Calibrated electro-optic E-field sensors for hyperthermia applications

E-field measurements are an important task for the investigation of newly d eveloped hyperthermia applicators as well as for online control of hyperthe rmia treatments. Compact and non-perturbing integrated optical E-field sens ors based on LiNbO3 as well as optical E-field sensors based on infrared em itting diodes and light bulbs are suitable for nearfield measurements of hy perthermia antennas. In order to investigate their properties a calibration cell with transverse electromagnetic (TEM) waves has been constructed. By using this cell, calibration curves and directional patterns for all sensor s have been measured. Due to the threshold behaviour of the IRED and light bulb sensor, only the LiNbO3 sensor is capable of measuring weak fields ins ide an applicator or a homogeneous phantom.