Lens Mounting

(Click on photos for larger views)

Lenses can be made from plates, as shown in these photos, or from tubes, as in your sketches. In either event, mounting and alignment are important considerations. This first view is of a short stack of lenses for very low energy electrons. The plates are mounted and aligned by 4 ceramic tubes and are spaced apart by shorter tubes. The lenses and spacers are graphite coated to reduce space charging.

The longer lens stacks shown below were aligned in the same way but the first and last lens in each stack were electrically isolated and then mechanically mounted to a tube that enclosed the whole assembly. This outer tube provided the mechanical alignment of the whole to the rest of the vacuum chamber but the individual spacers aligned and spaced the lenses with respect to each other.

Another assembly.

A closer view. (Remember to click "Back" after viewing the larger images.)

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