shadowgraph

Short definition from Wiktionary

Noun

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

Verb

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