Development of the New Type Polarized Electron Source for SPLEEM

A new transmission type photocathode and gun for polarized electron source (PES) has been developed to enable the real‐time observation of magnetism images during thin film growth by SPLEEM. This photocathode requires for laser lights to be injected from its backside and an electron beam is extracted from its surface side. By this scheme, it is possible to make a small laser spot (⩽ 10μmφ) on the photocathode. A quantum efficiency for a strained GaAs‐GaAsP superlattice photocathode was larger than 0.1% and a brightness higher 105A⋅cm−2⋅sr−1 for an extracted current of 5μA was achieved by our PES system.