  Low voltage scanning electron microscopy is a powerful tool for examining
surface features and imaging beam sensitive materials. Improving resolution
during low voltage imaging is then an important area of development. Decreasing
the effect of chromatic aberration is one solution to improving the resolution
and can be achieved by reducing the energy spread of the electron source. Our
approach involves retrofitting a light source onto a thermionic Lanthanum
Hexaboride (LaB6) electron gun as a cost-effective low energy spread
photoelectron emitter. The energy spread of the emitter's photoelectrons is
predicted to be between 0.11-0.38eV depending on the photon energy of the UV
light source. Proof of principle images have been recorded using this
retrofitted photoelectron gun and an analysis of its performance is presented.
