Schlieren Flow Visualization

Schlieren imaging is a flow visualization method that takes advantage of changes in the density and index of refraction of a fluid. Light is projected through the medium and into a camera. However, before the light reaches the camera, some of the refracted light is blocked, usually by a knife edge.

Since the equipment (particularly the parabolic/spherical mirrors) needed for this is expensive, I borrowed some from Cal Poly's Mechanical Engineering Department. One constraint is that the size of the imaging field is related to the size (and cost) of the mirrors.

The setup I used is considered a "Z" formation (as opposed to the "V" setup that is also commonly used) due to the shape of the path that the light takes from the source to the camera. Most setups are monochrome since the knife edge (in this case, the edge of a piece of aluminum foil taped to a cardboard cutout) simply blocks refracted light and produces dark areas on the image. I experimented with replacing the knife edge with color filters, which produced some interesting and colorful results.