, it is possible to detect the measured signals. Herein, the laser beams are formed in a pulse-like form, so that it is possible to measure waveforms of the signals with a very high resolution with respect to time. The electro-optic sampling oscilloscopes use electro-optical probes, which work based on the known electro-optical phenomenon.
- As compared with the conventional sampling oscilloscopes using probes of an electric type, the electro-optic sampling oscilloscopes (abbreviated by “EOS” oscilloscopes) draw considerable attention of scientists and engineers because of some advantages, as follows:
- (1) It is easy to perform measurement on the waveforms of the signals because the EOS oscilloscopes do not require ground lines when measuring the signals.
- (2) A metal pin provided at a tip end of the electro-optical probe is insulated from the circuitry, so it is possible to realize high input impedance. Therefore, it is possible to perform measurement without substantially disturbing states of measuring points.
- (3) The EOS oscilloscope uses optical pulses for the measurement. So, it is possible to perform the measurement in a broad band, a frequency range of which is increased up to Giga-Hertz (GHz) order.
- Now, a description will be given with respect to an example of the EOS oscilloscope with reference to FIG. 3. Specifically, FIG. 3 shows a
probe unit 15 of the EOS oscilloscope, which is equipped with a probe head 1 made of an insulator. Ametal pin 1 a is installed at a center of the probe head 1. An electro-optical element (i.e., electro-optical crystal) 2 is equipped with a reflector (or reflection mirror) 2 a, which is formed at a terminal surface facing with an end of themetal pin 1 a and is brought into contact with themetal pin 1 a. Theprobe unit 15 containscollimator lenses 3, 10, half-wavelength (or ½ wavelength)plates 4, 7, a quarter-wavelength (or ¼ wavelength)plate 5, polarizingbeam splitters rotator 8, which rotates a polarizing plane of incident light by 45 degrees. In addition, theprobe unit 15 contains alaser diode 11, which radiates laser beams in response to a control signal output from a main body of the EOS oscilloscope (not shown), as well asphotodiodes probe unit 15 contains anoptical isolator 14 a, which is configured by the half-wavelength plates 4, 7, quarter-wavelength plate 5,beam splitters rotator 8. - Next, an optical path of the laser beams radiated from the
laser diode 11 will be described with reference to FIG. 3, wherein it is denoted by a reference symbol “C”. - The
collimator lens 10 converts the laser beams output from thelaser diode 11 to parallel beams, which propagate straight through the polarizingbeam splitter 9, Faradayrotator 8, half-wavelength plate 7 and polarizingbeam splitter 6 sequentially in a forward direction. They also pass through the quarter-wavelength plate 5 and half-wavelength plate 4 sequentially. Thereafter, the parallel beams are converged together by the collimator lens 3 and are then incident on the electro-optical element 2 as its incoming beams. The incoming beams of the electro-optical element 2 are reflected by thereflector 2 a, which is formed at the terminal surface of the electro-optical element 2 facing with themetal pin 1 a. - Then, reflected beams are converted to parallel beams by the collimator lens3. The parallel beams propagate through the half-wavelength plate 4 and quarter-
wavelength plate 5 in a backward direction. A part of the parallel beams is reflected by the polarizingbeam splitter 6 and is incident on thephotodiode 12. In contrast, the parallel beams that transmit through the polarizingbeam splitter 6 are reflected by the polarizingbeam splitter 9 and are incident on thephotodiode 13. - The quarter-wavelength plate4 is provided to make adjustment such that strength of incoming laser beams of the
photodiode 12 coincides with strength of incoming laser beams of thephotodiode 13. In addition, the half-wavelength plate 4 is provided to adjust a polarizing plane of an incoming beam of the electro-optical element 2. - Next, a description will be given with respect to a series of measuring operations to perform measurement on signals by using the aforementioned probe of the EOS oscilloscope shown in FIG. 3.
- When a human operator brings the
metal pin 1 a in contact with a measuring point (not shown), an electric voltage is applied to themetal pin 1 a to form an electric field. Such an electric field spreads and is connected with the electro-optical element 2. Due to Pockel's effect, there is caused to occur a phenomenon in which a birefringence index changes. Thelaser diode 11 radiates laser beams, which are incident on the electro-optical element 2. Due to the aforementioned phenomenon, the incoming laser beams that propagate in the electro-optical element 2 change in polarization states. Then, the laser beams whose polarization states are changed are reflected by thereflector 2 a and are incident on thephotodiodes photodiodes - Accompanied with changes of the voltage applied to the
metal pin 1 a at the measuring point, changes occur with respect to the polarization states of the beams in the electro-optical element 2. Those changes bring differences between outputs of thephotodiodes metal pin 1 a. - Incidentally, the electric signals produced by the
photodiodes photodiodes - The aforementioned EOS oscilloscope is designed to separate the incoming beams of the electro-
optical element 2, which are brought by theoptical isolator 14 a, from the reflected beams which are reflected by thereflector 2 a. Such a design causes a problem in which a number of optical parts constructing theoptical isolator 14 a is increased. - Due to an increased number of optical parts, “unnecessary” reflected beams are produced by some optical parts. This causes another problem in which an amount of noise component is increased while a S/N ratio in signal processing is reduced. In addition, there is a still another problem in which the incoming beams of the two
photodiodes - It is an object of the invention to provide an electro-optical probe used for an electro-optic sampling oscilloscope, which is equipped with a reduced number of optical parts and which is improved in S/N ratio.
- Basically, an electro-optical probe of this invention is provided for an electro-optic sampling oscilloscope, which is designed as follows:
- Electric fields caused by measured signals are connected with an electro-optical crystal, on which optical pulses produced based on timing signals are incident and in which the optical pulses are changed in polarization states. Thus, the electro-optic sampling oscilloscope is capable of measuring waveforms of the measured signals based on changes of the polarization states.
- Particularly, this invention provides an improvement in an optical system of the electro-optical probe.
- Namely, the electro-optical probe is mainly constructed by a probe head and a probe unit. The probe head contains a metal pin being brought into contact with a measuring point to detect an electric field caused by the measured signal and an electro-optical element having a reflector at its terminal surface facing with an end of the metal pin. The probe unit contains a reduced number of optical parts, which are arranged such that an optical axis of incoming beams of the electro-optical element differs from a optical axis of outgoing beams of the electro-optical element. That is, laser beams radiated from a laser diode propagate along a first optical path and are subjected to convergence by a converging lens to produce converged beams, which are incident on the electro-optical element as its incoming beams. The incoming beams are subjected to reflection by the reflector to produce reflected beams, which are output from the electro-optical element as its outgoing beams along a second optical path. Herein, the first and second optical paths are selected not to be in parallel with each other.
- In the electro-optical element, the beams are changed in polarization states in response to the electric field. Then, the reflected beams output from the electro-optical element are converted to parallel beams by a collimator lens and are then input to a polarization detector. Or, they are converged by a converging lens and are then input to the polarization detector. The polarization detector performs separation on the input beams thereof to produce separated components of beams, optical axes of which differ from each other. Herein, a first component of beams substantially corresponding to the input beams is incident on a first photodiode, while a second component of beams corresponding to a part of the input beams is incident on a second photodiode. Thus, the first and second photodiodes respectively output electric signals.
- Changes of the polarization states of the beams in the electro-optical element are reflected by differences between the electric signals output from the photodiodes. Thus, it is possible to measure the waveform of the measured signal based on the differences between the electric signals.
- Because of the aforementioned arrangement of the optical parts in the probe unit and because of adoption of the polarization detector whose configuration is simple as compared with the conventional optical isolator, it is possible to reduce a total number of the optical parts, while it is possible to improve a S/N ratio in signal processing with respect to measurement of the waveforms of the signals.
- These and other objects, aspects and embodiments of the present invention will be described in more detail with reference to the following drawing figures, of which:
- FIG. 1 is a schematic illustration partially in section showing a construction of an electro-optical probe used for an electro-optic sampling oscilloscope in accordance with embodiment1 of the invention;
- FIG. 2 is a schematic illustration partially in section showing a construction of an electro-optical probe used for the electro-optic sampling oscilloscope in accordance with
embodiment 2 of the invention; and - FIG. 3 is a schematic illustration partially in section showing a construction of an electro-optical probe used for the conventional electro-optic sampling oscilloscope.
- This invention will be described in detail by way of examples in conjunction with the accompanying drawings.
- FIG. 1 shows a configuration of an electro-optical probe of an electro-optic sampling oscilloscope in accordance with embodiment1 of the invention. Specifically, FIG. 1 shows internal configurations of a probe head 1 and a
probe unit 15, wherein parts equivalent to those shown in FIG. 3 are designated by the same reference numerals, hence, the description thereof will be omitted according to needs. - Different from the foregoing
probe unit 15 of FIG. 3 which uses theoptical isolator 14 a, theprobe unit 15 shown in FIG. 1 is configured using apolarization detector 14, which is provided for separation of polarization components. Herein, thepolarization detector 14 is configured by the aforementioned quarter-wavelength plate 5 andpolarizing beam splitter 6 without using the aforementioned half-wavelength plates 4, 7,Faraday rotator 8 andpolarizing beam splitter 9, all of which are excluded from theprobe unit 15 shown in FIG. 1. In addition, the present embodiment is characterized by that an optical axis of incoming beams of the electro-optical element 2 differs from an optical axis of outgoing beams of the electro-optical element 2. Further, thecollimator lens 10 shown in FIG. 3 is replaced with a converginglens 10 a. - Next, optical paths of laser beams radiated from the
laser diode 11 will be described with reference to FIG. 1, wherein each optical path is denoted by a reference symbol “A”. - First, laser beams output from the
laser diode 11 are converged together by the converginglens 10 a and are incident on the electro-optical element 2 as its incoming beams. Then, the incoming beams is reflected by thereflector 2 a, which is formed at the terminal surface of the electro-optical element 2 facing with themetal pin 1 a. - The converging
lens 10 a is arranged at a location, which matches with a point on thereflector 2 a at which the laser beams radiated from thelaser diode 11 are to be converged. So, the laser beams are converged (focused) at such a point on thereflector 2 a. - Reflected laser beams reflected by the
reflector 2 a are converted to parallel beams by the collimator lens 3. The parallel beams enter thepolarization detector 14, wherein they pass through the quarter-wavelength plate 5 and are then subjected to separation by thepolarizing beam splitter 6. That is, reflected beams being reflected by thepolarizing beam splitter 6 are incident on thephotodiode 12, while transmitting beams that transmit through thepolarizing beam splitter 6 are output from thepolarization detector 14 and are then incident on thephotodiode 13. Therefore, thephotodiode 12 converts the reflected beams to electric signals, while thephotodiode 13 converts the transmitting beams to electric signals. - Accompanied with voltage changes at a measuring point, changes are caused to occur in polarization states of the incoming laser beams in the electro-
optical element 2. Such changes bring differences between outputs of thephotodiodes photodiodes metal pin 1 a of the probe head 1. - In the present embodiment, the optical parts are designed and arranged such that the optical axis of the incoming beams of the electro-
optical element 2 differs from the optical axis of the outgoing beams of the electro-optical element 2 which correspond to the reflected beams of thereflector 2 a. Such design and arrangement do not require theoptical isolator 14 a. As compared with the aforementionedoptical isolator 14 a that requires a relatively large number of optical parts, thepolarization detector 14 that is provided for separation of the polarization components is configured by a small number of optical parts. So, it is possible to reduce a total number of optical parts required for construction of theprobe unit 15. - Because the present embodiment is capable of reducing a number of optical parts, it is possible to suppress an amount of noise components, which emerge due to reflection at surfaces of the optical parts. In addition, it is possible to reduce a number of points for adjustments of optical axes among the optical parts in the
probe unit 15. - The present embodiment uses a “single” polarizing beam splitter (6) for separation of the beams, so that the separated beams are respectively distributed to and are directly received by the two
photodiodes photodiodes - Next, a description will be given with respect to an electro-optical probe of an electro-optic sampling oscilloscope in accordance with
embodiment 2 of the invention with reference to FIG. 2. In FIG. 2, parts equivalent to those shown in FIG. 1 are designated by the same reference numerals, hence, the description thereof will be omitted according to needs. - The
probe unit 15 of FIG. 2 differs from the aforementioned probe unit of FIG. 1 in that the collimator lens 3 is replaced with a converginglens 10 b. Herein, the converginglens 10 b is identical to the converginglens 10 a in focal length. The converginglens 10 a is arranged distant from thelaser diode 11 by an optical-axis length B1, while the converginglens 10 a is also arranged distant from thereflector 2 a of the electro-optical element 2 by an optical-axis length B2. In addition, the converginglens 10 b is arranged distant from thereflector 2 a by the optical-axis length B1, while the converginglens 10 b is also arranged distant from thephotodiode 13 by the optical-axis length B2. - The aforementioned arrangement sets same focal lengths with respect to both of the
lenses photodiodes laser diode 11, to light-receiving elements of thephotodiodes - Incidentally, it is possible to modify the aforementioned embodiments such that the
laser diode 11 radiates continuous light. In that case, it is possible to perform signal processing by using the general-purpose measurement devices such as the real-time oscilloscope, sampling oscilloscope and spectrum analyzer instead of the EOS oscilloscope. Herein, thephotodiodes - As described heretofore, this invention has a variety of technical features and effects, which are summarized as follows:
- (1) The optical parts are arranged in the probe unit such that the optical axis of the incoming beams of the electro-optical element differs from the optical axis of the outgoing beams of the electro-optical element. So, it is unnecessary to provide the probe unit with the optical isolator, which is replaced with the polarization detector.
- (2) Because the polarization detector requires a small number of optical parts as compared with the optical isolator, it is possible to reduce a total number of optical parts constructing the electro-optical probe.
- (3) Due to reduction of the number of the optical parts of the electro-optical probe, it is possible to suppress an amount of noise components, which emerge due to reflection of surfaces of the optical parts.
- (4) Only a single polarizing beam splitter is required for separation of beams, which are to be distributed to two photodiodes respectively. So, it is possible to set a same optical length with respect to both of the beams input to the photodiodes. Thus, it is possible to eliminate a difference in balance between intensities of the incoming beams of the two photodiodes.
- As this invention may be embodied in several forms without departing from the spirit of essential characteristics thereof, the present embodiments are therefore illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the claims.
Claims (10)
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
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JP10-333309 | 1998-11-24 | ||
JP33330998 | 1998-11-24 | ||
JP11-275385 | 1999-09-28 | ||
JP11275385A JP2000221213A (en) | 1998-11-24 | 1999-09-28 | Electro-optic probe |
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US20020011830A1 true US20020011830A1 (en) | 2002-01-31 |
US6369562B2 US6369562B2 (en) | 2002-04-09 |
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US09/448,525 Expired - Fee Related US6369562B2 (en) | 1998-11-24 | 1999-11-23 | Electro-optical probe for oscilloscope measuring signal waveform |
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TW594361B (en) * | 2003-04-28 | 2004-06-21 | Univ Nat Taiwan Science Tech | Simultaneous optical isolation and channel monitoring technique for DWDM systems |
CN113418680B (en) * | 2021-06-23 | 2024-01-26 | 青岛大学 | Electro-optic modulation-based thin convex lens focal length measuring device and method |
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JP2527965B2 (en) | 1987-05-31 | 1996-08-28 | 浜松ホトニクス株式会社 | Voltage detector |
JPS63308572A (en) | 1987-06-10 | 1988-12-15 | Hamamatsu Photonics Kk | Voltage detector |
EP0299432B1 (en) * | 1987-07-13 | 1994-06-08 | Hamamatsu Photonics K.K. | A voltage detecting device |
WO1989009413A1 (en) | 1988-03-25 | 1989-10-05 | Princeton Applied Research Corporation | Electro-optic probe |
FR2661003B2 (en) | 1989-12-26 | 1992-06-12 | Commissariat Energie Atomique | ELECTRIC FIELD SENSOR WITH POCKELS EFFECT. |
EP0541139B1 (en) * | 1991-08-05 | 2003-01-22 | Koninklijke Philips Electronics N.V. | Electro-optic measurement device for the measurement of an electrical signal in an electronic component |
JPH0798329A (en) | 1993-09-28 | 1995-04-11 | Hamamatsu Photonics Kk | E-o probe |
JP3003974B2 (en) * | 1993-11-22 | 2000-01-31 | 富士通株式会社 | Voltage / displacement detection probe and voltage / displacement measuring device using the same |
-
1999
- 1999-09-28 JP JP11275385A patent/JP2000221213A/en active Pending
- 1999-11-23 US US09/448,525 patent/US6369562B2/en not_active Expired - Fee Related
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10802066B1 (en) * | 2019-12-17 | 2020-10-13 | Quantum Valley Ideas Laboratories | Single-pixel imaging of electromagnetic fields |
Also Published As
Publication number | Publication date |
---|---|
JP2000221213A (en) | 2000-08-11 |
US6369562B2 (en) | 2002-04-09 |
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