Patent ID: 7640142
Filing Date: 2009-12-29
Classification: B82Y,G03F,H01J

Abstract:
1. A position measurement apparatus comprising: a movable stage structure; a measurement unit using a laser to measure a moved position of the stage and to output a corresponding measured value; a first filter configured to attenuate a first component of a certain frequency region of the measured value outputted by said measurement unit; a second filter connected in parallel with said first filter configured to attenuate a second component other than the certain frequency region of the measured value outputted by said measurement unit; a third filter connected in series to said second filter with the series connection of said second and third filters connected in parallel with the first filter, configured to attenuate the first component of said certain frequency region of the measured value outputted by said measurement unit; and a processing unit configured to combine an output of said first filter and an output of the series connection of the second and third filters and to thereby output a first combined value, wherein transfer function of the first filter is given by 1/(1+τ