Analysis of a Surface Encoder in Wave Optics

Y. Watanabe, W. Gao, H. Shimizu, S. Kiyono

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


A surface encoder for position measurement of machine tool carriages, which is composed of a 2-D angle grid and a 2-D slope sensor, is analyzed in wave optics. Modeling the optical system of the surface encoder based on interference and diffraction is carried out. The 2-D angle grid surface, which is a superposition of the X- and Y-directional sine waves, is treated as a phase grating with a phase shifting function. The components of the slope sensor are also modeled precisely to obtain the actual intensity distribution of the light spot on the photodetector (QPD) of the sensor. Feasibility of the proposed wave optics model of the surface encoder has been confirmed by results of simulation and experiment.

Original languageEnglish
Pages (from-to)219-224
Number of pages6
JournalKey Engineering Materials
Publication statusPublished - 2004


  • Machine Tool Carriage
  • Position Measurement
  • Surface Encoder
  • Wave Optics


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