| 摘要 |
<P>PROBLEM TO BE SOLVED: To measure residual DC within accurate and in a short period of measuring time, by calculating an offset voltage in the case that transmittance corresponding to the maximum amplitude of an amplitude voltage and transmittance corresponding to the minimum amplitude thereof are equal to each other. Ž<P>SOLUTION: A residual DC measuring device 30 is equipped with: a signal acquiring section 31 which acquires a plurality of data of sets of transmittance at positive polarity time, being maximum transmittance when a rectangular voltage gets positive for each offset voltage, and the offset voltage at that time, and acquires a plurality of data of sets of transmittance at negative polarity time, being minimum transmittance when a rectangular voltage gets negative for each offset voltage, and the offset voltage at that time; and a linear approximation/intersection calculating section 33 which acquires an approximate straight line from a plurality of data sets of the transmittance at positive polarity time and the offset voltage acquired by the signal acquiring section 31, acquires an approximate straight line from a plurality of data sets of the transmittance at negative polarity time and the offset voltage, and acquires an offset voltage corresponding to an intersection of the two approximate straight lines. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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