shadowgraph

Etymology
From.

Noun

 * 1) A shadow-picture; a radiograph or X-ray photograph; a sciagram.
 * 2)  An optical technique of visualizing patterns of fluid flow by using differences in refractive index
 * 1)  An optical technique of visualizing patterns of fluid flow by using differences in refractive index

Verb

 * 1)  To outline in a shadow-picture on a screen.
 * 2)  To take a picture by means of X-ray, radium, or similar source of actinic radiation.