focus occurs at the sample plane. The beam is spatially focussed at the resonator, indicated in figure 2, to mitigate the effects of field imperfections.

For maximum instrument flexibility, parallel and convergent beams of varying diameter are needed at the sample which is impossible to achieve with a standard magnetic lens. Condenser-Objective (CO) lenses, established in TEM for four decades, see a converging beam passing through two (upper and lower) strong lenses acting to collimate the beam at a radius 2$\sigma$(r) on the micron scale. Changing the C3 lens strength allows non-parallel illumination such that spot size and convergence angle are independent.

Post-sample optics consist of intermediate and projector lenses, providing magnification and delivering the beam with appropriate dimensions to the electron detector. As temporal information is encoded by a pump-probe measurement, following delivery of a short electron pulse to the sample, the evolution of the electron image as a function of delay requires only that the post-sample optics preserve the image, not the temporal characteristics. Furthermore, the action of the compressor will cause a strong temporal divergence, hence the charge density drops. This results in the post-sample electron transport optics acting in a manner akin to a TEM.

Propagating 