False-color shadowgram of gunshot from a .357 magnum by Gary Settles at Penn State university.
The New York Times has an awesome slideshow of shadowgrams and Schlieren photographs, created by engineering professor Gary Settles, which accompany a 2008 article about his work at Penn State’s Gas Dynamics Lab. The method, which can produce fantastic visualizations of fluid flow in turbulent systems, is amazingly simple. I am surprised there aren’t more hobbyists doing it.
14 thoughts on “Shadowgrams and Schlieren photography”
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If it’s so simple, how about a link telling us how?
dan
Just call me dumb but that wikipedia quote made no sense to me, even with the help of a dictionary. The rest of the world may not be as apt in physics – hence the lack of Schlieren photography among hobbyists (which may also include lots of soccer moms), or any tutorials for that matter.
There are no online tutorials that I know of, but like I say, it’s incredibly simple, as a minute’s research reveals. From the Wikipedia article on Schlieren Photography:
“The basic optical schlieren system uses light from a single collimated source shining on, or from behind, a target object. Variations in refractive index caused by density gradients in the fluid distort the collimated light beam. This distortion creates a spatial variation in the intensity of the light, which can be visualised directly with a shadowgraph system.”
Which amounts to:
“Make bright, focused shadows of the system you want to study and photograph them while the system is in operation.”
A quick google provided: http://people.rit.edu/andpph/text-schlieren.html
I googled for a bit and didn’t find a whole lot of info for the DIYer, however this image gave me an idea:
http://www.americanscientist.org/Libraries/images/2005122153046_846.jpg
Use a tightly focused flash, small combiner and old projector screen and you should be able to make high speed Schlieren images with the high speed photo kit from the maker store.
I have been playing around with this for about a year and have a web page up about it.
It IS simple.. once you figure out all the “obvious” things that tend to get left out when describing it. It took me a while to get all the details right, and shortly I hope to add to my page a better description of what is going on.
http://www.ian.org/Schlieren/
The only hard part to find is the mirror. A six inch spherical mirror from Edmund Optics will run about $50 which is not too bad. Mirrors get expensive FAST as they get bigger.
Thank you, thank you, thank you! Your page will be up on the feed Monday morning.