Electron optical systems and charged particle beam devices

Abstract

This invention discloses an electron optics system and a charged particle beam device. The system includes: a first lens for adjusting the numerical aperture of the main electron beam reaching the sample, whereby the main electron beam generates a signal electron beam; an adjustable lens assembly located between the first lens and the objective lens for focusing or expanding the signal electron beam to adjust its transmission path; and a detector assembly located above the adjustable lens assembly for acquiring the signal electron beam. The electron optics system has an optical axis, with the first lens, adjustable lens assembly, and detector assembly all coaxially aligned with it. Its advantages are: the system controls the signal electron beam current through the adjustable lens assembly, eliminating the need for additional structures such as Wien filters, and preventing induced dispersion of the main electron beam on the sample.

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