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The authors have being working on a new position detection method, which can detect two-dimensional position of an xY stage with a single sensor [1]. Conventionally, position detection is carried out by utilizing either a linear scale or a laser interferometer [2]. Displacement probes like capacitance-type probes or laser displacement probes are also used for position detection in short ranges. Basically, such measuring instruments are for one-dimensional measurement. It is necessary to increase the number of sensors for detecting multi-degree-of-freedom positions. This makes the measuring system complicated and expensive. The uncertainty of measurement could also be increased with the increase of number of sensors. In the new position detection method proposed by the authors, a two-dimensional angle grid and a two-dimensional angle senor are utilized [11. The angle grid has a two-dimensional angular pattern on the surface. The two-dimensional position between the angle grid and the angle sensor in the XY plane can be detected simultaneously from the output of the angle sensor. Since only a single probe is used, the problems in the conventional methods could be overcome. In order to realize this new position measuring system, it is necessary to develop a machining method of the specially designed angle grid. The angle grid has two-dimensional sinusoidal micro-patterns on its surface with a wavelength on the order of several hundreds of microns and an amplitude on the order of several hundreds of nanometers. The micro-pattern should be generated over a large area to ensure the measurement range. A machining system based on diamond turning with the fast tool servo technique [3 has been constructed for generating the micro-patterns. To accurately generate the micro-pattern, it is desired to monitor the machining force in the machining process. In this paper, an instrument was designed and fabricated to monitor the machining forces during diamond turning of such micro-patterns. Instrument design and measurement results are presented.
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