Title: A double pass surface encoder for measurement of planar motion

Authors: Yoji Watanabe, Wei Gao, Satoshi Kiyono

Addresses: Faculty of Engineering, Department of Nanomechanics, Nanosystems Engineering Laboratory, Tohoku University, Japan. ' Faculty of Engineering, Department of Nanomechanics, Nanosystems Engineering Laboratory, Tohoku University, Japan. ' Faculty of Engineering, Department of Nanomechanics, Nanosystems Engineering Laboratory, Tohoku University, Japan

Abstract: This paper describes a double pass surface encoder, composed of a 2D sinusoidal grid and an optical sensor, for nanometer position measurement in the XY plane. By using a double pass optical layout, the sensitivity becomes twice as much as that of the single pass encoder. From a wave optics simulation, the grid amplitude of 70 nm is selected. The experimental result shows that the sensor has a resolution higher than 5 nm. The interpolation error is 0.6 µm in both the X- and Y-direction. The extrapolation errors in the X- and Y-direction are 0.18 µm and 0.23 µm.

Keywords: planar motion measurement; nanometer position measurement; microstructured surfaces; optical sensors; double pass encoders; surface encoders; sinusoidal grid; surface stage; wave optics simulation; nanotechnology; surface engineering.

DOI: 10.1504/IJSURFSE.2007.013622

International Journal of Surface Science and Engineering, 2007 Vol.1 No.1, pp.80 - 99

Available online: 09 May 2007 *

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