Length metrology at NPL covers a many orders of magnitude and in this talk I plan to give an overview of the capabilities of the Length Metrology Group and some of its current research activities. The relevance of the work in the Length Group to science, industry and society today will be illustrated with numerous examples.

Prior to starting at NPL Andrew completed his PhD in x-ray diffraction studies of diamond at Royal Holloway, University of London, and a post doc position at King's College London in the field of x-ray microscopy. In 1990 he joined Albert Franks' Nanometrology group to work on an EC funded project to build a combined optical and x-ray interferometer (COXI) for the calibration of displacement measuring transducers. This was a collaborative project with PTB in Germany and IMGC in Italy. He subsequently used the instrument to measure the non-linearity in a variety of optical interferometers.

Andrew's collaboration with PTB continued in the field of x-ray interferometry when in 2000 he spent 5 months at PTB combining and x-ray interferometer with a scanning tunnelling microscope. More recently he has just returned from a 2.5 year secondment to PTB where he developed an atomic force microscope for the examination of tip sample interactions and their effects on dimensional metrology.