Optics: measuring and testing – By light interference – Having light beams of different frequencies
Reexamination Certificate
2006-05-16
2006-05-16
Toatley, Jr., Gregory J. (Department: 2877)
Optics: measuring and testing
By light interference
Having light beams of different frequencies
C356S500000
Reexamination Certificate
active
07046367
ABSTRACT:
The invention features a method for determining non-linear cyclic errors in a metrology system that positions a measurement object under servo-control based on an interferometrically derived position signal. The method includes: translating the measurement object under servo-control at a fixed speed; identifying frequencies of any oscillations in the position of measurement object as it is translated at the fixed speed; and determining amplitude and phase coefficients for sinusoidal components at the identified frequencies which when combined with the position signal suppress the oscillations. The invention also features a method for positioning a measurement object under servo-control based on an interferometrically derived position signal indicative of a position for the measurement object. This method includes: generating a compensated position signal based on the interferometrically derived position signal and at least one correction term that has a sinusoidal dependence on the position of the measurement object; and repositioning the measurement object based on the compensated position signal and a desired position for the measurement object.
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Connolly Patrick
Fish & Richardson P.C.
Toatley , Jr. Gregory J.
Zygo Corporation
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