1 Dynamic Light Scattering

A dynamic light scattering apparatus was built with a HeNe laser; the beam incident on a sample of particles(microspheres of one or multiple diameters or casein undigested and digested) suspended in water scatters into a random pattern product of the coherent superposition of the outgoing waves scattered from the spheres. Because the spheres are in constant Brownian motion, the pattern randomly changes in time. A phomultiplier tube was placed in the pattern and the random fluctuations in the light intensity were measured and analyzed. The signal’s autocorrelation functions were computed to verify the spheres ’ diameter. The results show that the apparatus is able to measure the diameter of single sized particles but not on a mixture with two different size microspheres. Further analysis needs to be done in order to determine the size of protein digested fragments