Photomicrograph of a crystal.
© National Media Museum / Science & Society Picture Library
"Photomicrograph of interference pattern - study of polarised light through crystal, 1851. Salt print photomicrograph of a crystal by English pioneer of photography William Henry Fox Talbot (1800-1877). Talbot invented the first negative/positive process, whereby for the first time any number of prints could be made of a single image (from the negative). This is known as the calotype process. A photomicrograph is a photograph taken using a microscope. Dimensions of photograph: 620mm x 630mm."