Optically addressed, thermionic electron beam device

An electron microscope comprising:

• an electron source comprising:
• a vessel forming a chamber;
• a cathode disposed within the chamber, the cathode comprising a low dimensional electrically conductive material having an anisotropic restricted thermal conductivity;
• an electrode disposed in the chamber, the electrode being connectable to a power source for applying a positive voltage to the electrode relative to the cathode for accelerating free electrons away from the cathode to form an electron beam when the cathode is illuminated by electromagnetic (EM) radiation such that the cathode thermionically emits free electrons;
• an electron emission window in the vessel for passing a generated electron beam out of the chamber;
• a sample stage for holding a sample, the sample stage located proximate to the electron emission window such that the generated electron beam from the electron beam source irradiates the sample stage, the sample stage comprising:
• an electron detector to detect secondary and backscattered electrons from a sample held in the sample stage that is being irradiated with an electron beam generated by the electron beam source
• a focusing element located between the electrode of the electron beam source and the sample stage for focusing an electron beam generated by the electron beam source on a sample on the sample stage;
• a scanning mechanism for performing one of mechanically moving the sample, and deflecting the electron beam incident on the sample stage, such that the electron beam is scanned over a sample held in the sample stage.