3.1. Overview of Electron Column

There have been great technical advances in microprobes during the last 30 years (mostly in automation and electronics), but all microprobes are built around an electron column, which produces a stable electron beam, controls beam current, beam size and beam shape, and rasters the beam for SEM work. Electron optics are a very close analog to light optics, and most of the principles of an electron beam column can be understood by thinking of the electrons as rays of light and the electron optical components as simply their optical counterparts.

The schematic diagram below (Figure 3.1) shows the entire electron column of the Cameca MBX microprobe and the associated wavelength-dispersive spectrometers (WDS). The following sections will examine this components in detail.

MBX electron column

Figure 3.1. The basic layout of the Cameca MBX electron microprobe. (1) Electron gun with mechanical alignment. (2) Adjustable anode to Wehnelt distance. (3) Condenser lens in electron column with beam current regulator. (4) WDS spectrometer. (5) Minicoil probe-forming objective lens. (6) Specimen chamber with mechanical stage. (7) Coaxial light optical system. (8) Scanning coils. (9) Sample airlock. (10) Vacuum system.


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Copyright 1997-2003, James H. Wittke

Last update: 01/18/2006 01:47 PM.