Form error characterization of reflective-type gratings

Yuki Shimizu, Woo Jae Kim, So Ito, Wei Gao

Research output: Chapter in Book/Report/Conference proceedingConference contribution

6 Citations (Scopus)


A form error characterization of a reflective-type scale grating, which is used in three-degree-of-freedom (3-DOF) encoders for position measurement of a planar motion stage, is presented. The scale grating has a micro-structured surface, the pitch of which is 1 μm in both Xand Y- direction. The periodic pattern on the scale grating generates diffracted beams when a laser beam incidents to the grating surface. The ±1st order diffracted beams from the grating contain information about the stage motions of not only X- or Y- directional in-plane displacement but also Z-directional out-of-plane displacement, and are therefore able to be utilized for multi-axis position detection. Accuracies of the position detection are mainly determined by a period deviation and a Z-directional out-of-flatness of the scale grating. The form error characterization of the grating is possible by using Fizeau interferometer, although the form error of a reference mirror in the Fizeau interferometer still remains as a measurement error in the form of the measured scale grating. In this paper, a new method was proposed to evaluate the form error characterization of the scale grating for the 3-DOF encoder, while eliminating the form error of the reference mirror in the Fizeau interferometer.

Original languageEnglish
Title of host publicationEmerging Technology in Precision Engineering XIV
PublisherTrans Tech Publications Ltd
Number of pages6
ISBN (Print)9783037855096
Publication statusPublished - 2012
Event14th International Conference on Precision Engineering, ICPE 2012 - Hyogo, Japan
Duration: 2012 Nov 82012 Nov 10

Publication series

NameKey Engineering Materials
ISSN (Print)1013-9826
ISSN (Electronic)1662-9795


Other14th International Conference on Precision Engineering, ICPE 2012


  • Interferometer
  • Linear encoder
  • Out-of-flatness
  • Period deviation
  • Scale grating

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering


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