Crossover from Ballistic to Brownian Motion

In this project we are interested in studying the ballistic diffusive crossover in a free liquid.  In 1827, Robert Brown observed a speck of pollen floating in water moving in diffusive motion.  In 1905, Albert Einstein showed that diffusive motion was caused by the pollen being hit by individual water molecules.  Fundamental to this theory is that for very short time scales the pollen is moving ballistically.  The goal of this experiment is to observe a particle, suspended in a liquid, transition from ballistic to diffusive motion. To observe this behavior we use a homemade holographic microscope in conjunction with a high-speed camera.