Multi-beam electron characterization tool with telecentric illumination

A multi-beam electron source is disclosed. The multi-beam source includes an electron source, a grid lens assembly, and a multi-lens array assembly. The multi-lens array assembly includes a set of lenses disposed across a substrate. The grid lens assembly is configured to cause a primary electron beam from the electron beam source to land on the multi-lens array assembly telecentrically. The multi-lens array assembly is configured to split the electron beam from the electron beam source into a plurality of primary electron beams. The grid lens assembly includes a first lens element and a second lens element, wherein the first lens element and the second lens element are separated by a gap of a selected distance. The grid lens assembly further includes a grid element including a set of apertures, wherein the grid element is disposed within the gap between the first lens element and the second lens element.