A charged particle (e.g. photoelectron) spectrometer is operable in a first mode to produce an energy spectrum relating to the composition of a sample being analysed, and in a second mode to produce a charged particle image of the surface of the sample being analysed. A detector is used to detect charged particles produced in both modes of operation. A method of operation of the spectrometer includes the step of selecting which of said first and second modes to use and the detector being operated accordingly.