Einzel Lens Hardware
Before we had conceived of the idea of making the focusing lens a two-electrode system, rather than a three-electrode Einzel lens, we planned to machine three pieces of copper, two MACOR washers to insulate them from each other, and a larger MACOR insulating housing to go around them all, as can be seen from the following images:
We ended up scrapping this design once we discovered that a two-lens system would more thoroughly meet our requirements, since it focused the electron beam much better and only required one plate to be grounded and the other to be held at some potential. The basic elements of the lens stayed the same - machining the lens and its housing out of copper and MACOR - but we were able to make the housing one whole piece and change the feedthrough method.
A CAD model of the entire MXS assembly (including our lens) follows:
Since our lens required very precise machining, we asked Bruce in the Olin machine shop to make these pieces for us, which he managed to do in one day (Thanks Bruce!) and we shipped it to Goddard the next day. Here are some pictures of our lens for your enjoyment!