Editorial

Abstract

High-accuracy dimensional metrology plays a vital role in the manufacturing, aerospace and precision engineering industries through its provision of national and international traceability and conformity. The measurement of length, displacement, distance and angle, for example, and the characterization of surfaces and three-dimensional shape and form, find application across a very wide range of magnitudes, from sub-atomic displacements to large engineering structures. This special issue on dimensional metrology covers a multitude of new and recent metrological research techniques and applications within this broad subject area, from a variety of international precision metrology laboratories. The papers are loosely grouped according to their particular field of dimensional metrology. Early on in the issue, there are a number of papers dealing with interferometrically based measurements for high-accuracy length, displacement and distance measurements, with an emphasis on heterodyne, modulated and swept-frequency approaches. These papers target a variety of range measurements from 100 metres down to 100 millimetres, with accuracies in the micrometre range for the air-based distance measurements, to sub-nanometre accuracies and picometre-type resolution for environmentally shielded etalons. Following on from these, we have papers concerned with the measurement of diameter and angle to various accuracies, by means of different techniques including precision rotary tables, ring laser goniometry and x-ray interferometry with nanoradian resolution. Another group of papers addresses the measurement of dimensional properties such as length, grating pitch and indenter geometry, by recourse to scanning force microscopy. These lead on naturally to diode-laser-based surface profilometry and surface characterization by confocal optical microscopy, high-resolution two-dimensional calibration and pattern generation techniques. Accuracies here are in the nanometre to sub-nanometre range. In addition, there are papers on experimental techniques for large-scale surface flatness measurement, interferometric lens testing, triangulation sensor error analysis, computer-based aberration compensation and modelling of three-dimensional surface contact in abrasive machining. As guest editors of this special issue, we are pleased that the contributed papers are able, in general, to offer different perspectives of metrological problems within the various subject areas of the issue. These all go toward providing the reader with a wide-ranging view of current international capabilities in dimensional metrology. In recognition of this, we would like to offer our thanks to all the contributing authors, the referees engaged in the review process, and the IOP Publishing team for making this a successful special issue. Horst Kunzmann, Physikalisch-Technische Bundesanstalt, Germany Patrick Gill, National Physical Laboratory, UK Guest Editors July 1998