Magnetically filtered low loss scanning electron microscopy

An electron microscope which includes a detector (18) which is located in the magnetic field used to focus the primary electron beam onto the sample (10). The focussing magnetic field is used to energy-filter and/or energy analyze the scattered electrons without the need for additional equipment, such as a retarding-field energy filter. The magnetic field of the condenser-objective lens (or of any other type of magnetic lens) of the microscope provides the filtering and/or analyzing action, and the detector (18) can be located so as to collect only low-loss electrons.