Visualizing Heat With Schlieren Photography

[Kevin] wanted to check out the air patterns present when his 3D printer is in action. This is useful research; slight differences in temperature can affect the quality of his prints. Instead of something like a thermometer, [Kevin] decided to use Schlieren photography to visualize the air around his 3D printer.

If you’ve ever seen very old-school pictures of supersonic research, you’ve seen Schlieren photography. It’s a way of visualizing the density of transparent objects using only mirrors, lenses, and a point light source. The resulting pictures are usually black and white, although some amazing color pictures exist of bullets traveling through the air next to soap bubbles and candles.

The process of creating a Schlieren photograph is actually pretty easy. [Kevin] pointed a light at a used a 4-inch parabolic mirror placed behind his printer. A knife edge is placed at exactly twice the focal length of the mirror, and after putting a camera behind this knife edge, differences in the density of the air are visible.

From [Kevin]’s video of his Schlieren setup (available after the break), you can see the air is extremely turbulent around his print. That might have been obvious given the presence of a cooling fan, but it’s still very, very cool to look at.


12 thoughts on “Visualizing Heat With Schlieren Photography

  1. The same effect can be had by using sunlight passing through the volume you intend to photograph, because the sun is pretty much a point source. The air casts a shadow where the turbulence is visible.

  2. Seriously H.A.D. you need to get Mr. Benchoff doing something else other than writing… It is obvious that this guy not only does his research poorly before writing, but he doesn’t even write correctly. factual, grammatical, and spelling errors are one thing that a writer should be able to avoid. And for those of you who judge this comment only on this one post of Brian Benchoff’s, go back and read a few of his other articles…

  3. “That might have been obvious given the presence of a cooling fan, but it’s still very, very cool to look at.”

    You should try looking at a paper cup full of coffee using a FLIR camera. Cool indeed.

  4. One of the thing I’ve always thought was neat is how the mere placement of that knife edge changes the image from a second derivative of the density to an image of the first derivative.

    Without the knife edge, columnar light is useful for a lot of things, like flight simulators, machine vision, optical comparators and measurement.

    1. And while I’m thinking of it, Professor J. Kim Vandiver of MIT has 2 nice PDFs on the setup of a Schlieren with color filters. Setting up the 4 knife edges is a little tougher, but the filter is as simple as red,green blue and yellow celluloid filters, tape and 4 knife edges/ razor blades.

      Edgerton’s lab must have been a lot of fun to be at back in the day.

  5. You do not need a parabolic mirror but a spherical mirror.
    This setup is in fact a foucault tester setup. So you need to have spherical mirror to achieve a gray pattern on the mirror, not a donuts one (which is what you have with parabolic mirror).

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.