Abstract: A sample flow, including a plurality of components which have different types of spectra and are subjected to flocculation, is irradiated with a light of beam including two or more wavelengths. The transmitted light beam is received by a photoelectric converting device, and electric signals corresponding to respective wavelengths of the transmitted light beam are obtained. The correlation coefficient between the electric signal is calculated, from which the flocculation process of the sample flow with regard to the elapsed time can be easily and quickly detected.

Abstract: A particle detecting device for detecting particles contained in a flowing sample fluid is provided which comprises a light beam irradiating mechanism for irradiating the sample fluid with a light beam, the light beam irradiating mechanism including a light beam deflecting portion for directing the light beam across the flow of the sample fluid and for causing the light beam to scan a predetermined irradiation region of the sample fluid, this scanning causing a portion of the light beam to be scattered by the particles in the irradiation region to produce scattered light; a light receiving mechanism for receiving the scattered light and for converting the scattered light to an electrical signal; and a signal processor coupled to the light receiving mechanism for processing the electric signal to obtain at least one of the number of particles in the sample fluid and a particle size distribution for the particles in the sample fluid.