National Institute of Advanced Industrial Science and Technology

Naoko Oouchi

Haruhisa Kato

Ayako Nakamura

To provide a particle size measuring device that enables simple in-line measurement of the particle size even in a case of nano-sized particles during dispersion. Provided is a particle size measuring device which measures the particle size of particles that perform Brownian motion in a dispersion medium. The particle size measuring device includes a transparent column which accommodates a dispersion medium therein; a laser light irradiating unit which irradiates the dispersion medium in the column with laser light; an imaging unit which includes a camera that images the dispersion medium in the column; an image analyzing unit which acquires a displacement of corresponding particles from at least a plurality of images captured at a predetermined time interval &#x394;t; and a calculating unit which calculates the particle size based on the fact that a root mean square value of the displacement is proportional to kT/3&#x3c0;&#x3b7;d where krepresents a Boltzmann constant, T represents an absolute temperature, &#x3b7; represents a viscosity coefficient of the dispersion medium, and d represents the particle size.

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Tsukuba, Japan

Naoko Oouchi