Patent ID: 7911610

Claim:
An optical measuring device comprising: a container that stores a sample of particles movably dispersed within a medium; an electric power supply that generates a voltage in a predetermined pattern including a DC, a frequency modulation, and a voltage modulation or in a pattern arbitrarily set; an electrode pair that is provided within said container, and generates an electric field distribution regularly arranged within said container upon impression of the voltage by said electric power supply; control means that control the impression of the voltage upon said electrode pair from said electric power supply to generate or extinguish diffraction grating formed by a density modulation of the particles generated by a phoretic force acting upon the particles within the sample within said container; a light source that emits a light beam upon a generated region of said diffraction grating formed within said container; and a photodetector that detects a diffracted light beam of said emitted light beam diffracted by said diffraction grating, wherein: the particles within the sample are evaluated based upon a temporal change of an intensity of the diffracted light beam detected by said photodetector; respective electrodes constituting said electrode pair comprise a comb-like electrode teeth that are parallel with each other, and a connecting portion that electrically connects said respective electrode teeth with each other; and said respective electrodes are arranged such that while said electrode teeth of one of said respective electrodes are inserted between said electrode teeth of the other of said respective electrodes, said electrode teeth of said respective electrodes are separated by a constant interval, are parallel with each other, and are disposed alternately.