Simultaneous determination of particle size and density by LDV

A new laser Doppler particle measuring system is proposed that can detect not only the particle size but also its density. In this system knowledge of amplitude and phase of the particl's response for forced vibration is sufficient to determine the two parameters. As a practical example, bispectral analysis is applied to the laser Doppler vibration measurement, so that the amplitude and phase of the particle's vibration can be measured even under fairly noisy circumstances. The experimental results show that this system is effective.