Patent ID: 9336981
Filing Date: 2016-05-10
CPC Classification: H01J

Claim Text:
1. A charged particle detection system, comprising: a first detector having an array of plural detection elements for detecting charged particles; a first aperture plate having a first array of plural apertures to be traversed by charged particles and disposed at a first distance from the first detector; a second aperture plate having a second array of plural apertures to be traversed by charged particles and disposed at a second distance from the first detector, the second distance being greater than the first distance; and a voltage supply configured to supply a first electric potential to the first detector, to supply a second electric potential to the first aperture plate, and to supply a third electric potential to the second aperture plate; wherein the apertures of the first aperture plate, the apertures of the second aperture plate and the detection elements of the first detector are substantially aligned relative to each other such that plural beamlets of charged particles can each traverse an aperture of the first aperture plate and an aperture of the second aperture plate to be incident on a detection element of the first detector; and wherein the first electric potential, the second electric potential and the third electric potential are selected so that charged particles of the beamlets having a kinetic energy below a threshold energy cannot traverse the first array of plural apertures of the first aperture plate and are prevented from being incident on the detection elements.