Cameras capable of capturing videos at a trillion frames per second allow to
freeze light in motion, a very counterintuitive capability when related to our
everyday experience in which light appears to travel instantaneously. By
combining this capability with computational imaging techniques, new imaging
opportunities emerge such as three dimensional imaging of scenes that are
hidden behind a corner, the study of relativistic distortion effects, imaging
through diffusive media and imaging of ultrafast optical processes such as
laser ablation, supercontinuum and plasma generation. We provide an overview of
the main techniques that have been developed for ultra-high speed photography
with a particular focus on `light-in-flight' imaging, i.e. applications where
the key element is the imaging of light itself at frame rates that allow to
freeze it's motion and therefore extract information that would otherwise be
blurred out and lost.Comment: Published in Reports on progress in Physic
