Schlieren Optical Technique Makes the Invisible Visible

A point source of light is reflected from a concave mirror and focused onto the edge of a razor blade, which is mounted in front of the camera. Light refracted near the mirror and intercepted by the blade gives the illusion of a shadow. Seen here are the heated gases from a candle flame and a hair dryer, helium gas, and sulfur hexafluoride gas. Schlieren (German, meaning "streaks") were first observed by Robert Hooke in 1665 using a large convex lens and two candles.

Liked the Posts? Please Click the button below to Share...