Nanoindenter for hardness testing. This nanoindenter determines a material's hardness by measuring its resistance to forces exerted on it by a harder material. It uses a fine tip made from a very hard material, such as diamond, to produce an indentation that is only a few nanometres (billionths of a metre) in size. An atomic force microscope (AFM) is then used to examine how the test material has responded to the exerted forces Photographed at the National Physical Laboratory, Teddington, UK.