| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-precision and small-sized optical encoder. SOLUTION: The diffraction grating encoder comprises a scale 81 on which a scale grating 80 is formed, a light source 280 for illuminating the scale grating 80 with light, and an optical fiber read head 300 of which the tip portion, together with the light source 280, can be moved relative to the scale 81 in the direction of a measurement axis 82. The read head 300 has a plurality of optical fiber receiver channels 190A to C which receive a self-image 265 formed on a predetermined position by means of the light from the scale grating 80. The receiver channel 190 has an optical fiber 130, a receiver channel opening 110 formed at one end of the optical fiber 130, and a phase mask 120 formed on the opening 110. The phase mask 120 has a grating with a period corresponding to a light and shade period formed on the self-image. The gratings for the plurality of receiver channels 190 have a different spatial phase relationship. COPYRIGHT: (C)2004,JPO
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