Abstract: The object of the present invention is to provide a particle counter which can accurately count the number of particles contained in fluid where the number concentration of particles is high. The particle counter includes a particle removing portion for removing particles contained in fluid at a predetermined rate, a sensor portion for counting the particles passing through the particle removing portion, and a particle number correcting means comprising a characteristic data memory and a digital signal processor for performing correction processing to the number of the particles counted in the sensor portion by using removal characteristics of the particle removing portion with respect to the particle diameter.

Abstract: A method and a system for automatically calibrating a sound level meter which achieves accurate and secure calibration of a sound level meter using a sound calibrator. The sound calibrator comprises a code signal generator and a calibration sound pressure generator. The sound level meter comprises a code signal discriminator, a mode switch for switching the mode into a calibration mode in response to the discrimination of the code signal discriminator, a gain adjuster for adjusting a gain of an amplifier such that the indicated value corresponds to the level of the calibration sound pressure in the calibration mode, and a calibration recorder for recording the calibration date and time, the sound pressure, the type, and the manufacturing number of the sound calibrator.

Abstract: A method and a system for automatically calibrating a sound level meter which achieves accurate and secure calibration of a sound level meter using a sound calibrator. The sound calibrator comprises a code signal generator and a calibration sound pressure generator. The sound level meter comprises a code signal discriminator, a mode switch for switching the mode into a calibration mode in response to the discrimination of the code signal discriminator, a gain adjuster for adjusting a gain of an amplifier such that the indicated value corresponds to the level of the calibration sound pressure in the calibration mode, and a calibration recorder for recording the calibration date and time, the sound pressure, the type, and the manufacturing number of the sound calibrator.

Abstract: A light scattering type particle detector includes a light having a low-energy intensity emitted from a light sources which is converted into light having a high-energy intensity so as to detect fine particles. In the light scattering type particle detector, particles contained in fluid are irradiated with light Lb, and scattered light Ls generated by the particles is received so as to detect the presence of the particles. The light Lb is obtained by converting light La having a wavelength of ? emitted from a light-emitting diode into light having a wavelength of ?/2 after being transmitted through a nonlinear optical crystal. The light Lb having a wavelength of ?/2 is allowed to reciprocate between a reflecting film of the nonlinear optical crystal and a reflecting mirror so as to be intensified.

Abstract: A light scattering type particle detector in which the S/N ratio is improved includes a particle detecting region D which is formed by irradiating laser light La on sample fluid and a light receiving array 5 which receives scattering light Ls due to particles which pass through the particle detecting region. The light receiving array 5 is formed to be circular by arranging a plurality of photoelectric converters Pd1-Pdn in a plane alignment. The particle detector also includes an adder 6 which adds the output from the plurality of the photoelectric converters Pd1-Pdn.

Abstract: According to the present invention, there is provided a light scattering type particle detector in which the S/N ratio is improved. In the light scattering type particle detector, a particle detecting region D is formed by irradiating laser light La on sample fluid and scattering light Ls due to particles which pass through the particle detecting region D is received with the light receiving array 5. The light receiving array 5 is formed to be circular by arranging a plurality of photoelectric converters Pd1-Pdn in a plane alignment. The adder 6 adds the output from the plurality of the photoelectric converters Pd1-Pdn.