title: Simultaneous multi-channel absolute position alignment by multi-order grating interferometry.
abstract: A simultaneous multi-channel absolute position alignment system is investigated to determine the absolute position of a grating mark. By employing a multi-order grating interferometer and a multi-channel phase extraction method, many equivalent measurement results are generated simultaneously for stable and consistent measurement. By combining measurement results of different orders, low-order signals enabled large unambiguous measurement ranges, and high-order signals enhanced the measurement accuracy. Comparison experiments performed using an incremental HeNe reference interferometer yielded the standard deviations of smaller than 11.48nm under laboratory conditions. The proposed scheme will enable a new class of absolute position alignment system for industrial applications.
authors.forename: Zhang
authors.initials: Z
authors.lastname: Tao
authors.forename: Jiwen
authors.initials: J
authors.lastname: Cui
authors.forename: Jiubin
authors.initials: J
authors.lastname: Tan