Is a city-scale version of this possible?
Schlieren Optics – See small changes in the index of refraction in air
11–20 of 32 posts
Re: Schlieren Optics – See small changes in the index of refraction in air
#12And it's kindof accessible for hobbyists, here is the website of one individual who made his own setup: http://www.ian.org/Schlieren/ The most expensive component (except the camera) is the mirror. According to that website, it costs about $100 from an optics company.
You can also do it without any mirror, using Background Oriented Schlieren. Basically, you print a bunch of random dots on paper, and use a camera to see the subpixel shifts in the dots. ( see http://en.wikipedia.org/wiki/Synthetic_schlieren ). By cross-correlation, you get the change in refractive index/density of air.
One of the main limitations on a Schlieren system is that you can only image objects that are smaller than your mirror. That makes the BOS systems are pretty neat, because at least in theory, you can just print out large backgrounds to image large areas.
Re: Schlieren Optics – See small changes in the index of refraction in air
#13Purely out of curiosity, has anyone used this in conjunction with a linguistics study to visualise sounds made during speech? I did a quick literature search but couldn't find anything. Not sure whether if features would be too subtle to see anything interesting...
Edit: Spoke too soon. Did find one paper[1] (though I can't read it) which uses it to compare the production of 's' and 'z' sounds. Would love to know if there are any more papers though.
Re: Schlieren Optics – See small changes in the index of refraction in air
#14This is basically the same effect you see with shimmering above a hot road surface.
Or the effect you can see after about second 30 in the following pretty[1] video of a plane passing in front of a mountain range (the narrow band of light behind it works well enough as a collimator).
https://www.youtube.com/watch?v=wOUuj1LQRyk
[1] it could use some image stabilisation though.
Re: Schlieren Optics – See small changes in the index of refraction in air
#15And it's kindof accessible for hobbyists, here is the website of one individual who made his own setup: http://www.ian.org/Schlieren/ The most expensive component (except the camera) is the mirror. According to that website, it costs about $100 from an optics company.
You can also do it without any mirror, using Background Oriented Schlieren. Basically, you print a bunch of random dots on paper, and use a camera to see the subpixel shifts in the dots. ( see http://en.wikipedia.org/wiki/Synthetic_schlieren ). By cross-correlation, you get the change in refractive index/density of air. One of the main limitations on a Schlieren system is that you can only image objects that are smal…
This paper is really nice http://www.ualberta.ca/~bsuther/papers/procsorrento0998/repr... on the synthetic method.
Re: Schlieren Optics – See small changes in the index of refraction in air
#16And it's kindof accessible for hobbyists, here is the website of one individual who made his own setup: http://www.ian.org/Schlieren/ The most expensive component (except the camera) is the mirror. According to that website, it costs about $100 from an optics company.
Or you can grind your own mirror, which is a fun project. The Foucault tester, used to see the Schlieren image is also used for that project. It is easy to see the bump created on the mirror due to its expansion after briefly touching it with your finger.
Re: Schlieren Optics – See small changes in the index of refraction in air
#17Reddit front page is leaking onto HN.
Re: Schlieren Optics – See small changes in the index of refraction in air
#18I'm super-curious about how something similar might be happening in the Double-Slit Experiment.
Re: Schlieren Optics – See small changes in the index of refraction in air
#19And it's kindof accessible for hobbyists, here is the website of one individual who made his own setup: http://www.ian.org/Schlieren/ The most expensive component (except the camera) is the mirror. According to that website, it costs about $100 from an optics company.
You can also do something related with materials that are not as common as they used to be but still available. If you take a piece of photo paper and put it in the background ( in the dark or course) and then shoot a strobe through the "disturbance" you'll get a shadow picture of e.g. A bullet and its shockwave (assuming the strobe is triggered at the right time). We did this sort of thing in Doc Edgerton's lab. For many years there was a Schliieren photo that Kim Vandiver made downstairs from the lab.
Re: Schlieren Optics – See small changes in the index of refraction in air
#20And it's kindof accessible for hobbyists, here is the website of one individual who made his own setup: http://www.ian.org/Schlieren/ The most expensive component (except the camera) is the mirror. According to that website, it costs about $100 from an optics company.
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