| 摘要 |
The optical coder uses 2 offset diffraction gratings (1,2), one of which has 2 grid sections (2A,2B) with transparent and opaque grid elements which are relatively offset by half the grid cons constant. The intensity of the light obtained from the 2 sections (2A,2B) is summated so that the error signal components cancel each other. The 2 diffraction gratings (1,2) are mounted on relatively displaced machine tool components, with the 2 grid sections (2A,2B) positioned next to one another in the displacement direction, or perpendicular to the displacement direction, with an adder (7) combining the positive and negative diffraction spectra of equal order obtained from the 2 grid sections (2A,2B).
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