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Optical Engineering

Measurement of six-degree-of-freedom planar motions by using a multiprobe surface encoder
Author(s): Xinghui Li; Yuki Shimizu; Takeshi Ito; Yindi Cai; So Ito; Wei Gao
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Paper Abstract

A multiprobe surface encoder for optical metrology of six-degree-of-freedom (six-DOF) planar motions is presented. The surface encoder is composed of an XY planar scale grating with identical microstructures in X- and Y-axes and an optical sensor head. In the optical sensor head, three paralleled laser beams were used as laser probes. After being divided by a beam splitter, the three laser probes were projected onto the scale grating and a reference grating with identical microstructures, respectively. For each probe, the first-order positive and negative diffraction beams along the X- and Y-directions from the scale grating and from the reference grating superimposed with each other and four pieces of interference signals were generated. Three-DOF translational motions of the scale grating Δx, Δy, and Δz can be obtained simultaneously from the interference signals of each probe. Three-DOF angular error motions θX, θY, and θZ can also be calculated simultaneously from differences of displacement output variations and the geometric relationship among the three probes. A prototype optical sensor head was designed, constructed, and evaluated. Experimental results verified that this surface encoder could provide measurement resolutions of subnanometer and better than 0.1 arc sec for three-DOF translational motions and three-DOF angular error motions, respectively.

Paper Details

Date Published: 12 May 2014
PDF: 7 pages
Opt. Eng. 53(12) 122405 doi: 10.1117/1.OE.53.12.122405
Published in: Optical Engineering Volume 53, Issue 12
Show Author Affiliations
Xinghui Li, Tohoku Univ. (Japan)
Yuki Shimizu, Tohoku Univ. (Japan)
Takeshi Ito, Tohoku Univ. (Japan)
Yindi Cai, Tohoku Univ. (Japan)
So Ito, Tohoku Univ. (Japan)
Wei Gao, Tohoku Univ. (Japan)

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