[en] This review paper summarises results of ion optics development work conducted on the Melbourne Proton Microprobe and the associated Pelletron accelerator. The properties of a field ionization ion source have been investigated with the aim of replacing the existing R.F. ion source in the accelerator in order to obtain a brighter beam for the microprobe. The electrostatic emitter lens in the terminal of the accelerator has also been investigated with the aim of improving the focus of the accelerated beam. Finally, the aberrations of the probe forming lens system have been studied and it is shown how some of these may be corrected with an octupole lens