Schlieren Imaging

Schlieren imaging, also referred to as schlieren photography, is a fascinating optical technique. It can be used to help visualize heat flow through the air. This makes it an interesting tool in thermal engineering.

How does schlieren imaging work?

To understand schlieren optics, first we must talk about air, temperature, density, and refractivity. The density of air depends on temperature. Cooler air will have a higher density, and warmer air will have a lower density. This is why heat rises: the cooler, denser air settles down while the warmer, less dense air floats upwards.

When different air pockets have different densities, they refract light in different ways. This difference in refraction is what schlieren cameras are trying to capture. By using an intricate setup that includes mirrors, a point light source, and a knife edge or razor blade, schlieren optics can record images that show differences in the refractivity of air.

Schlieren setups work with both still cameras and video cameras. Still cameras just capture a snapshot; but if you use a video camera, you can actually watch heat move through the air. Pretty cool, right? We think so!

Check out one of our blog posts below, which includes a video demonstration using the schlieren technique.