Patent ID: 7714285

Claim:
A spectrometer for surface analysis of a sample by irradiation of the sample surface by primary particles, the spectrometer comprising: a collection chamber for receiving secondary charged particles and image light from the sample surface, the collection chamber having a first axis in use substantially normal to the sample surface, the collection chamber comprising: a secondary charged particle lens arrangement arranged to focus at least a proportion of the emitted secondary charged particles in a downstream direction along the first axis and thereby to define a charged particle optical crossover location; and a light-reflecting optical element positioned downstream of the secondary charged particle lens arrangement and having a second axis in use substantially normal to the sample surface, the optical element being arranged to receive image light from the sample surface and to reflect that light away from the second axis for providing a viewable image of the sample surface, wherein the optical element is positioned at, or near to, the charged particle optical crossover location and the optical element comprises an opening therethrough, such that at least a proportion of the focused secondary charged particles may pass through the opening for undergoing spectroscopic analysis downstream thereof substantially without obstruction by the optical element.