Scanning electron microscopes have traditionally been used for observation and microanalysis of samples. Positioning and testing of samples has usually been performed out of the SEM chamber e.g. electrical test benches, sample preparation. However, due to miniaturization in semiconductor technology, optics, micro-mechanics, medicine, gene- and biotechnology, highly precise positioning techniques are becoming increasingly important. This may be performed using an optical microscope, or more commonly, within the SEM chamber itself.