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.
A coherent light-scattering experiment on an aqueous clay suspension having a concentration that stretches over an extended range was carried on. The far field speckle was recorded in an unconventional manner.
A computer code for image processing, written for this purpose, was used to extract the scattered light intensity. The variation of the average scattered light intensity with the particle concentration was analyzed, and a possible fast procedure for assessing the particle concentration is suggested.
A coherent light scattering experiment was carried out. The samples were aqueous natural water suspensions picked from the same river. While sedimentation occurred in the samples, they were subjected to a dynamic light scattering (DLS) experiment and the time series was recorded at certain time intervals. For each recording, a program written for this purpose, performing at least square minimisation, computed the average diameter of the particles in suspension. The variation of the average diameter in time indicates the dominant type of suspensions in water.
Dan Chicea, Ovidiu Tiţa, Mihaela Tiţa and Ecaterina Lengyel
A coherent light scattering experiment on aqueous suspension of Saccharomyces cerevisia yeast with a concentration that covers five orders of magnitude was performed. The average scattered light far field was recorded using a CCD. A computer code for image processing was written for this purpose and used for providing the first order statistics of the far interference field. The variation of the average speckle size with the particle concentration was analyzed and a very fast procedure for monitoring the yeast concentration is suggested. The possibility of monitoring the fermentation process by a fast assessment of the yeast concentration is suggested, as well.
Using a Lorentzian function fit as reference, a basic experiment was designed for processing Dynamic Light Scattering time series, allowing to estimate the average particle size of a suspension. For fitting the averaged power spectrum of the time series, several neural network configurations were tested in order to compare the results with the reference. The results of this comparison revealed a good match, serving as a proof of concept for using neural networks as an alternative for DLS time series processing.
Silviu Rei, Dan Chicea, Beriliu Ilie and Sorin Olaru
When performing data acquisition for a Dynamic Light Scattering experiment, one of the most important aspect is the filtering and conditioning of the electrical signal. The signal is amplified first and then fed as input for the analog digital convertor. As a result a digital time series is obtained. The frequency spectrum is computed by the logical unit offering the basis for further Dynamic Light Scattering analysis methods. This paper presents a simple setup that can accomplish the signal conditioning and conversion to a digital time series.