Method of operating an electron beam measuring device

摘要

In modern electron beam measuring devices the thermal La/B6 or field emission source is replaced by a photocathode acted upon by a pulsed laser beam. Since the width of photoelectron pulses corresponds approximately to the width of the laser pulses, theses devices are particularly suitable for stroboscopic measurements in fast gallium arsenide circuits. The expenditure on apparatus for generating the photoelectron pulses is considerable since means for doubling the frequency of the primary laser light are necessary. It is therefore proposed to irradiate the cathode of the electron beam measuring device with photons of energy EPh<W (W:=electron work function of the cathode material) and to reduce the work function with the aid of an external electrical field to such an extent that photoemission occurs, but not field emission.