1 July 1990 Moire signals of circular gratings and its application to precise alignment
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Proceedings Volume 1319, Optics in Complex Systems; (1990) https://doi.org/10.1117/12.34719
Event: 15th International Optics in Complex Systems, 1990, Garmisch, Germany
Abstract
The moire interference phenomenon caused by the circular diffraction gratings under coherent illumination is studied to utilize it for precise alignment. The phenomenon is investigated by the Fresnel Kirchhoff's diffraction theory. The characteristics of the moixe signals in the diffracted beams are examined as a function of the lateral displacement and the airgap between the gratings. The moire signal obtained in the first order diffracted beam has been employed to the precise short-range alignment. The alignment system consists of a phase shifted pair of circular gratings and a stage driven by piezo-electric atuators. The system is controlled by the micro-computer to keep the alignment position. The alignment has been carried out with the precision of few tens of nm.
© (1990) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Kazuhiro Hane, Toshio Goto, Shuzo Hattori, "Moire signals of circular gratings and its application to precise alignment", Proc. SPIE 1319, Optics in Complex Systems, (1 July 1990); doi: 10.1117/12.34719; https://doi.org/10.1117/12.34719
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