Definition of Tomograph

Tomograph: The apparatus for generating a tomogram, a two-dimensional image of a slice or section through a three-dimensional object. The tomograph achieves this remarkable feat by simply moving an x-ray source in one direction as the x-ray film is moved in the opposite direction during the exposure to sharpen structures in the focal plane, while structures in other planes appear blurred.

The tomogram is the picture; the tomograph is the apparatus; and tomography is the process.