Ray-Tracing Electrons through a Magnetic Lens

Abstract

The primary way to understand the trajectory of electrons through a Transmission Electron Microscope (TEM) is through numerical ray-tracing. While free resources are available for optical ray-tracing, to the best of the authors' knowledge, no free and open source package exists which enables ray-tracing for electrons through the electromagnetic lenses of a TEM system.

TEMGYM Advanced – NanoMi lens characterisation

“…Furthermore, this work did not apply the parallelised ray-tracing capabilities of TEMGYM Advanced to the NanoMi Lens (see Landers et al 8 ). In future work, with full access to the 3D CAD model of the entire NanoMi microscope, TEMGYM Advanced can implement a complete digital twin and apply the parallelised ray tracing code to the entire instrument, provided 3D FEM methods can be used to obtain the field of the stigmator and dipole deflectors inside the microscope also.…”

“…The aberrations of the lens create a deformed spot whose shape depends on the aberration coefficients. only selecting specific terms in the aberration polynomial generated by the DA method, one can inspect how each individual aberration impacts the overall beam shape (see 8,46 ). Out of all the aberration terms, spherical aberration is the most important as it is the only aberration that does not vanish when the object is placed on the optical axis; it is dependent only on the cube of the initial beam angle.…”