An electron beam focusing device with a high power density

Abstract

The invention discloses an electron beam focusing device with a high power density. The device comprises a collecting lens module, an auxiliary collecting lens module and an objective lens module arranged in sequence along an electron beam emitting direction; the collecting lens module is used to form a first magnetic field to enable an electron beam to form a cross point; the auxiliary collectinglens module is used to form a second magnetic field such that a movement trajectory of the electron beam is parallel to the optical axis to form a parallel beam, wherein the first magnetic field is greater than the second magnetic field in terms of the magnetic field strength; and the objective lens module is used to form a third magnetic field to focus the electron beam onto a target plane. A multi-lens combination mode of the collecting lens, the auxiliary collecting lens and the objective lens realizes the intersection, parallel and focus control of the electron beam, thereby obtaining thehigh reduction ratio and small aberration of the electron beam system and the high efficiency transmission of the beam current.

Description

technical field [0001] The invention belongs to the technical field of three-dimensional nondestructive microscopic observation, and in particular relates to an electron beam focusing device. Background technique [0002] High power density electron beam focusing devices can be used in imaging devices that use electron beams to bombard targets to generate corresponding rays to scan samples. For example, Micro-Computed Tomography (Micro-CT) is a technology that utilizes The non-destructive microscopic imaging technology, which scans the sample with X-rays and inverts the scanned data into a three-dimensional image, can display the internal structure, density and defects of the tested sample at the micron level or even sub-micron level, and has been widely used. It is the development direction of micro-CT technology to improve the detection resolution and efficiency when it is applied in the fields of life science, material science and geology. The X-ray source for electron b...

AI Technical Summary

Problems solved by technology

If a multi-stage lens is simply used to reduce the small electron beam spot, its angular magnification will increase accordingly. In order to ensure the paraxial relationship in the actual lens system, the aperture of the diaphragm in the electron beam channel is generally small, and the electron beam cannot Effectively through the focusing system with large angular magnification, the electron beam current bombarding the target surface is reduced; therefore, it is difficult for the usual multi-lens focusing system to ensure that the electron beam bombarding the target surface has both large beam current and small beam current. beam spot, which in turn affects the focal spot size and power density of the generated X-rays

[0004] Most of the X-ray source focusing systems for electron beam targeting are modified or referred to the magnetic lens used in electron microscopes. When the electron beam spot on the target surface is small, the beam current is also small, and the X-ray power density generated is not high, so it is difficult to obtain high resolution. clear image

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