Optical Effects of Fringing Fields in Kerr Cells

Fringing fields can lead to pronounced optical effects when a Kerr cell containing a dielectric liquid is observed between crossed polarizers. Such effects must be considered when using Kerr cells for accurate measurement of either Kerr coefficients or pulsed high voltages. Calculations of both the fringing fields and their resultant optical effects are made assuming a Rogowski contour for the electrodes. The results agree well with experimental observation. Corrections are obtained for the effective length l' of the electrodes for arbitrary positioning of a light ray parallel to the electrode edges. The literature value of l' = l(1 + t/lπ) is recovered for a ray centered between the electrodes, where I is the electrode length and t the electrode separation. These results are shown to hold when the electrode length and width (w) obey I > w ⩾ 2t and when the container walls of the cell are more than 2t from the electrode ends and sides.