Abstract: A charged particle energy analyser has a magnetic lens such as a snorkel-type lens and a source for directing ionising radiation onto a specimen causing charged particles to be emitted from its surface. The specimen is immersed in the magnetic imaging field of the magnetic lens so that particles having energies in a predetermined energy range are brought to a focus, the energies of the focussed particles being analysed by an energy analyser. An electrode arrangement is provided for enabling the magnetic imaging field of the magnetic lens to utilise unfocussed particles to cause charge neutralisation of the specimen. Alternatively, charged particles from a source are subjected to an electric field which is transverse to the optical axis of the magnetic lens and are guided onto the specimen by the magnetic imaging field of the magnetic lens.

Abstract: A charged particle energy analyzer includes two hemispherical electrodes and means for developing an inverse square electric field in the gap between the two electrodes. An afocal charged particle lens arrangement is arranged to project a charged particle image of a sample into the electric field. Two baffles are disposed in the gap between the electrodes the baffles being effective to restrict the energy and angular divergence of the particles transmitted by the analyzer, the baffles being positioned so as to reduce the dependence of the energy and the orientation of the charged particles transmitted by the baffles on the position of the particles within the image. A two-dimensional detector is arranged to detect the charged particle image transmitted by the analyzer.