Color enhanced transmission electron micrograph (TEM) of a germanium-and-carbon replica of diffraction grating on a 200-mesh, 3.05 mm grid. The diffraction grating itself consists of a glass plate or a mirror with a large number of equidistant parallel lines or grooves on its surface; it is used to disperse a beam of light (or other electromagnetic radiation) into wavelengths to produce a spectrum. This has a spacing of 462.9nm, 2160 lines per millimeter, ideal for calibrating electron-optical magnification up to the x80,000-100,000 range. The ridges of the grating are sharp (light in color, as if lighted from the left upper corner) and the "valleys" are dark and contain some very fine debris. Image width: 11 micrometers. Magnification: 9100x if printed 10 cm wide.