Patent ID: 7470915

Claim:
A detector system for secondary and backscattered electrons in a scanning electron microscope having a specimen stage, the detector system comprising: an upper scintillator and a lower scintillator disposed in spaced relationship to each other; a focusing electrode and a microporous plate disposed between said upper and lower scintillators; said lower scintillator being mounted so as to face toward said specimen stage; a photomultiplier; a first light guide connecting said lower scintillator to said photomultiplier and a second light guide connecting said upper scintillator to said photomultiplier; said photomultiplier having an end face; and, said first and second light guides having respective end faces facing toward said end face of said photomultiplier; and, a movable diaphragm having an aperture; said movable diaphragm further having a first side and a second side facing away from said first side; and, said movable diaphragm being mounted between said respective end faces and said end face of said photomuitiplier so as to cause said first side of said movable diaphragm to face toward said respective end faces and said second side of said movable diaphragm to face toward said end face of said photomultiplier.