An
electrostatic lens is a device that assists in the transport of charged particles. For instance, it can guide
electrons emitted from a sample to an
electron analyzer, analogous to the way an
optical lens assists in the transport of light in an optical instrument. Systems of electrostatic lenses can be designed in the same way as optical lenses, so electrostatic lenses easily magnify or converge the electron trajectories. An electrostatic lens can also be used to
focus an ion beam, for example to make a
microbeam for irradiating individual
cells.