An electron detector assembly configured for detecting electrons emitted from a sample irradiated by an electron beam, comprising a scintillator including a scintillator layer, the scintillator layer emitting light signals corresponding to impingement of electrons thereupon, a light guide plate coupled to the scintillator layer and comprising a peripheral surface, and a single or plurality of silicon photomultiplier devices positioned upon the peripheral surface and arranged perpendicularly or obliquely relative to the scintillating surface, the silicon photomultiplier device being configured to yield an electrical signal from an electron impinging upon the scintillator layer.