Abstract
A new scanning electron microscope has been built which uses a lanthanum hexaboride cathode electron gun. The microscope has three magnetic lenses which are prealigned in the electron optical column to better than 20 micron. The final lens has a design spherical aberration of 1.8 cm for a 6 mm working distance. The pole-pieces of the final lens have been machined round within 0.25 micron and are aligned with respect to the axis of the lens to better than 10 micron. The electron gun which has been described previously uses a lanthanum hexaboride rod cathode. The cathode has approximately two orders of magnitude longer life than a 5 mil tungsten hairpin and is capable of producing an electron beam with a maximum brightness of 5.6 x 105 A/cm2 /ster at 12 KV. This brightness is approximately five times greater than that produced by a 5 mil tungsten hairpin under similar conditions.
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Schedule a callMore From: Proceedings, annual meeting, Electron Microscopy Society of America
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