The bullet, passing at a close distance in front of a photographic film plate is illuminated by a short duration light flash, which must be concentrated in a point. The flash can be triggered by a light barrier for example. No camera or optical lens is required for this technique. The shadowgraph displays the flowfield structure in the vicinity of the moving body.
Some typical set-up parameters of an experiment
|Distance of bullet to film plate||a few centimeters|
|Distance of point spark light source to film||2 - 3 meters|
|Flash duration||1 ms or less|