Measurement device and measurement method

A measurement device that performs a dynamic light scattering measurement process to characterize particles suspended in a sample medium, the measurement device comprising:

• an optical splitter section that splits light emitted from a low-coherence light source into two beams;
• an illumination section that applies one of the two beams split by the optical splitter section to the sample medium;
• a phase modulation section that modulates the other of the two beams split by the optical splitter section in phase;
• a spectrum acquisition section that resolves the beam subjected to the phase modulation and a scattered beam from the sample medium on a wavelength basis, and acquires a spectrum of interference light of the beam subjected to the phase modulation and the scattered beam;
• and
• a measurement section that performs the dynamic light scattering measurement process to characterize the particles on the basis of the acquired spectrum,
• the measurement section calculating an intensity signal corresponding to a position of each scattering point in the sample medium on the basis of the acquired spectrum, calculating a power spectrum corresponding to the position of each scattering point on the basis of a temporal variation of the intensity signal corresponding to the position of each scattering point, and calculating a diffusion coefficient of the particles corresponding to the position of each scattering point on the basis of the calculated power spectrum.