Abstract: A particle detector which can detect smaller particles by increasing the pulse width of the particle signal output from a photoelectric transducer element, includes a particle monitoring region formed by irradiating sample fluid with laser light, and light scattered from particles passing through the particle monitoring region is received by a photoelectric transducer element so as to detect a particle. The direction of flow of the sample fluid and the direction of the laser light are arranged parallel to each other. The particle detector may have a condenser lens for condensing the scattered light and a slit provided at a focal point of the condenser lens and extending in a direction parallel to the sample fluid flow. Also, the particle detector may have a condenser circuit for integrating the output signal of the photoelectric transducer element, and a low-pass filter for filtering the output signal of the condenser circuit.

Abstract: A particle counter for measuring the number of floating particles contained in a sample to determine the particle concentration therein includes: a memory section for storing a relational expression between the direct current level output from a photoelectric converter when no particles exist and the frequency of occurrence of false counts; and a subtraction section for determining the frequency of occurrence of the false counts corresponding to the direct current level output from the photoelectric converter at the time of commencement of measurement with reference to the relational expression stored in the memory section and subtracting a value based on the frequency of occurrence of the false counts from a discrete value after commencement of measurement.

Abstract: A flow cell is provided which can detect scattered light more efficiently by fully utilizing the condensing angle of a condenser lens. A particle monitoring area M is formed within the flow cell by irradiating the area with laser light La, and scattered light Ls generated by particles contained in sample fluid passing through the particle monitoring area M is condensed by the condenser lens L so as to obtain information including diameter of the particles, and inner walls of the flow cell are shaped or arranged such that the scattered light Ls is condensed in a state where the condensing angle ? of the condenser lens L is fully utilized.

Abstract: A flow cell is provided which can detect scattered light more efficiently by fully utilizing the condensing angle of a condenser lens. A particle monitoring area M is formed within the flow cell by irradiating the area with laser light La, and scattered light Ls generated by particles contained in sample fluid passing through the particle monitoring area M is condensed by the condenser lens L so as to obtain information including diameter of the particles, and inner walls of the flow cell are shaped or arranged such that the scattered light Ls is condensed in a state where the condensing angle ? of the condenser lens L is fully utilized.

Abstract: According to the present invention, there is provided a light scattering type particle detector, using a semiconductor laser as a light source, for detecting particles contained in sample fluid which defines a flow path, wherein laser light generated from the semiconductor laser is irradiated to irradiate a region of the flow path with a concave mirror and thereby a particle detecting region is defined. According to the present invention, there is also provided a laser oscillator wherein the optical axis of a semiconductor laser for generating pumping laser light has a predetermined angle with respect to the optical axis of a laser medium for irradiating laser light by pumping. Using such a laser oscillator, laser light irradiated from the laser oscillator is condensed to irradiate a region of a flow path defined by sample fluid, and thereby a particle detecting region is defined. Particles contained in the particle detecting region are detected by receiving scattered light with a light receiving portion.

Abstract: A particle detector comprising an optical cavity constructed of a solid-state laser which is optically pumped by pumping light generated from a pumping light source and a reflecting mirror, the optical cavity generating laser light, a flow path defined by sample fluid, and a particle detecting region where the laser light La is radiated upon the flow path, wherein particles passing through the particle detecting region are detected by receiving light scattered from the laser light due to the particles passing through the particle detecting region, and wherein the laser light generated within the optical cavity has a multi transverse mode, the cross sectional shape of which has a different length in the longitudinal direction and the transverse direction.

Abstract: According to the present invention, there is provided a light scattering type particle detector, using a semiconductor laser as a light source, for detecting particles contained in sample fluid which defines a flow path, wherein laser light generated from the semiconductor laser is irradiated to irradiate a region of the flow path with a concave mirror and thereby a particle detecting region is defined.

Abstract: There is provided a particle detector comprising an optical cavity constructed of a solid-state laser which is optically pumped by pumping light generated from a pumping light source and a reflecting mirror, the optical cavity generating laser light, a flow path defined by sample fluid, and a particle detecting region where the laser light La is radiated upon the flow path, wherein particles passing through the particle detecting region are detected by receiving light scattered from the laser light due to the particles passing through the particle detecting region, and wherein the laser light generated within the optical cavity has a multi transverse mode, the cross section shape of which has a different length in the longitudinal direction and the transverse direction.

Abstract: A flow cell for obtaining information on particles suspended in sample fluid, wherein an irradiation region M is defined in the flow cell for functioning as a particle detection portion to be irradiated with a laser beam La, and a wall portion of the flow cell is so adapted and arranged that the laser beam La becomes incident upon an outer wall surface of the flow cell 1 at a predetermined angle &thgr;1 (&thgr;1≠0°) and exits from an inner wall surface 5b of the flow cell 1 into the sample fluid 6 at a refraction angle 0°. Further the wall portion 5 of the flow cell 1 is so arranged that the laser beam La becomes incident upon a boundary surface between the sample fluid and the opposite inner wall surface of the flow cell 1 at a predetermined incident angle &agr; (&agr;≠0°) after being incident upon the sample fluid and passing through the irradiation region M.