ANDREW BROOKES, NATIONAL PHYSICAL LABORATORY / SCIENCE PHOTO LIBRARY ANDREW BROOKES, NATIONAL PHYSICAL LABORATORY / SCIENCE PHOTO LIBRARY
Ultraviolet (UV) cleaning. Platinum-iridium kilogram mass prototypes being cleaned with UV light and ozone. First, UV light at a wavelength of 185 nanometres creates ozone, which bonds with hydrocarbon contamination on the metal surface. A second UV wavelength at 250 nanometres then breaks these bonds, releasing the contamination in the form of carbon dioxide. Photographed at the National Physical Laboratory, Teddington, UK.
Model release not required. Property release not required.