A method to measure the distance among scatters and the scatters' diameter in artificial composite materials

A new method to measure the distance among scatters, the density of scatters, and the scatters' diameter in artificial composite materials has been proposed. This method is based on detecting the reflection amplitude change (amp) of the echo signal reflected from scatters. Simulation results show that such a method is valid for the distance less than four times of the acoustic wavelength, because the coupling between the scatters can be neglected for the distance larger than four times of the acoustic wavelength. Therefore, this new measure method can be always valid by choosing appropriate frequency according to the scaling rule discussed in this paper. At the same time, it is found that the diameter of scatters is the half of the wavelength where the curve peak of the amp vs frequency occurs. It implies that such a new method can also be used to measure the diameter of scatters in solids and liquids, and even in PM2.5 pollution particles in air.