Estimating Particle Concentration in Natural Water by Speckle Contrast

A coherent light scattering experiment was carried out on an aqueous clay suspension with an extended range of concentrations. The far field speckle was recorded as a video recording in an unconventional manner using a charged coupled device. A computer code for image processing, written for this purpose, was used to compute the average far field contrast. The variation of average contrast with particle concentration was analysed, and a possible fast procedure for assessing the particle concentration over an extended concentration range was suggested.