Abstract: Measurement of Brillouin scattered light is enabled without an optical receiver having a wide reception band.

Abstract: There is provided a distortion measuring device including a Brillouin scattered light spectrum recording unit which records a spectrum of Brillouin scattered light generated in an optical fiber as a result of supplying incident light, a peak frequency approximating unit which acquires an approximated peak frequency at which the recorded spectrum takes a maximal value, a peak frequency deriving unit which derives a peak frequency at which the spectrum takes the maximal value within a range of a frequency determined based on a magnitude of the spectrum at the approximated peak frequency, amid a distortion deriving unit which derives distortion of the optical fiber based on the derived peak frequency.

Abstract: A distortion of a device under test (such as an optical fiber) can be precisely measured. There is provided a distortion measuring device including a signal processing unit 32 having a Brillouin scattered light spectrum recording unit 322a which records a spectrum of Brillouin scattered light generated in an optical fiber as a result of supplying incident light, a Rayleigh scattered light spectrum recording unit 322b which records a spectrum of Rayleigh scattered light generated in the optical fiber as a result of supplying the incident light, a deconvolution unit 324 which derives a Brillouin gain spectrum of the optical fiber based on the recorded spectrum of the Brillouin scattered light and the recorded spectrum of the incident light, a peak frequency deriving unit 326 which derives a peak frequency at which the derived Brillouin gain spectrum takes the maximum value, and a distortion deriving unit 328 which derives a distortion of the optical fiber based on the derived peak frequency.

Abstract: There is provided a distortion measuring device including a Brillouin scattered light spectrum recording unit which records a spectrum of Brillouin scattered light generated in an optical fiber as a result of supplying incident light, a peak frequency approximating unit which acquires an approximated peak frequency at which the recorded spectrum takes a maximal value, a peak frequency deriving unit which derives a peak frequency at which the spectrum takes the maximal value within a range of a frequency determined based on a magnitude of the spectrum at the approximated peak frequency, amid a distortion deriving unit which derives distortion of the optical fiber based on the derived peak frequency

Abstract: A wavelength dispersion probing system for determining a value of wavelength dispersion and its sign and reducing the trouble and time required for this determination. This wavelength dispersion probing system comprises light sources 10, 12, light attenuators 14, 16, optical multiplexer 18, phase modulator 20, optical amplifiers 22, 26, acoustooptical modulator 24, optical receiver 30. The intensity ratio of two wavelengths is set at 1 to 2 to detect Stokes light or anti-Stokes light included in the return light of an optical fiber 100 by the optical receiver 30, so that wavelength dispersion is probed. The wavelength dispersion is probed by changing the intensity ratio of the two wavelengths to observe the state of the change of the wavelength dispersion, so that the sign of wavelength dispersion is determined by the optical receiver 30.

Abstract: A wavelength dispersion probing system for determining a value of wavelength dispersion and its sign and reducing the trouble and time required for this determination. This wavelength dispersion probing system comprises light sources 10, 12, light attenuators 14, 16, optical multiplexer 18, phase modulator 20, optical amplifiers 22, 26, acoustooptical modulator 24, optical receiver 30. The intensity ratio of two wavelengths is set at 1 to 2 to detect Stalk light or anti-Stalk light included in the return light of an optical fiber 100 by the optical receiver 30, so that wavelength dispersion is probed. The wavelength dispersion is probed by changing the intensity ratio of the two wavelengths to observe the state of the change of the wavelength dispersion, so that the sign of wavelength dispersion is determined by the optical receiver 30.

Abstract: A PLL (phase lock loop) circuit improves pull-in and noise performances by changing a loop gain based on the loop states. The PLL circuit includes a voltage controlled oscillator (VCO) for generating an oscillation signal whose oscillation frequency is controlled by a control voltage provided thereto, a phase comparator for detecting a phase difference between the oscillation signal from the VCO and a reference signal wherein a detection gain of the phase difference is regulated by a bias voltage provided thereto, a low pass filter for receiving an output signal of the phase comparator for removing high frequency components therefrom to produce the control voltage supplied to the VCO, a phase lock loop formed by the VCO, phase comparator and low pass filter, and a phase lock detection circuit for detecting whether the phase lock loop has reached a phase lock state and changing the bias voltage to decrease the detection gain of the phase comparator when the phase lock loop has reached the lock state.

Abstract: In a resinoid wheel containing abrasive grains, a binder resin and a filler, an improvement which is characterized in that based on weight 1/3 to 2/3 of the amount of the filler is a mixture of 20 to 55 wt.% of trimanganese tetroxide and 80 to 45 wt.% of e ferric oxide.