What is a schilieren?

Answer 1

Schlieren is an optical technique used to visualize changes in the refractive index of transparent media, often employed in fluid dynamics to observe airflow and thermal gradients. It typically involves the use of a light source, a collimating lens, and a knife-edge or other blocking device to create high-contrast images of the variations in density. Schlieren Photography can reveal phenomena such as shockwaves, heat plumes, and other subtle flow patterns that are otherwise invisible to the naked eye. This technique is particularly valuable in scientific research and engineering applications.