x-ray

   or X-ray or x ray or X ray

   A photon with a wavelength approximately 0.01 to 10 nanometers. photo of an xray of a handMore likely a stream of such photons, also known as roentgen rays (after Wilhelm Konrad Roentgen, the discoverer of x-rays and developer of x-ray photography). X-ray may also refer to a photograph taken with x-rays, also called a radiograph. Radiographs are most commonly made by physicians of course (as done to see the bone structure of a human see thumbnail to lefthand or see thumbnail to righthead), but are also made of art objects to better see what is beneath their surfaces, in hopes of revealing information about their making, and alterations over time. Typical examples are radiographs of mummies, and of paintings that have been painted over, are in need of conservation, or are suspected forgeries. Also see angstrom, infrared reflectography (IR) and reflectogram, overpainting, and ultraviolet.