Pitch-modulated phase grating and its application to displacement encoder

A. Ieki, K. Matsui, M. Nashiki, K. Hane

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)


A binary phase grating with modulated pitch is investigated for a simple displacement encoder. The grating consists of a binary phase grating to eliminate the zeroth-order diffraction, and the pitch of the grating is modulated to compensate the higher harmonics of the encoder displacement signal. Therefore, an undistorted sinusoidal signal as a function of displacement is obtained by simply superimposing a conventional binary grating on the pitch-modulated phase gratings for any air gap between the gratings. The characteristics of the proposed gratings and the encoder signal are investigated by the Fresnel diffraction theory. The proposed grating has been fabricated lithographically, and the signal was examined experimentally. Considering these results, the proposed technique can suppress interpolation error and will be useful for an encoder in precision machining.

Original languageEnglish
Pages (from-to)1213-1225
Number of pages13
JournalJournal of Modern Optics
Issue number7
Publication statusPublished - 2000 Jun

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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