Patent ID: 7280231

Claim:
An apparatus for determining a wall thickness of a microcapsule whose wall has a refractive index n 1 , comprising: detecting means for detecting a light scattering intensity data I 1 with respect to the microcapsule dispersed in a medium having a refractive index n 1 , and a light scattering intensity data I 2 with respect to the microcapsule dispersed in a medium having a refractive index n 2 ; memory means for storing a theoretical equation for correlating a characteristic of a light scattering intensity with a particle size; and computing means for calculating an inner diameter r 1 and an outer diameter r 2 of the wall, from the theoretical equation based on the light scattering intensity data I 1 and I 2 , and calculating a wall thickness (r 2 −r 1 ).