| 摘要 |
PROBLEM TO BE SOLVED: To allow the measurement of a surface potential in a high voltage, and to downsize an instrument as the whole. SOLUTION: This instrument is provided with the first optical waveguide 60 of which the one portion is wired to a movable part of a substrate 56 having a probe 18, and the second optical waveguide 61 having an end face opposed to an end face of the first optical waveguide 60 and wired to a fixing part of the substrate 56, and a voltage impressing circuit 63 for impressing a voltage to the probe, and a movement detecting circuit 64 for detecting movement of the probe 18 based on light passing through the first and second optical waveguides 60, 61 are provided to be separated electrically in the instrument. The movement detecting circuit 64 for detecting the movement of the probe 18 is precluded from disturbed by the voltage impressed to the probe 18, and the surface potential of the high voltage is allowed to be measured. The instrument is compactified as the whole, since the detecting circuit 64 is provided on the substrate 56 the same as the substrate 56 where the probe 18 is formed.
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