A versatile opto-electronic probe for high-voltage pulsed applications

This paper describes a novel high-bandwidth high-voltage measurement probe, suitable for use in a wide range of pulsed-power applications where more conventional probes are unsuitable. A high quality capacitive voltage divider feeds a Pockels cell, which has negligible effect on the bandwidth of the divider system. Light from a laser diode is fed to the cell via a long optical fibre, with the output signal being modulated by the divider output voltage before it is recorded on a digital storage oscilloscope. The use of a finite-element package in the design of the probe geometry leads to a compact and convenient shape, in which stray capacitance is minimised. Experimental results show clearly that the 3 ns rise time of the probe in response to a 45 kV pulse is significantly less than that of a high-quality electromagnetic probe