An image intensifier for the electron microscope.

An image intensifier system using a four-stage image intensifier optically coupled to a phosphor screen in the electron microscope is described. The system is shown to be limited by the quantum noise inherent in the electron image. The system can detect images down to 10 fA cm−2 which is at least an order of magnitude better than can be achieved by a fully dark adapted operator viewing the normal fluorescent screen of the microscope.