| 摘要 |
<p>PURPOSE:To measure the absolute potential at a predetermined part of an object to be measured by detecting the polarizing state of the laser beam emitted from an electrooptical material by a light detection means. CONSTITUTION:The laser beam I0 from a low noise pulse light source 60 transmits through a transparent auxiliary electrode 56 along the axis A-A of an optical probe 48 to be incident to an electrooptical material 50. The polarizing state of the laser beam I0 changes according to a refractive index change in the material 50, that is, the beam I0 is modulated to be emitted from the material 50 as laser beam R0. The emitted beam R0 transmits through the electrode 56 and the change of the polarizing state thereof, that is, the modulation result thereof is detected by a light detection means 62. Subsequently, the voltage VS from a voltage applying apparatus 58 is gradually increased and, when the change of the polarizing state of the laser beam R0 can not be detected by the means 62, it means that the voltage VS becomes same to the voltage V0 of the electrode 56 and, therefore, by detecting the voltage VS at this time by a voltmeter 58B, the absolute voltage V0 of the electrode 56 can be measured.</p> |
