| 摘要 |
PROBLEM TO BE SOLVED: To provide a magnetic encoder which is suitable for a surveying instrument and in which a plurality of harmonic errors at arbitrary orders can be simultaneously corrected. SOLUTION: The magnetic encoder is provided with a magnetic drum 53 which comprises multipolar magnetized layers 53a equally divided and magnetized at a pitchλon the outer circumferential face and four magnetic sensors 541 to 544 arranged along the layers 53a. In the magnetic sensors 541 to 544, two each of the magnetic sensors 541, 542 and 543, 544 are formed as one set each in order to correct two harmonic errors at an n order and a m order, and the respective sets of the magnetic sensors 541, 542 and 543, 544 are arranged in such a way that their phases are deviated by an expression of 2πP1+π/n or 2πP2+π/n (where P1 and P2 represent arbitrary integers), and the respective sets of the magnetic sensors 541, 542 and 543, 544 are arranged in such a way that their phases are deviated by an expression of 2πP3+π/m (where P3 represents an arbitrary integer).
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