TABLE OF CONTENTS Micromachining is a key technology in the important fields of microimprinting, scanning microscopy, microlithography and automated alignment. A large proportion of these machines require accurate positioning of tools or probes with respect to a workpiece. Thus, much challenges behind the metrology is concerned with the accurate measurement of absolute positions and the subsequent reduction of the geometrical errors associated with this position. Compensation for geometrical errors in machines has been applied to Co-ordinate Measuring Machines (CMMs) and machine tools to minimise the relative position errors between the end-effector of the machine and the workpiece (Hocken 1980). Given an adequate machine design, a large proportion of these errors are completely repeatable and reproducible, and therefore amenable to modelling and compensation. While widespread incorporation of error compensation in machine tools has remained to be seen, the application in CMMs is tremendous and today, it is difficult to find a CMM manufacturer who does not use error compensation in one form or another (Hocken 1980). The development in error compensation is well documented by Evans (Evans 1989). Early compensation methods utilised mechanical correctors, in the form of leadscrew correctors, cams and reference straightedges. Maudslay and Donking, for example, used leadscrew correction to compensate for the errors in their scales producing machine. Compensation via mechanical correction, however, inevitably increases the complexity of the physical machine. Furthermore, mechanical corrections rapidly cease to be effective due to mechanical...
