| 摘要 |
PURPOSE: To provide an optical encoder that is able to output a phase difference in a detection signal in an accurate manner. CONSTITUTION: One second slit 21 alone, serving as two functions of an illuminant slit and an index slit, is installed in a fixed scale 2, and light receiving elements 4 are disposed in a 2×2 row type each, thereby finding an azimuth angleϕand a roll angleθof the fixed scale 2 where a phase difference in a detection signal is shifted as far as by 90 degrees at a time. At this time, the fixed scale 2 is tilted as far as the angle to a moving scale 1, whereby the index slit, where the phase difference in the detection signal is shifted as far as 90 degrees at a time, is thus set.
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