Abstract: A particle-containing fluid in a sample cuvette is irradiated by a laser beam from a light source section. The scattered light thus produced passes through converging lenses and a mask and impinges on an etalon interferometer. The etalon only transmits scattered light (Rayleigh scattered light) that is of the same wavelength as the light emitted by the laser light source. The transmitted scattered light components impinges on a photomultiplier, and based on the intensity of the light a calculating section sorts the particles according to size and calculates the number of particles per unit flow amount, the particle size distribution and so forth. To enable adjustments to be made to compensate for the environmental dependency characteristics of the etalon, a control unit is provided which consists of a photodiode and mirrors.

Abstract: A blood flow measurement system for measuring blood flow rate and blood flow velocity comprises a circuit device for irradiating an in vivo tissue measurement subject with coherent light, a light receiving element for receiving scattered light from the in vivo tissue, a converter for converting an intensity of the received scattered light into an electric signal, a circuit device for calculating a power spectrum of the time-course variation of the scattered light intensity, a device for plotting the power spectrum in a semilogarithmic coordinate system having a logarithmic vertical axis, and a device for linearly approximating a prescribed frequency component of the semilogarithmic power spectrum and calculating a slope and a y intercept of the power spectrum curve. The blood flow velocity can be determined from the slope of the curve approximating the power spectrum, while blood flow rate can be determined from the slope and y intercept of the curve approximating the power spectrum.

Abstract: An apparatus for non-invasively measuring the oxygen saturation in the blood of a subject comprises light sources for irradiating a sample of blood in tissue with at least a first light beam and a second light beam having different wavelengths. A switching device drives the light sources and sequentially switches the irradiation of the sample of blood between the first and second laser beams. A photoelectric detector detects light transmitted through or reflected from the sample of blood and provides an electrical output signal indicative of the intensity of the detected light. A converter converts the electrical output signal of the photoelectric detecting device to a power spectrum, and a processor processes the power spectrum and calculates the oxygen saturation of the sample of blood.