Abstract
The simultaneous detection method for both an electric field and a small quantity of decomposition products is proposed by using a sensor head which consists of a twisted nematic (TN) liquid crystal (LC) cell sandwiched between a pair of cholesteric LC cells and a corner cube prism coated with dye films. The electric field can be detected as changes of optical retardations induced in the TN LC cell at the wavelength of a selective reflection band of the cholesteric LC. The ppm concentration of the decomposition products generated from an electric discharge in SF6 can also be optically detected as spectrum changes of dye films deposited on the prism at the other wavelength outside the selective reflection band. The optical sensing system using the several sensor heads and an OTDR (Optical Time Domain Reflectometry) method can be applied to monitor and detect simultaneously the electric field and the decomposition products at two different wavelengths. In addition, their locations can also be determined.
