| 摘要 |
PROBLEM TO BE SOLVED: To reduce uncertainty in calibration below the wavelength cycle of a displacement calibrating system by correcting an error in a position detection signal and reducing an error in position, thereby reducing the calibration time and improving the accuracy in reference position. SOLUTION: Two-phase sine wave-like displacement detection signalsϕA<SB>n</SB>,ϕB<SB>n</SB>(n=1, 2, 3,...) having different phases, and a position detection signal X<SB>n</SB>(n=1, 2, 3,...) of an object for correction 8 are subjected to sampling at the same time for displacement calibration. For each sampled displacement detection signalϕA<SB>n</SB>andϕB<SB>n</SB>, based on position detection signalsϕA<SB>n-k1</SB>-ϕA<SB>n+k2</SB>andϕB<SB>n-k1</SB>-ϕB<SB>n+k2</SB>in a range more than 1 wavelength includingϕA<SB>n</SB>andϕB<SB>n</SB>, errors in amplitude, offset and phase of the position detection signalsϕA<SB>n</SB>andϕB<SB>n</SB>are corrected to obtain:ϕA<SB>n</SB>'=A<SB>n</SB>'cos(θ<SB>n</SB>+ΔθA<SB>n</SB>')+VA<SB>n</SB>'; andϕBn'=B<SB>n</SB>'sin(θ<SB>n</SB>+ΔθB<SB>n</SB>')+VB<SB>n</SB>' (A<SB>n</SB>'=B<SB>n</SB>',ΔθA<SB>n</SB>'=ΔθB<SB>n</SB>', VA<SB>n</SB>'=VB<SB>n</SB>'). A reference position detection signal Pn' in which an error in wavelength cycle and a displacement detection detection signal for 1/2 cycle is reduced is used to calibrate the displacement detection signal Xn as an object for calibration. COPYRIGHT: (C)2003,JPO
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