The focus of this thesis was to use our knowledge on light-matter interaction to unravel the complex internal dynamics, at the microsecond and nanometer scale, of tiny liquid droplets impacting a surface by developing a new tool, High-speed Laser Speckle Imaging (HS-LSI). The scientific questions that were asked and answered during this project, could be exploited in a number of fields. The primary one is the printing industry which utilizes ink jet technology, a ubiquitous and
commercial technology. For the scientific community, these studies and the
instruments we built, enable a better understanding of experiments involving
multiple scattering of light inside opaque materials especially on short time scales
and small length scales.