Canadian camouflage experts Hyperstealth Biotechnology has recently applied for patents on their technology which can bend light around an object to make it vanish from sight when placed in its sweet spot. The paper-thin screen could be used to hide military targets from ground-level threats. More on Vimeo.
Schlieren imaging is a method of visualization which plays with light refraction to capture images of normally invisible fluid patterns like air movement. Here, Veritasium walks us through a variant which uses colored filters to produce some astounding images.