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Using speckle patterns in a direct positioning system (2014)

Bloem, A.; Foremny, E.; Schenck, C.; Kuhfuß. B.:

Proceedings of the 4th International Conference on Nanomanufacturing (nanoMan 2014), 8.-10. July 2014, Bremen

Abstract

In the production of micro components in linked parts continuous feeding systems, e.g. belt conveyors, are used. The accuracy of these systems can be increased by using a direct position measuring system. One possibility is to apply a grating structure as a length scale standard directly onto the linked parts, for example via embossing. However, this is complex, costly and prone to dimension faults. Another approach is to use the material of the linked part itself as a material measure. Due to the existing surface roughness a speckle pattern can be obtained by applying coherent light. These patterns can be recorded with a suitable optical measurement system. A shift of the linked part results in a dependent shift of the recorded speckle pattern. An extended cross correlation method is presented and discussed to calculate the actual movement. The achievable resolution with this system is about 0.1 μm while the accuracy is about 4 μm on a distance of 9 mm.