Abstract
High voltage measurement based on electro-optical effect of ADP crystal plate is described. Though ADP crystal is uniaxial, when voltage is applied across the crystal, the indey ellipsoid in the crystal is rotated and the lengths of the axes change. For a field Ez in z direction across the Z-cut crystal plate, the axes of the ellipsoid are rotated by -45° in xy plane independent of Ez, and the birefringence along z-axis is proportional to Ez. Then the retardation of lights in z direction becomes proportional to applied voltage across the crystal plate. Using Senarmont compensator method, the retardation is measured by rotation of the analyzer. Proportionality of this angle of rotation to the applied voltage makes the measurement of the latter possible. Accuracy of measurement is about ±50 V over any range. Measured value of electro-optical coefficient γ63 of ADP crystal is 8.48×10-7cm/kV.
