Other

Ando Electric Company

Nobukazu Banjo

Mitsuru Shinagawa

Tadao Nagatsuma

Jun Kikuchi

Yoshiki Yanagisawa

Junzo Yamada

Nobuaki Takeuchi

Yoshio Endou

Hakaru Kyuragi

Akishige Ito

Sanjay Gupta

An electro-optic probe has a laser diode for emitting a laser beam in accordance with a control signal from a measuring instrument main body, an electro-optic or magneto-optic element provided with a reflection film on an end surface thereof, a separator provided between the laser diode and electro-optic or magneto-optic element which is pervious the laser beam emitted from the laser diode and separates a beam reflected from the reflection film and two photodiodes which transform the beam reflected by the separator. A member of weak dielectric material, such as a glass plate, overlies the electro-optic or magneto-optic element at the end of the probe to protect the element, or the element is at the end of the probe and is exposed.

Electro-optic probe and magneto-optic probe

An electro-optic sampling oscilloscope (or EOS oscilloscope) uses an electro-optic probe containing an electro-optic crystal, which is placed under effect of an electric field caused by a measured signal. Laser pulses are supplied to the electro-optic crystal wherein they are subjected to polarization. Then, measurement data representative of a waveform of the measured signal are produced in response to polarization states of the laser pulses and are stored in a measurement data storage. A user can select specific measurement data by using a list of files of multiple measurement data which is displayed on a screen. Then, the EOS oscilloscope displays an outline waveform which is created based on a reduced number of sample points extracted from the selected measurement data. Comments and/or measurement conditions can be stored in the measurement data storage in relation to the measurement data, so that they are adequately displayed on the screen.

Electro-optic sampling oscilloscope

In a light receiving circuit for use in electro-optic sampling oscilloscope which receives first and second optical, photodiodes and are connected in series between a positive bias power supply P and a negative bias power supply N. The photodiodes and receive optical signals whose polarization state correspond to the voltage of a signal to be measured and convert the thus-received optical signals into electric signals. An amplifier amplifies an electric current appearing in a point of connection P between the photodiodes and A current monitor detects the electric signal converted by the photodiode and a current monitor detects the electric signal converted by the photodiode The electric signal detected by the current monitor is subjected to analog-to-digital conversion by an analog-to-digital converter and the electric signal detected by the current monitor is subjected to analog-to-digital conversion by an analog-to-digital converter A control section formed from a subtraction circuit controls a ratio of polarization between the optical signals such that the difference between the value of the current detected by the current monitor and the value of the current detected by the current monitor becomes smaller.

Light receiving circuit for use in electro-optic sampling oscilloscope

An electro-optic sampling oscilloscope (or EOS oscilloscope) is designed to perform measurement such that an electro-optic sampling probe (i.e., EOS probe) is brought into contact with a measured circuit. Optical pulses are input to the EOS probe, wherein they are varied in polarization states in response to the measured circuit. Then, an electric signal output from the EOS probe is amplified to produce a receiving light signal. The receiving light signal is subjected to sampling operations using a first pulse signal to produce detection data, while it is also subjected to sampling operations using a second pulse signal to produce noise data. Herein, the first pulse signal consists of pulses which emerge in synchronization with the optical pulses respectively, while the second pulse signal delays from the first pulse signal by a prescribed delay time. Then, measurement data are produced by subtracting the noise data from the detection data. The measurement data are processed so that a measured waveform representing a measurement result is displayed on a screen of the EOS oscilloscope. Thus, it is possible to obtain the measured waveform with high precision and a good S/N ratio by eliminating low-frequency noise components from the measurement results.

Electro-optical oscilloscope with improved sampling

An electro-optic sampling oscilloscope facilitates adjustment of signal-to-noise ratio caused by electrical, optical and temperature factors. The instrument includes: a light generation section for generation a reference laser beam; a crystal, exhibiting an electro-optic response behavior so as to receive the reference laser beam and to result in changing a refractive index in accordance with electrical field strength generated by target signal; a reflection mirror formed on a rear surface of the crystal for reflecting the reference laser beam that has passed through the crystal; an optical circuit for separating the reference laser beam reflected from the reflection mirror into a first signal light and a second signal light; a first photo-electric conversion section for converting the first signal light into first electrical signals; a second photo-electric conversion section for converting the second signal light into second electrical signals; a differential amplification section for differentially amplifying the first electrical signals and the second electrical signals, and for outputting differentially amplified signals as detection signals of the target signal; and a gain adjustment section for varying gains to adjust a signal-to-noise ratio while the reference laser beam is not being radiated into the crystal, so as to match strength levels of the first electrical signals and the second electrical signals in association with feedback signals of the target signal.

A measurement system analyzes and displays measurement data obtained from measurement modules with respect to prescribed measured values. A large scale graphical user interface (GUI) is provided as a human-machine interface and functions as a display as well as a data input device. The measurement system employs double CPU modules for sharing loads of data processing required for the GUI and measurement modules, respectively. A first CPU module controls the human-machine interface and performs data processing. A second CPU module controls the measurement modules. The first CPU module uses a firsts system for communications, whereas the second CPU module uses a second bus system for communications with the measurement modules. A bus exchanger connects the first and second bus systems so that a user of the system can control the measurement system using the GUI while providing real-time performance for the measurement modules.

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Tokyo, Japan

Nobukazu Banjo