Research on a New Optical Method for Space Charge Measurement of Insulating Materials

To achieve the measurement of space charge inside insulating materials under high-frequency voltage conditions, an optical method based on stress birefringence effect is proposed. The method is expected to achieve high spatial and temporal resolutions due to its high signal-to-noise ratio, picosecond-scale excitation, and continuous wave detection by using Terahertz wave and ellipsometry measurement method. An ellipsometry system is then built to verify the key part of the proposed method. It is found that the measured signal from the balanced detector can accurately show the displacement process of actuator with different amplitudes and frequencies. The explorative research in this paper will be an important basis for the further development of the proposed optical method.