| 摘要 |
<P>PROBLEM TO BE SOLVED: To inexpensively provide a measuring apparatus for highly accurately measuring a position of a measuring object. <P>SOLUTION: An apparatus for acquiring a digital reference signal from reference light modulated by a first frequency by a modulation part, acquiring a digital measurement signal from measurement light reflected from a measuring object irradiated with light modulated by the first frequency and processing the digital reference signal and the digital measurement signal to measure the position of the measuring object includes: first and second synchronizing detection parts for multiplying the digital measurement signal by a sine signal or a cosine signal synchronizing with the digital reference signal and respectively outputting a signal having the second frequency and a harmonic component; first and second decimation filters for filtering the signal outputted from the first or second synchronizing detection part by a decimation frequency to attenuate the harmonic component; and an operation part for calculating the position of the measuring object based on signals outputted from the first and second decimation filters. <P>COPYRIGHT: (C)2012,JPO&INPIT |
