High Voltage Metrology with Collinear Laser Spectroscopy

We present results of laser spectroscopic high voltage measurements on the 5 ppm relative uncertainty level using a pump and probe scheme on Ca+ ions. With the two-stage laser interaction and with a reference measurement we can eliminate systematic effects like differences in contact potentials of electrode materials, thermo-electric voltages, and the unknown starting potential of the ions in the ion source. Our measurements are compatible with the 5 ppm precision limits of the high voltage dividers used for comparison and demonstrate an unprecedented increase in the accuracy of laser-based high voltage measurements by a factor of 20.