Ando Electric Company

Other

Yokogawa Electric Corporation

Nippon Telegraph and Telephone Corporation

Oki Electric Industry Co., Ltd.

Yokogawa Test & Measurement Corporation

Tohru Mori

Gentaro Ishihara

Tsutomu Kaneko

Kazumasa Takada

Kazuo Aida

Takashi Iwasaki

Masaru Fukushima

Shoichi Aoki

Yoshinori Koshida

Fumio Akikuni

Manabu Kojima

Tetsuo Yano

Seiji Funakawa

Toshikazu Yamamoto

Masafumi Koga

Shusaku Tanabe

Atsushi Horiguchi

Seiji Yoshizawa

Masaharu Horiguchi

Satoshi Hamasaki

Sinichi Suto

A measurement device is provided. The measurement device includes a display, a detector, an operation unit, and a central processing unit. The detector detects a physical quantity and outputs measurement data based on the detected physical quantity. The operation unit includes plural keys for performing operation functions for operating the measurement device to detect and output the measurement data. The central processing unit controls the display to display the measurement data on the display, and to lock the operation unit such that all of the operation functions are temporarily inoperable except for an unlocking function and one or more of the operation functions that is set to be selectively operable even when the operation unit is locked.

Electronic device

A measurement device is provided for measuring a predetermined physical quantity which is contained in the measurement signal over a predetermined measurement range which relates to a specific property for the physical quantity according to the measurement signal which is obtained from an object for measurement so as to display the measurement result as an image in a measurement display which comprises a display range setting section which sets the measurement range, a measurement display generating section which generates the measurement display by using the measurement result in a display range which is set by the measurement range setting section among the measurement result which is measured over the measurement range which is set by the measurement range setting section, and a display section which displays the measurement display which is generated by the measurement display generating section. By doing this, it is possible to enhance an operability of the measurement device by varying the display range of the measurement result freely without changing the measurement scale.

Measurement device and method for displaying measurement result

A photodetector continuously measure quantity of light ranging from high intensity to low intensity at high speed. The photodetector comprises an operational amplifier, a photodiode connected to an inverting terminal of the operational amplifier for outputting a signal corresponding to quantity of light to be detected, a plurality of feedback resistors differentiated in each resistance value, an analog switch for selectively connecting input terminals thereof to which one ends of the feedback resistors are connected to an output terminal of the operational amplifier except the feedback resistor having the maximum resistance value, or connecting the input terminal thereof which is rendered in a non-connection state to the output terminal of the operational amplifier instead of the feedback resistor having the maximum resistance value, wherein the feedback resistor having the maximum resistance value is connected to the output terminal of the operational amplifier at its one end and to the inverting input terminal of the operational amplifier at its other end, and wherein the other ends of the other feedback resistors are connected to the inverting input terminal of the operational amplifier.

Photodetector with plural switched feedback resistors

Output light spectrum P(&#x3bb;) data from an optical amplifier and input light spectrum P(&#x3bb;) data of signal light are prepared, the difference between the P(&#x3bb;) and a value obtained by multiplying the P(&#x3bb;) by a provisional gain GT is determined (Steps S), for the obtained spectrum data, a noise removing process such as a moving average process and the like is performed and then, a spline interpolation process is also performed, whereby ASE light spectrum P(&#x3bb;) data is prepared and an ASE light level P ASE is determined (Steps Sthrough S). In addition, a noise figure-measuring devicecalculates the number of channels of WDM light and signal light wavelengths of the respective channels based on the P(&#x3bb;) or P(&#x3bb;), and performs analysis to calculate a noise figure NF and the like of an appointed wavelength range around the center of each wavelength thus calculated.

Noise figure-measuring device and noise figure-measuring method

A monochromator including: a concave mirror which converts incident light into parallel light and emits the parallel light, a plane diffraction grating for diffracting the parallel light emitted from the concave mirror, first reflection means which reflects first light diffracted by the plane diffraction grating and causes the diffracted light to enter the plane diffraction grating as second incident light, second reflection means which reflects second diffracted light and causes the reflected light to enter the plane diffraction grating as third incident light, and an exit slit disposed in the vicinity of a focal point such that third diffracted light is reflected by the first reflection means, to thereby enter the plane diffraction grating as fourth incident light and such that fourth diffracted light is converged at the focal point by the concave mirror, to thereby enable extraction of light having a specific wavelength.

Monochromator and optical spectrum analyzer using the same

A photocoupler splits the light from a low-coherence light source into measuring light DL and local oscillator light KL. A photocoupler receives measuring light DL arid is input to an optical circuit to be measured. The photocoupler splits the reflected light RL. A polarization controller controls the state of polarization of the reflected light RL as split by the photocoupler . A photocoupler allows local oscillator light KL to be incident on a reflector mirror and splits local oscillator light KL. A photocoupler combines the reflected light RL as controlled in the state of polarization by the polarization controller , with the local oscillator light KL.

Low-coherence reflectometer with polarization control

An optical spectrum analyzer and a wavelength variable light source have each a sweep synchronization start function. A correction function of the rotation speed of a motor for varying the angle of a diffraction grating in a spectroscope so that extracted wavelength and output signal light wavelength match over a setup sweep wavelength range is found from the output signal light wavelength characteristic relative to the rotation angle of a spectral element and the extracted wavelength of the spectroscope , and the rotation angle of motor for driving the spectroscope is varied for each setup wavelength in accordance with the correction function, then sweep is performed.

Wavelength characteristic measurement apparatus

In order to start sweeping an optical spectrum analyzer and a wavelength tunable light source on the same timing, a motor for driving a spectroscope in the optical spectrum analyzer is controlled. To this end, a drive circuit outputs a control signal to determine the timing where the motor starts to rotate. A wavelength control circuit in the wavelength tunable light source controls the sweep of the wavelength of single-mode oscillation from a light source unit and starts sweeping the light source unit in response to a signal externally supplied to control the timing of sweep start. As a result, the sweep of the wavelength being measured with the optical spectrum analyzer and that of the wavelength of single-mode oscillation from the wavelength tunable light source are started on the same timing and high-speed sweep is achieved.

Wavelength tracking system using an optical spectrum analyzer and a wavelength tunable light source

In an optical amplifier evaluation instrument, a rectangular spectrum light source transmits continuous light having a wide-band and flat spectrum shape, a first optical modulator receives and pulse-modulates the continuous light. Further, a second optical modulator operates in the same period as the first optical modulator and performs the on/off pulse operation, thereby providing a sampling window in a time domain for extracting and suppressing an optical signal. A modulation signal generation section performs such control and drive. An optical signal undergoing pulse intensity modulation is input to a measured optical amplifier Post-amplified signal light power for each frequency component and amplified spontaneous emission power for each frequency component in a time domain in which no optical pulse signal exists are measured and operations are performed for each wavelength.

Optical amplifier evaluation method and optical amplifier evaluation instrument

Emitted light from a light source is separated into two parts through an optical fiber coupler , one is entered in a measured optical module as measurement light, and the other is given a group delay by means of an optical fiber delay line , a reflector , etc., as local light signal, then the local light signal is combined with reflected light signal from the measured optical module through an optical fiber coupler and the reflected light signal and the local light signal are caused to interfere with each other. A polarization controller comprising a polarizer and a polarization rotation device for arbitrarily rotating the polarization state 0 degrees and 90 degrees at the time is used to generate beat signals at the polarization rotation angles, and the sum of the intensities of the beat signals is found, making it possible to measure the light power of the reflected light signal regardless of the polarization state of the local light signal or reflected light signal.

Polarization-independent reflectometry and polarization-independent reflectometer

The present invention relates to a double pass monochromator that improves wavelength resolution and reduces the actual length thereof. A return reflection means 7 that reverses the direction of dispersion of the wavelength of the second pass light 1c, 1f emitted and incident on a diffraction grating 4 during the reflection. In addition, the angles of the incident and emitted light during separation of spectral components by the diffraction grating are identical during the first and second diffraction.

Double pass monochromator

An optoacoustic modulator contains first and second optoacoustic media, to which first and second piezoelectric vibrators are attached respectively. Herein, both of the first and second optoacoustic media are designed in same measurements, wherein they are arranged in series along an optical axis of a light signal in such a way that crystal orientation of the first optoacoustic media differs from crystal orientation of the second optoacoustic media with an angle of inclination of 90.degree.. In addition, the first piezoelectric vibrator is attached to a first surface of the first optoacoustic media which is placed in parallel with the optical axis of the light signal, while the second piezoelectric vibrator is attached to a second surface of the second optoacoustic media which is placed in parallel with the optical axis of the light signal, wherein the first surface is directed perpendicular to the second surface. The light signal, corresponding to incoming light incident on the optoacoustic modulator, is input to the first optoacoustic media. Then, the light signal transmitted through the first optoacoustic media is input to the second optoacoustic media, from which a desired output corresponding to outgoing light is output. The first and second piezoelectric vibrators are controlled by modulation signals, which are independently adjusted to cancel polarization mode dispersions of the optoacoustic media. In addition, it is possible to improve ripple characteristic of loss-wavelength dependency characteristic of the optoacoustic media, while it is possible to reduce an amount of crosstalk that occurs at a high-speed modulation mode.

Optoacoustic modulator

A distance correction method and the controller for a reflectometer is disclosed which is able to perform accurate correction of the distances measured by reflectometer. In the distance correction method for the reflectometer which measures the Fresnel reflection or Raleigh back-scattering light of an optical fiber or an optical waveguide, the distance correction D.sub.wg1 -D.sub.wgn is performed according to the respective group refraction ratios which are the parameters of the optical fiber or the optical waveguides longitudinally connected with having different known group refraction ratios.

Distance correction method and the controller for the reflectometer

An optical amplifier evaluating device has a wavelength multiplex signal light generating section, and an O/E converter, and a frequency discriminating and power detecting device, and a computing section. The wavelength multiplex signal light generating section generates an wavelength multiplex signal light which includes signal lights having different wavelengths and having intensity envelopes modulated by different modulation frequencies which are enough higher than an atom life time in a high energy level or a carrier life time in an amplification medium of an optical amplifier to be evaluated, and supplies the wavelength multiplex signal light to the optical amplifier. The O/E converter converts an output light of the optical amplifier to an electric signal. The frequency discriminating and power detecting section detects signal powers of frequency spectrums which are included in the electric signal and respectively correspond to the modulation frequencies of the signal lights, and detects a noise power of the electric signal at a frequency band which is apart from the modulation frequencies. The computing section determines gains and noise figures of the wavelength multiplex amplification by the optical amplifier based on the signal powers and the noise power wavelength by wavelength.

Growing community of inventors

Tokyo, Japan

Tohru Mori