High resolution optical encoders take advantage of diffraction and interference properties of light. In such components, the scale is a phase grating that diffracts light into several orders; an optical reading system makes two of them to interfere. In state of the art systems, the orders interfere after they have been spatially separated from other orders; this leads to cumbersome reading heads. A compact, fully diffractive optical reading system was designed and realised. This reading system was used for the realisation of rotation encoders. Using the competences of the Eureka EU 922 FOTA project partners, the encoder phase gratings were successfully realised and the reading system was implemented in standard rotation encoder housings. Without interpolation the encoder gives 480'OOO pulses per revolution with a repeatability of 2.5 pulses.

By patterning the iron oxide film of a conventional iron oxide 0. Parriaux mask it is possible to obtain a binary phase grating of high diffraction H. Vuilliomenet efficiency and high transmission that can be used in high-resolution dis-CSEM Centre Suisse d'Electronique et de placement sensors. Microtechnique SA Jaquet-Droz 1 Subject terms: iron oxide mask; iron oxide film; binary phase grating; high-CH-2007 Neuchâtel, Switzerland resolution displacement sensors.

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