Patent ID: 7301263

Claim:
A multiple electron beam source comprising: (a) a photocathode comprising a photon receiving surface to receive a photon beam and an electron emitting surface to emit electrons; and (b) an array of electron transmission gates having a surface facing the electron emitting surface of the photocathode, the surface of the array of electron transmission gates spaced apart from the electron emitting surface of the photocathode by a separation distance d g , each electron transmission gate comprising: (i) a membrane having opposing first and second surfaces; (ii) an anode on the first surface of the membrane; (iii) an insulator on the second surface of the membrane; (iv) an aperture through the anode, insulator and membrane; and (v) a gate electrode on the insulator, the gate electrode positioned about the aperture, the gate electrode capable of receiving a gate control voltage that controls the transmission of electrons emitted from the photocathode through that electron transmission gate.