when the primary beam consists of accelerated electrons, the probe is termed an electron microprobe, when the primary beam consists of accelerated ions, the term ion microprobe is used. the term microprobe may also be applied to optical analytical techniques, when the instrument is set up to analyse micro samples or micro areas of larger specimens. such techniques include micro raman spectroscopy, micro infrared spectroscopy and micro libs. all of these techniques involve modified optical microscopes to locate the area to be analysed, direct the probe beam and collect the analytical signal.