Schlieren Flow Visualization is a method to see small differences in air pressure like those around a flame; essentially it allows you to *see* air. It is typically accomplished with super fancy mirrors that can cost upwards of $300. This instructable is about making a Schlieren Flow Visualization really cheaply and pretty easily. If you are curious about my failed attempts before I got it to work then visit my DIR Schlieren Flow page.
Here are all the components you need:
*other cameras might work too but I couldn't get the effect to work with my point & shoots.
The basic idea is you need to get something hot like a candle in the middle of some parallel light rays - then focus those rays back to almost a point – knocking out half of the rays that didn't line up exactly parallel. The first page magnifier makes the light from the LED parallel (collaminated) then the other one focuses the light back again. The camera is placed right where the light focuses and angled to the side so that some non-parallel rays are blocked by the aperture.
You need to position the camera carefully, but patience is an ample substitute for fancy equipment :O