Patent ID: 7531812

Claim:
An electron detection system for a scanning electron microscope providing a primary electron beam and defining a beam axis, said electron detection system comprising: a head body having an upper portion and a lower portion; a lower throttling aperture disposed at said lower portion of said head body said lower throttling aperture separating spaces of different gas pressures and having a hole defining a passage for said primary electron beam; a microporous plate having a hole and being arranged in said head body: said microporous plate separating spaces of different gas pressure and said microporous plate having a first side directed to said lower throttling aperture and a second side opposite said first side; a screen pipe arranged in said hole of said microporous plate; a seal for fixing and sealing said screen pipe in said hole of said microporous elate; said hole of said lower throttling aperture and said screen pipe being arranged along a straight axis; at least a first scintillator arranged on said second side of said microporous plate connected with a first light pipe and a first photomultiplier; and, at least a second scintillator arranged on said second side of said microporous plate connected with a second light pipe and a second photomultiplier.