Evaporography

a method of producing images of objects by making use of the thermal, usually infrared, radiation of the objects themselves. It was proposed by the German physicist M. Czerny in l929.

In evaporography, either a layer of volatile liquid evaporates from a darkened membrane in a vacuum chamber or, vice versa, the liquid on the membrane condenses from vapor previously introduced into the chamber (Figure 1). The object is projected onto the membrane by a lens, and the image in the form of a liquid relief corresponding to the differences in evaporation or condensation at various points on the membrane is either viewed directly in interference colors or is photographed. The spectral region in which evaporography may be used depends on the properties of the lens and other elements of the apparatus and on the selection of the dark coating of the membrane; in practice, it is possible to produce images in the infrared region up to wavelengths of about 10 micrometers.

Figure 1. Diagram of the process for obtaining an image in evaporography: (1) object, (2) lens (usually infrared), (3) thin darkened membrane, (4) vacuum chamber, (5) liquid relief

Evaporography is primarily used for viewing and photographing in the dark, recording the infrared self-radiation of bodies, the remote measurement of temperature and temperature distributions on the surface of an object (including applications in medical diagnosis), and the visualization of beams from infrared lasers.