Patent ID: 8274654

Claim:
An apparatus for measuring nanoparticles comprising: a cell for storing therein a sample having particles dispersed movably in a medium; a power source for generating an AC or DC voltage; a pair of electrodes formed inside the cell in such a manner as to approximately face each other and to which a voltage is applied from the power source; a dielectric sheet arranged between the pair of electrodes and adapted to form a spatially periodic electric field in the cell with the application of the voltage between the electrodes; an irradiation optical system for applying a parallel light flux into the cell; a detection optical system for detecting diffracted light generated by the parallel light flux transmitting through the cell; control means for controlling the application of the voltage from the power source to the pair of electrodes; and data processing means for calculating the diffusion coefficient and/or size of the particles in the cell from the temporal change of the diffracted light through the application of the voltage and the stopping or modulation of the application.