Lippmann plate

A Lippmann plate records colour as a depth-dependent optical structure in a photographic emulsion. A standing wave writes a spacing; wave interference during later illumination selects the reflected wavelengths. This makes a photographic plate a spatial record of an optical spectrum. The striking idea is that information about colour can live in geometry.

Gabriel Lippmann presented his colour process in 1891 and received the 1908 Nobel Prize in Physics. His career belongs principally to physics: he held chairs in mathematical and experimental physics.^{[ref] [ref]}