Figure 3
From: A new approach for fast field calculation in electrostatic electron lens design and optimization
The illustration of the lens system depicts voltages at the outer radius of the lens, with the voltages before the first electrode and after the last electrode set to the voltage of the first electrode and the last electrode, respectively. In (a), there are holes in both the first and the last electrodes. In (b), there is a hole in the first electrode, while the last electrode is closed.
