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摘要

PROBLEM TO BE SOLVED: To solve problems wherein an orthogonal two-phase signal of a homodyne optical interferometer used for a high-precision length measuring system or the like includes an error by an optical system and electric circuit system, the Lissajous's waveform is out of round, and the error becomes a position error as it is when the measuring result is used and positional servo is applied in real time.;SOLUTION: The signal including the error is converted into the polar coordinate, and then a correction value (amplitude, zero point, and phase difference) of the orthogonal two-phase signal of the interferometer is determined by a least squares method based on the relation between the phase angle and radius variation. Based on these values, the orthogonal two-phase signal of the interferometer is corrected so that the radius of the polar coordinate is constant, and the periodic error is reduced. The orthogonal two-phase signal of the interferometer is converted into the polar coordinate, then calculation for emphasizing only a changed part of the radius element is performed, it is converted into the orthogonal coordinate again, and it is displayed similarly to the Lissajous's waveform, thereby obtaining a display resolution required for adjustment.;COPYRIGHT: (C)2006,JPO&NCIPI