= Solution
The electron-optical column contains an <electron gun>, an accelerating supply, a <condenser lens> system, an objective aperture, an <electron objective lens>, scan coils and alignment/stigmation controls. The <electron gun> may use <thermionic emission> or <field emission>. The <condenser lens> system sets the incident probe current and source demagnification; the <electron objective lens> focuses the probe on the specimen. A movable specimen stage controls position, tilt and working distance. The column and specimen chamber need a <vacuum> system, appropriate pumps and specimen-transfer hardware. Detectors collect <secondary electrons>, <backscattered electrons> or characteristic <X-rays>; amplification and synchronized raster acquisition assign a measured signal to each image pixel. The first two signals provide different imaging information, while characteristic <X-rays> allow elemental analysis. \b[A source, probe-forming optics, raster scan, specimen stage, detectors, acquisition electronics and <vacuum> system form the essential chain.]<Scanning Electron Microscope A To Z by JEOL>[printed pp.3–6, construction of the column, detectors and vacuum system]{ref}
Back to article page
