| 摘要 |
PROBLEM TO BE SOLVED: To perform high-accuracy measurement through low distortions detection by reducing higher-order harmonic waves as desired, without reducing the amount of light received. SOLUTION: In this photoelectric incremental encoder, a grating pattern 12 on a scale 10 or Moire fringes generated on the scale 10 is/are guided to a light-receiving element by means of a lens optical system 20. The incremental encoder is provided with a phase grating 40, in which a phase grating pitch P<SB>G</SB>and disposition positions L are determined so that a difference dx in arrival point between + first-order diffracted light and - first-order diffracted light by a phase grating 40 is half the wavelengthλof a higher-order harmonics that are desired to be removed. COPYRIGHT: (C)2007,JPO&INPIT
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